Ex. No.1 Date: DISEASES OF RICE AND WHEAT RICE 1. Blast Signs and symptoms initial symptoms are white to gray-green lesions or spots with darker borders produced on all parts of shoot older lesions elliptical or spindle-shaped and whitish to gray with necrotic borders lesions wide in the center and pointed towards end lesions may enlarge and coalesce to kill the entire leaves symptoms also observed on leaf collar, culm, culm nodes, and panicle neck node nodal infection causes the culm to break at the infected node few, no seeds, or whiteheads when neck is infected or rotten a. Leaf blast: On the leaves, the spots are typically spindle shaped with dark brown margin and grey centre. Several spots coalesce resulting in bigger lesions and leading to drying of affected leaves. b. Nodal blast: Necrotic black lesions are observed at nodes resulting in weakening of nodal region. The portions above the node dries up and break at the point of infection. c. Neck blast: The neck region of affected panicle becomes black and necrotic and the transport of nutrients to grains is blocked leading to chaffiness or ill filling of grains. The ear head breaks at the neck region. d. Grain infection: The branches of the panicle and the grains are also infected. Dark brown spots appear on the glumes. Fungus : Pyricularia oryzae (Sexual stage: Magnoporthe grisea). The mycelium is hyaline when young and olivaceous when it matures, septate, interand intracellular. Conidiophores emerge through stomatal opening or pierce through the epidermal cells. Conidiophores are olivaceous, septate and geniculate. Conidia are pyriform (pear shaped), hyaline to pale olive, and two septate (three celled) and are provided with a basal appendage called hilum. Why and where it occurs: In the tropics, blast spores are present in the air throughout the year, thus favoring continuous development of the disease. The infection brought about by the fungus damages upland rice severely than the irrigated rice. It rarely attacks the leaf sheaths. Primary infection starts where seed is sown densely in seedling boxes for mechanical transplanting. In the temperate countries, it over seasons in infested crop residue or in seed. Cloudy skies, frequent rain, and drizzles favor the development and severity of rice blast. High nitrogen levels, high relative humidity, and wet leaves encourage infection caused by the fungus. The rate of sporulation is highest with increasing relative humidity of 90% or higher. For leaf wetness, the optimum temperature for germination of the pathogen is 25-28 °C. Growing rice in aerobic soil in wetlands where drought stress is prevalent also favors infection. Economic importance Rice blast is one of the most destructive diseases of rice because of its wide distribution and its destructiveness. In India, more than 266,000 tons of rice were lost, which was about 0.8% of their total yield. In Japan, the disease can infect about 865,000 hectares of rice fields. In the Philippines, many thousand hectares of rice fields suffer more than 50% yield losses. A 10% neck rot causes yield loss of 6% and 5% increases in chalky kernels. When damage is important Rice blast infects the rice plant at any growth stage. Rice seedlings or plants at the tillering stage are often completely killed. Likewise, heavy infections on the panicles usually cause a loss in rice yields Factors favouring disease development presence of the blast spores in the air throughout the year upland rice environment cloudy skies, frequent rain, and drizzles high nitrogen levels high relative humidity and wet leaves growing rice in aerobic soil in wetlands where drought stress is prevalent Blast life cycle 2. Brown Spot / Sesame Leaf Spot Symptoms seedlings have small, circular or oval, brown lesions, which may girdle the coleoptile and cause distortion of the primary and secondary leaves (symptom is called seedling blight) Infected seedlings become stunted or die Young or underdeveloped lesions on older leaves are small and circular, dark brown or purplish brown A fully developed lesion on older leaves is oval, brown with gray or whitish center with reddish brown margin Lesions on older leaves of moderately susceptible cultivars are tiny and dark When infection is severe, the lesions may coalesce, killing large areas of affected leaves. Infected glumes with black or dark brown spots Velvety appearance of lesions on infected glumes under severe conditions Infected grains with black discoloration or with brown lesions Infected young roots with black discoloration Fungus: Helminthosporium oryzae (Syn: Bipolaris oryzae, Drechslera oryzae). The mycelium is dark brown, septate and both inter-and intracellular. Conidiophores emerge through the stomatal opening or pierce through epidermal cells. The conidia are brown, multiseptate, straight or slightly curved, tapering at both ends and eight to ten septate. Why and where it occurs The fungus can survive in the seed for more than 4 years. Infected seeds, volunteer rice, infected rice debris, and several weeds are the major sources of inoculums in the field. Infected seeds give rise to infected seedlings. The fungus can spread from plant to plant and in the field by airborne spores. The disease is common in nutrient-deficient soils and unflooded soil but rare on rice grown on fertile soils. Abnormal soils, which are deficient in nutrient elements, or soils in a much-reduced condition in which toxic substances accumulate favor the development of the disease. There is no loss in yield in light infection. Epidemics in India have resulted in 14-41% losses in high yielding varieties. Young panicles remain within the sheath or may emerge partially. causing the formation of either unfilled grains or spotted or discolored seeds giving rise to infected seedlings. The disease was considered to be the major factor contributing to the “Great Bengal Famine” in 1942 resulting to yield losses of 50% to 90% and caused the death of 2 million people. Yield losses due to brown spot epidemic in Bengal in 1942 was attributed to continuous temperature of 20-30°C for two months. rice debris. Sometimes the spots may be with brown margin and grey centre. and can cause 10-58% seedling mortality. thus killing the whole leaf. It also affects the quality and the number of grains per panicle and reduces the kernel weight. When damage is important It is observed during the maximum tillering up to the ripening stages of the crop.Disease development is favored by high relative humidity (86-100%) and optimum temperature between 16 and 36°C. White powdery growth of the mycelium is seen inside the leaf sheath and young panicle rots. and several weeds poorly drained or nutrient deficient soils abnormal soils. Sheath Rot Symptoms: The disease appears at the boot leaf stage.5 cm long. which are grown from heavily infected seeds. and higher-than-normal temperature and rainfall at the time of flowering and grain-filling stages. Economic importance The disease causes blight on seedlings. Factors favouring disease development presence of infected seeds. The spots may enlarge and coalesce and cover most of the leaf sheath. which are deficient in nutrient elements temperature ranging from 25-30oC water stress and high humidity maximum tillering up to the ripening stages of the crop Life cycle 3.5 to 1. Damage is important when infection occurs in the seed. Leaf sheath enclosing the earhead exhibits greyish brown oblong to irregular patches of 0. unusually cloudy weather. . Numerous spots or big spots on a leaf may result in blight. The reduction in yield can be as high as 45% in severe infection and 12% in moderate infection. The glumes are discoloured. Leaves must be wet for 8-24 hours for infection to occur. volunteer rice. Sclerotia are more or less globose but flattened below. Sclerotia and mycelia may be produced on the lesions. The disease usually infects the plant at late tillering or early internode elongation growth stages. hemispherical. which are initially watersoaked to greenish gray and later becomes grayish white with brown margin. nitrogenresponsive improved varieties favor the development of the disease. 4. It usually starts at the base of the plant near the water level. greenish-gray and water-soaked and usually develop near the water line in lowland fields Older lesions are elliptical or ovoid with a grayish white center and light brown to dark brown margin Lesions may reach the uppermost leaf under favorable conditions Lesions may coalesce forming bigger lesions with irregular outline and may cause the death of the whole leaf Severely infected plants produced poorly filled or empty grains. the symptoms are observed on the upper leaf sheath and on the leaf blade. ellipsoidal or ovoid. flattened at the bottom. It is commonly assumed that the critical factors for disease development are relative humidity and temperature.Fungus: Sarocladium oryzae (Syn: Acrocylindrium oryzae). St: Thanatephorus cucumeris). white when young. unicellular. Conidia are small. High supply of nitrogen fertilizer. and growing of high-yielding. which are irregular. Later. High leaf wetness and high frequency of tissue contacts among plants also favor the disease. The pathogen can be spread through irrigation water and by movement of soil and infected crop residues during land preparation. Sclerotia are compact masses of mycelia. They are white when young and turn brown or dark brown when old. especially those on the lower portion of the panicles Fungus: Rhizoctonia solani (Sex. The mycelium is colourless and septate. Confirmation The disease is easily distinguished by the irregular lesions. high-tillering. and turn brown or dark brown when mature . Conidiophores are branched once or twice. The mycelium is colourless in the early stage but becomes yellowish brown when old. each time with 34 branches in a whorl. The disease can be confirmed by the presence of sclerotia. Disease may spread from one hill to another through leaf-to-leaf or leaf-to-sheath contacts. Why and where it occurs The disease is soilborne. These lesions are usually found on the leaf sheaths near the waterline and on the leaves. hyaline and cylindrical. Relative humidity ranging from 96 to 100% and temperature ranging from 28-32°C have been reported to favor the disease. Sheath Blight Symptoms lesions are small. When the culm is split open longitudinally. Fungus: Fusarium moniliforme. mostly one celled. narrow at both ends with 3-5 cells. St: Gibberella fujikuroi) the mycelium is yellow to rosy white and inter-and intracellular. Rice sheath blight is an increasing concern for rice production especially in intensified production systems. Adventitious roots are also produced from the first two or three nodes above the ground level. Economic importance Sheath blight is considered to be an important disease next to rice blast. Mustard-like black sclerotia are produced from the mycelium. a yield loss of 50% was reported when susceptible cultivars were planted. Fungus: Sclerotium oryzae. Production of green tillers from the base of the affected plants can be seen. Under favorable conditions. Foot Rot Symptoms: The pathogen attacks both in the nursery and transplanted crop.When damage is important The disease starts during the maximum growth stage of the rice crop. the affected tillers are taller than the normal plants with longer internodes and come to flowering earlier than the healthy plants. mainly concentrated in the xylem vessels. (Sex. When an infected culm is split open. the disease caused a yield loss of as high as 20% and affected about 120. In the main field. Studies at IRRI showed that sheath blight causes a yield loss of 6% in tropical Asia. The sclerotia are found in the stelar region at the culm. The mycelium is light brown and septate. 7. the disease increases as the plant grows older. Stem Rot Symptoms: Infection takes place at the base of the plant and rotting takes place at the culm region. 5. In Japan. numerous sclerotia are seen in the inner side. sometimes two celled and are oval or fusiform. In the United States. Affected plants remain stunted and very rarely produce earheads. lean and lanky. Macroconidia are sickle shaped. 6.000 hectares. The microconidia are hyaline. The affected seedlings in the nursery are chlorotic. The damage caused by the disease depends on the infection of the plants at plant growth stages.000-190. a whitish cottony mycelium can be seen. A yield loss of 25% was reported if the flag leaves are infected. False Smut . begin to fold and roll completely along the mid-rib. turn yellow or grey ultimately the tillers in the hill will die. The immature spores are orange in colour and turn brownish green at maturity. Bacterial Leaf Blight (BLB) Symptoms: i. Leaf blight: Symptoms are mainly confined to leaves. Initial infection appears as dull greenish water-soaked or yellow spots on the leaves. The pathogen forms a stroma over the entire length and girth of the inflorescence. D. cylindrical spike. Trichoconis padwickii. Fungus: Ephelis oryzae.. 8. much resembling an agarbatti. Kresek Stage/ wilt: Kresek is noticed in transplanted seedlings of one to two weeks old. Infected plants are usually stunted.. 10. Spots appear on leaf sheaths. Black. Nigrospora sp). This disease is responsible for quantitative and qualitative losses of grains. short.oryzae). In advanced stages. pedicels and glumes also. reddish brown spots appear on leaves. Lesions are also seen on the leaf sheath. 9. dirty coloured. reduced in size. . The discolouration may be red. Conidiophores are multiseptate. which extend along both the margins with irregular wavy margins. Grain Discolouration Symptoms: Dark brown or black spots appear on the grains. Phoma sp. The glumes are not affected. straight or curved tapering towards tip and 3-5 septate. They droop. Alternaria tenuis. Fungi: Many fungi (Drechslera oryzae. Fungus: Ustilaginoidea virens. rostratum.Symptoms: The disease appears on the earhead where individual ovaries are transformed into large. ii. tetramera. Fungus: Cercospora janseana (C. Sarocladium oryzae. The young smut spores (chlamydospores) are almost round and smooth but when mature they become warty and olive green. Udbatta Disease Symptoms: The earheads are affected. Long axis of these spots is parallel with the veins of the leaf. Cladosporium herbarum. Curvularia lunata. Infected leaves become greyish green. The panicle emerges as a straight. convex pycnidia are immersed in the stroma. depending upon the organism involved and the degree of infection. yellow. Pycnidiospores are hyaline. Cephalosporium sp. pink or black. orange. D. hard. cylindrical. Conidia are hyaline to subhyaline. Epicoccum purpurascens. 11. not branched and geniculate. Fusarium moniliforme. velvety greenish spore balls. The spore balls may reach one cm or more in diameter and enclose floral parts. Narrow Brown Leaf Spot Symptoms: Narrow. the entire leaf is blighted and dry up. aerobic. aerobic. They enlarge lengthwise and also advanced laterally over larger veins and turn brown. non-spore forming. Bacterial zone can be seen on the surface of the lesions / streaks. The virus is transmitted by the green leaf hoppers viz. RTBV has circular double stranded DNA and RTSV has single stranded RNA. nigropictus transmit this disease. The bacterium is rodshaped. The discolouration and rusty blotches spread downwards from the leaf tip. malayanus. Yellow Dwarf Symptoms: Plants become chlorotic and stunted. The young leaves may show a mottled appearance whereas older leaves appear rusty. the water becomes turbid 12. The panicles are small in size and sterile. N cinctures and N. non-spore forming and it is motile by single polar flagellum. Nephotettix virescens. The affected plants will look like a clump of grass. The cut diseased leaves can be placed in a test tube with water for a few minutes. when immersed in clear water.. Gram-negative. Bacterial ooze can be seen from the cut end of the infected leaf. N. parvus and Recilia dorsalis in a non-persistent manner. Bacterium: Xanthomonas oryzae pv. The root development is very poor. In severe cases. the leaves may dry up. N. Green leaf hoppers. Confirmation test for Bacterial leaf blight In the field. Gramnegative. Causal agent: : Phytoplasma. 13. diseased leaves can be collected and cut near the lower end of the lesions. Large number of thin and pale tillers with yellowish green leaves is seen. Nephotettix virescens.oryzae. Bacterial Leaf Streak Symptoms: Fine translucent streaks are found on the veins. 14. After 1-2 hours. The cut portion can be observed against the light to see the bacterial ooze streaming out from the cut ends into the water. non-capsule forming and monotrichous. Bacteria are rod-shaped.Bacterium: Xanthomonas oryzae pv.oryzicola. WHEAT 1. Black Rust / Stem Rust . Tungro Symptoms: The affected plants exhibit extreme stunting and discolouration of leaves ranging from various shades of yellow to orange yellow or brownish yellow. Causal agent: Two Viruses – RTBV (Rice Tungro Bacilliform Virus) and RTSV (Rice Tungro Spherical Virus). Infected plants take longer time to flower and mature. thin . golden brown. The stalk or stem is often most severely affected. smooth. The basidiospores are unicellular. round or oval orange sori. brown pustules on the stem. spikelets and glumes and also on grains in severe infections. hyaline. thick walled. leaf sheaths. leaf sheath and leaves. The uredospores are oval in shape. unicellular and uninucleate. Telial stage also occurs intermingled as black sori. dark brown. The promycelium (basidium) is long. Each spikelet is covered by a thin silvery membrane. Orange pustules represent uredosori. stem. Telia develop in the same sorus or independently. 2. the affected plant looks sickly and fails to form normal earheads. two celled. Loose Smut Symptoms: Disease is seen in the earhead stage. The teleutospores are two celled. brown. These pustules burst early exposing the brown powdery mass of uredospores. requiring two host species to complete the life cycle. pedicellate and spherical in shape. This is heteroecious rust. In severe infection. These spores are called repeating spores and cause secondary infection in the crop. Yellow Rust / Stripe Rust Symptoms: The rust pustules are bright yellow on the leaves. usually all spikelets are affected and transformed into a mass of black powdery spores. Fungus: Puccinia striiformis. Pycniospores are spherical. This is also heteroecious rust. minutely echinulate. thick walled. The aecial and pycnial stages occur on barberry plants (alternate host). thick walled at the apex and somewhat pointed at the tip with a slight constriction at the septum. They are flask-shaped and ostiolate. black and mainly seen on the stem. Uredospores are unicellular. Teleutospores are two celled. The uredospores have four equatorial germ pores. oblong. The aecia are produced on the lower surface of barberry leaf. brown and with a rounded and thickened apex. They are cup-like and thick walled. The sori are arranged in linear rows between the veins of the leaf and hence the ‘stripe rust’. They are elongated.walled. The grains are smaller. Fungus: Puccinia recondita. shriveled and lighter in weight. thick walled. 4. thin walled. Fungus: Puccinia graminis tritici.Symptoms: The onset of the disease is first marked by eruption of elongated. irregularly distributed mainly on the leaves and leaf sheath. The powdery mass of spores is blown off by wind or removed by rain leaving behind only the central rachis. 3. echinulated and has six germ pores. Brown Rust / Orange Rust / Leaf Rust Symptoms: Appearance of minute. Uredospores are unicellular yellow spherical or oval. Alternate host is Thalictrum sp. echinulated and pedicellate. hyaline and four celled. hexagonal. echinulated and pedicellate with 6-16 germ pores. . thick walled and flattened at the top. round and uninucleate. This is heteroecious rust. Aeciospores are unicellular yellow. The pycnia are produced on the upper surface of the barberry leaf. The teleutospores are dark brown. which breaks while the earhead emerges. Each spore ball contains 1 to 6 brown. the powdery growth turn into dark grey and finally black. causing lesions of varying sizes. oval to oblong spots appear on leaf blade and leaf sheath. Flag Smut Symptoms: The fungus attacks leaf. leaf sheath and inflorescence. Powdery Mildew Symptoms: A greyish white powdery growth appears on the upper surface of the leaf. Each ascus contains eight oblong. few grains are partially converted into black powdery mass enclosed by the pericarp. Fungus: Helminthosporium sativum. minute. and single celled and thin walled. The spores are aggregated into balls consisting of a dark fertile centre. . Grain formation is poor. olive-brown. Later. They enlarge. smooth walled spores. hyaline and ectophytic. In the seedling yellowish. Conidia are produced in chains on short conidiophores. Fungus produces olivaceous conidiophores which bear conidia. tritici. They germinate to produce 3 to 4 basidia. basal portion slightly tapered and the distal portion hemispherical. Embryo is not affected and such grains can germinate. the affected leaves dry up. echinulated smut spores (chlamydospores) in the affected earheads. Fungus: Erysiphe graminis var. Greyish black linear sori occur on the leaf blade and leaf sheath. surrounded by a ring of lighter coloured sterile cells. globose. Fungus: Urocystis agropyri. Mycelium is septate. 8.Fungus: Ustilago nuda tritici. 6. The conidia are cylindrical. turn dark brown and cause blighting. Fungus: Neovossia indica. 7. 5. hyaline and thin walled ascospores. Each basidium in turn produces 3 to 4 basidiospores at the tip. The cleistothecia bear short appendages and produce cylindrical to oblong asci. Karnal Bunt Symptoms: The disease occurs when the grains develop in the earhead. the leaf blade becomes twisted. Teliospores are dark brown. elliptical. Conidia are hyaline. In severe cases dwarfing and reduction in internode length are seen. spherical to oval. Spores germinate to form a short stout promycelium at the apex of which a whorl of 60 to 185 sporidia are formed. Leaf Spot Symptoms: Seedlings and matured plants are attacked. 2-11 septate. With advancement of the disease. It produces unicellular pale. Inflorescence development is arrested. The sorus contains black powdery mass of spores. spherical to oval with reticulations on the epispore which appear as curved spine. stem and earheads. Questions to be answered 1. Chocking of panicle is observed in __________ disease 6. Which stage of BLB infection causes highest damage to the crop? . 11. Name a rice pathogen which produces chlamydospores. the leaf sheaths turn blackish brown and split into shreds. Which stage of blast infection causes highest yield loss to rice crop? 2. 4. The bacterium is rod shaped. Foot Rot Symptoms: The disease mainly occurs in seedlings and roots and rootlets become brown in colour. 10. Galls formed by the nematodes replace most of the grains in the earhead. arrhenomanes. 10. Conidiophores are produced through stomata bearing conidia singly or in chains of 2 to 4. Blast fungus produces _____________ shaped spots on rice leaves 3. Mycelium is hyaline. light brown to dark olive-buff and multicellular with 1to 10 transverse septa and 0 to 5 longitudinal septa. pleomorphic and frequently exhibit club shaped swellings. Fungus: Alternaria triticina. The fungus produces sporangia. Tundu / Yellow Ear Rot Symptoms: The characteristic symptom of the disease is the formation of yellow slime on the stem and inflorescence. oval. zoospores and oospores. An example for internally seed-borne rice pathogen. Write an example for soil-borne rice pathogen 8. It dries up to form sticky yellow layers and cause curling and twisting of the spikes. Gram positive and motile by a polar flagellum. 7. Fungi: Pythium graminicolum and P. A collateral host for blast pathogen is _______________ 5.9. Seedlings become pale green and have stunted growth. branched and septate. The collar region becomes discoloured and soft. Name two rice pathogens which produce sclerotia. Several spots may coalesce to cover larger areas of the leaf to cause blighting. The mycelium is dull brown. unbranched and erect. Causal organisms: Corynebacterium tritici (Bacterium) and Anguina tritici (Nematode). Conidia are smooth. Heavily infected fields display a burnt appearance from a distance. . Leaf Blight Symptoms: The fungus produces reddish brown spots with bright yellow margin. septate. nonseptate and inter – and intracellular. Which pathogen is responsible for growth promotion in rice? 9. The repeating spores of wheat rust pathogen is ________________ 15. Sheath blight and Sheath rot 2. The nematode associated with yellow ear rot of wheat is ___________ True or False 1. 3. The alternate host for Puccinia recondita is _____________ 18. the infection usually appears in sheath which encloses panicle. Karnal bunt and Common bunt 8. Sheath rot and Foot rot 3. The foul smell in bunt disease of wheat is due to _____________ 21. Bacterial leaf blight and Bacterial leaf streak 7. Brown spot and Narrow brown leaf spot 5.11. Blast and Brown spot 4. Black rust. RTD is caused by _______________ 13. Pathogen which causes false smut in rice spreads through soil. Karnal bunt of wheat is a seed-borne disease 7. Flag smut and loose smut . Sarocladium oryzae is a seed-borne pathogen. The diagnostic test used for identifying BLB / BLS infection in rice is _______ 12. Barberry act as an alternate host for _______________ 17. Diagnostic test for RTD is _____________ 14. 4. RTD causes sterility in rice crop 5. brown rust and yellow rust 9. Ustilago nuda tritici is an internally seed-borne pathogen in wheat 6. Sexual fruiting body wheat powdery mildew pathogen 19. Rice tungro disease and Yellow dwarf 6. 2. Teleutospores of Puccinia are _______ celled 16. Name one soil-borne pathogen infecting wheat crop 20. seed and air. In sheath blight. The conidia of wheat powdery mildew is oidium type Differentiate 1. dirty grey. Short Smut / Grain Smut / Covered Smut/Kernel Smut Symptoms: The disease becomes apparent only at the time of grain formation in the earhead. 2. The space in between the sorus wall and columella is filled with large number of chlamydospores. hard central tissue called columella. more tillers and malformed spikelets in the earhead. Sphacelotheca sorghi).Ex. having a tough wall and a long. which often persists unbroken up to threshing. produce thinner stalks. The fungus is present in the form of sorus which is cylindrical. Maize. They are larger than the normal grains. 2 Date: DISEASES OF MILLETS (Sorghum. No. They are often united into loose balls which break up into individual spores when placed in water. Pearlmillet and Ragi) SORGHUM 1. Fungus: Sporisorium sorghi (Syn. The Smut spores are round or oval. Individual sori are oval or conical and are covered with a rough white or cream to light brown skin (peridium). sac-like structure. Most of the grains are transformed into smut sori. Earheads come out earlier. Loose Smut Symptoms: The affected plants are shorter. smooth and thick walled. Normally all . olive brown singly and in mass appear dark brown. Fungus: Tolyposporium ehrenbergii. Uredospores are unicellular. The alternate host is Oxalis corniculata. Long Smut Symptoms: Few grains in the earhead are transformed into smut sori. It is heteroecious and long cycle rust. The head is either completely or partially replaced by a large whitish gall. They are globose or angular and brownish green in colour. 3. Sphacelotheca cruenta). They germinate to form a four celled promycelium with laterally borne sporidia. The teleutospores are chocolate brown. The sorus is covered by a membrane. echinulate and dark brown in colour. Uredosori are elliptical and lie between and parallel with the leaf veins. They are purple. dark coloured filaments (vascular bundles) are seen. Sori occur on rachis and branches of inflorescence also. most of the grains are transformed into sori. The membrane breaks and releases the black spore mass. 5. . The galls are at first covered by a whitish grey membrane of fungal tissue which ruptures before the earhead emergence and expose a mass of brown or black smut spores among which long. The spores are firmly united and form spore balls. Sporisorium reilianum. Fungus: Puccinia purpurea. reddish brown to black with finely echinulate spore wall. The sorus replaces the stamens and pistil. In severe case. Rust Symptoms: The rust appears as small flecks on the lower surface of the lower leaves. Fungus: Sporisorium cruentum (syn. there is a bundle of brown filaments. two celled and constricted at the septum with rounded apex. The fungus produces smut sori filled with black masses of spores. which are angular to spherical. which are scattered in the earhead. 4. Head Smut Symptoms: The disease becomes apparent only at the time of flowering. slightly curved and is much longer than the other smuts. thin. dark brown with echinulated spore wall. Later it spreads to other leaves. They rupture and release powdery mass of uredospores. elliptical. Inside the sorus. Fungus: Sporisorium holci-sorghi (syn. The fungus is present in the form of spores enclosed by the thin sorus membrane. The affected earheads are looser than the normal ones. Smut spores are spherical to elliptical. The fungus is systemic in the host plant and produces chlamydospores or smut spores. Teleutosori are dark coloured and longer than the uredosori. elliptical or oval. having columella at the centre of the sorus. tan or red coloured depending on the cultivar. The pustules may occur on leaf sheaths and inflorescence stalks also. pedicellate.florets of infected heads are smutted. cylindrical. Sphacelotheca reiliana). long. dark brown and round. Mycelium is septate. globose. 8. Setae are long. obclavate and three to many septate. Anthracnose / Red Leaf Spot / Red Rot Symptoms: Fungus causes small. Conidiophores are brown and emerge in clusters through stomata. Fungus: Cercospora sorghi. The lesions increase in size even to the entire length . purple or tan margins. Sporangia are single celled. single celled and sickle shaped conidia. simple or rarely branched. Downy fungal growth can be seen on the lower surface of the leaf and even on the upper surface in severe cases. purple. Hyphae are intercellular and non-septate and send branched haustoria into the host cells. Fungus: Colletotrichum graminicola. geniculate and 0 to 5 septate. red or purple lesions on which black acervuli are seen. They occur on the leaf blade and sheath. oval and reddish spots with straw coloured centre and red. Several spots coalesce together and kill large patches of the leaf blade. Downy Mildew Symptoms: The infected plants tiller excessively and dwarfed because of shortened internodes. Acervuli with setae arise through epidermis. Sporangiophores arise through the stomata and branch irregularly to produce sterigmata bearing sporangia. Oospores are produced at the later stages in shredded leaves. As the disease advances the leaf becomes shredded lengthwise (leaf shredding). with straw coloured centre and dark margin appear on the leaves. hyaline. The fungus produces large number of short hyaline conidiophores which release hyaline. pointed and black. It is an obligate parasite. The colour varies with the varieties. Conidia are hyaline. They are thick walled. Leaf Blight Symptoms: Long elliptical necrotic lesions. thin walled. Infected stems when split open show discolouration. 9. The spots are red. dark red to purplish in colour. Several spots merge together and form bigger lesions. Severe spotting causes drying of leaves.6. which may be continuous over a large area or more generally discontinuous. elliptical. particularly in the inflorescence. thin walled and lack papilla. giving the stem a marbled appearance. Leaf Spot Symptoms: Spots are rectangular to irregular. brown or straw coloured and are slightly sunken in the middle with lighter colour. The leaves become pale and chlorotic with broad streaks extending from the base to the tip. hyaline or light brown coloured and intercellular. rigid. Fungus develops systemically in the host plant. Black dots of acervuli are seen on the centre of the spots. 7. Red rot phase occur in stalks and/or in the inflorescences and is characterized externally by the development of circular cankers. Fungus: Peronosclerospora sorghi. Midrib infection is seen as elongate. of the lamina with 1 to 2 cm width. Head Smut . long. Witch weed is a partial root parasite and occurs mainly in the rainfed sorghum. Fungus: Claviceps sorghi (Sphacelia sorghi). straight or curved. Helminthosporium turcicum. gives the head a blackened appearance. cream to light brown hard sclerotia develops in the infected spikelets. black and 2. perfect stage: Trichometasphaeria turcica). straight or slightly curved and many septate. Mycelium is septate. Fungus: echinulate. long. ears and tassels. Parasite: Striga asiatica and S. It always occurs in clusters of 1020 / host plant. the galls breakdown and release black masses of spores. densiflora produces white flowers. The fruit is a capsule and each fruit contains about 1000 seeds. The parasite becomes visible in about a month after sowing. It is a small plant with bright green. The infected plants are stunted and lanky in growth and may die prior to seed setting. A single plant can produce one to five lakhs seeds. narrow leaves. The sclerotia are cylindrical. Large number of single celled. The disease is most severe in young actively growing plants and may stunt or kill them. several lesions cause blighting of the leaf. Phanerogamic Parasite – Witch Weed Symptoms: The root exudates of sorghum stimulate the seeds of the parasite to germinate. straight or bent. leaves. spindle shaped. Conspicuous closed white galls replace individual grains. Under favourable conditions 1-2 cm long. Conidia are brown to dark brown. grows up to a height of 15-30 cm. thin – walled conidia are seen in the honey-dew. The parasite then slowly attach to the root of the host by haustoria and grow below the soil surface and produce under-ground stems and roots. Sugary Disease / Ergot Symptoms: Secretion of creamy sticky liquid (honey dew) from infected florets is seen. Fungus: Exserohilum turcicum (syn. straight or curved. Colonization by Cerebella sp. which will infect maize plants in the following season. septate. coloured and internal. In severe cases. S. At times. 10. Ustilago maydis. 11. The spores are spherical to ellipsoidal. Severe infestation causes yellowing and wilting of the host leaves. densiflora. asiatica produces red to pink flowers while S. They are simple olivaceous. Conidiophores arise through stomata in groups. MAIZE 1. hard and black. elliptical to oblong. hyaline. Common Smut Symptoms: The fungus attacks stalks. Mycelium is septate. which are angular to spherical. 3. Fungus: Puccinia sorghi. The stem rots and breaks at the infected point causing lodging. thick walled and deep brown.. The teleutospores are two celled. Brown Spot Symptoms: Fungus produces water-soaked lesions. 4. Several spots may coalesce to form brown blotches. stricta. reddish brown to black with finely echinulate. Later. thin-walled. chlorotic yellowish stripes appear on the leaves and the stripes are delineated by veins. b. Fungus: Peronosclerospora sorghi (Syn. It also occurs on the leaf sheath and stem. Uredospores are echinulate and yellowish brown. The spots on the midrib are circular and dark brown.Symptoms: The most conspicuous symptoms are a. The pustules are brown when young and are surrounded by chlorotic haloes. spore wall. The aecial stage is produced on three species of Oxalis. Oxalis corniculata. masses of black spores which also grow instead of the normal earhead. As the disease advances. When the stem is infected the tissues are weakened. abnormal development of tassels which become malformed and overgrown. The fungus produces numerous hyaline. In advanced stages. Rust Symptoms: It is common when the plants approach tasseling. rounded at the apex and dark brown in colour. They are light green at first which turn to reddish brown and finally to brown. viz. The fungus is systemic in the host plant and produces chlamydospores or smut spores. O. Sclerospora sacchari). Sphacelotheca reiliana). oospores are formed which are spherical. leaving the vascular bundles exposed and shredded. The sporangia are spherical and lack apical papilla. browning and necrosis of the leaf blade and stunting of the affected plants. the sori turn black in colour. . These stripes later turn brown or straw coloured and become necrotic. Minute round to elongated pustules occur on both leaf surfaces and sometimes on the husk and other floral parts. Downy Mildew and Crazy top Symptoms: The fungus produces a characteristic downy growth on the leaves followed by yellow discolouration. slightly constricted at the septum. These spots and blotches are found at the basal portion of the leaf blade. In severe cases plants look unhealthy. 5. europaea and O. As the disease advances the pustules are found scattered all over the leaf blade and the leaves wilt ultimately. Fungus: Sporisorium reilianum (Syn. elliptic or oblong sporangia on dichotomously branched sporangiophores. black masses of spores which develop inside individual male florets and c. Proliferation of axillary buds on the stalk of tassel as well as cobs is very common producing the crazy top symptom. 6. Fungus: Helminthosporium turcicum (Syn. Downy Mildew / Green Ear . and pale to dark golden brown with 5-11 pseudosepta. black sclerotia are seen. When plants approach maturity internal parts of stem show black discolouration and shredding of vascular bundles. They grow into elongated spindle shaped necrotic lesions. They are smooth. Resting sporangia germinate and produce uniflagellate zoospores. Fungus: Macrophomina phaseolina sclerotia. The affected plants develop wilting symptoms and they gradually dry up. PEARL MILLET 1. watersoaked small spots on the leaves. On the rind and vascular bundles of infected plant numerous small. The pycnidiospores are colourless. Mycelium is branched. Conidia are distinctly curved.Fungus: Physoderma zeae-maydis. They appear first on the lower leaves and continue increasing in size and number until a complete burning of foliage is seen. Pycnidia appear on the stalks. Charcoal Stalk Rot Symptoms: The pathogen invades seedling roots. 7. These symptoms are common mainly in lower stalk internodes. oval and single celled. brown and flattened at one side. Leaf Blight Symptoms: The disease is recognized by the production of slightly oval. yellowish brown and smooth. the fungus produces large number of round and black sclerotia. Drechslera turcica. geniculate. The fungus produce coenocytic hyphae and large number of thick walled spore-like bodies called resting sporangia or resting spores. fusiform. septate and inter and intra cellular. long. unbranched. Exserohilum turcicum. Conidiophores arise in group. septate. two celled. Infected leaves and inflorescences produce sporangia. stout. elliptic or pyriform having echinulate spore wall and are with four equatorial germ pores. producing intercellular. non-septate basal portion from which a few stout irregular branches arise. The pycnia are formed on the upper surface of the brinjal leaf. Sporangia are hyaline. thin walled and by germination each sporangium releases 3-12 zoospores. producing the uredial and telial stages on pearlmillet and the aecial and pycnial stages on brinjal. one from each cell. They are dark brown. The teliospores germinate to produce four-celled promycelium and four basidiospores. It develops systemically. They have a short. The first leaf that has symptoms is normally partially infected and subsequent leaves emerge with progressively more infection until leaves emerge with complete discolouration. Rust Symptoms: The minute round reddish brown uredopustules occur in groups on both the surfaces of the older leaves and on the leaf sheath and stem. papillate. crowded with sterigmata. Puccinia penniseti). Inflorescences are completely or partially malformed with florets and their parts converted into leafy structure (Green ear). It is an obligate parasite.Symptoms: Infection is systemic and symptoms appear on leaves and inflorescences. Fungus: Sclerospora graminicola. The fungus is macrocyclic rust. penicillariae (Syn. . The pycniospores are oblong or elliptic and hyaline. broadly elliptical. Symptoms first appear in seedlings at 3-4 leaf stage where leaves become chlorotic or yellowish with profuse white growth of the fungus on the lower surface. The uredospores are yellowish brown. They are spherical. As necrosis starts in the plant parts oospore production is seen. thick and smooth walled and yellowish brown. The oospores are present in the interveinal areas of leaves. The teleutospores are divided by paraphyses. club shaped and has single germ pore for each cell. They are borne singly on pedicels mixed with paraphyses. bearing pycniospores and receptive hyphae. The cup-like aecia occur on the lower leaf surface of the alternate host (brinjal) bearing aeciospores in chains. sending haustoria into the host tissue. Seedling dies within 30 days and do not tiller. 2. hyaline. oval. Fungus: Puccinia substriata var. As the 33disease advances teleutosori are produced which are dark-brown merging with one another causing linear patches or lesions. non-septate hyphae. The sporangiophores arise through the stomata bearing sporangia on the sterigmata. Sclerotia are large and appear creamy during early stage and become black and hard at maturity . first dark at the tip and then becoming completely black. Smut Symptoms: The disease becomes apparent at the time of grain setting in the earhead. fusiform and single celled. Fungus: Claviceps fusiformis (Syn. dark coloured hard structures called sclerotia develop from infected florets. The pathogen infects florets and transforms them into large plumby seeds (sori) containing black powder of smut spores. Individual teleutospores do not separate readily and are mostly angular or round and light brown.3. The number of teleutospores aggregated in balls varies from 200 to 1400. As the sori mature. globular and single celled. The fungus produces micro-and macroconidia. Honeydew contains millions of conidia. Subsequently long. Mycelium is septate which produce closely arranged conidiophores. The sorus wall is tough and surrounds spores. while the microconidia germinate by producing only one germ tube. 4. The microconidia are hyaline. they become dark brown and are easily broken to release millions of black smut spore balls. C. The macro conidia germinate. Fungus: Tolyposporium penicillariae. Young sori are larger and greener than non-infected developing seed. The macroconidia are hyaline. The spores are usually in balls. They germinate in water to produce four celled promycelium bearing the sporidia. microcephala). Sugary Disease / Ergot Symptoms: The pathogen infects the florets at the protogyny stage and develops in the ovaries and produce initially copious creamy pink or red sweet sticky liquid called honeydew. by producing one to three germ tubes. At the centre of the spots. Conidiophores are long and septate. light grey bloom of conidiophores and conidia are seen. Such earheads bear only chaffy grains. The margins are dark brown and the centre is light coloured. They are simple. Blast Symptoms: Young seedlings may be blasted or blighted in the nursery bed. The mycelium is septate and hyaline and turns brown with age. Fungus: Pyricularia grisea. Each lesion has a chlorotic yellow halo.SCLEROTIA 5. The neck infection causes breaking of the heads. The fungus produces characteristic spindle shaped spots with yellow margins and greyish green centres on the leaves of grown up plants. Fungus: Pyricularia setariae. RAGI 1. Later the centres become grey or whitish grey. . Leaf Blast Symptoms: Lesions on leaf blade are roughly diamond shaped to circular up to 1 cm long. hyaline to pale olive green and three celled. Mycelium is hyaline to olivaceous and septate. Fungus causes blackening of the nodal regions. Conidia are obpyriform to ellipsoid and attached at the broader base by a hilum. The conidiophores emerge through stomata. Smut Symptoms: Only few grains in an earhead are infected. The affected grains are converted into enlarged globose sacs. maize. but later become dirty black. The earhead bears abnormal spikelets exhibiting various degrees of proliferation instead of normal spikelet. The ascospores are spirally coiled. branched and non-septate. 3. Dactyloctenium aegyptium. Japanese barnyard millet. Green Ear / Downy Mildew / Crazy Top Symptoms: The infected plants are dwarf with shortened internodes. The oospores are globose and thick walled. They are hyaline. hyaline. oval spot leading to premature withering. Conidia are straight. The spots on the leaf sheaths and culms are irregular and are generally found at the junction of leaf blade and sheath. roots etc. while rice and Digitaria marginata are not infected. 5. Hyphae are light brown. Conidiophores are dark brown. The leaves are closely arranged and give bushy and bunchy appearance. and pale to dark golden brown and up to 18 septate. The fungus can attack Eleusine indica. light brown. geniculate and septate. oats and Dactyloctenium aegyptium. Cochliobolus nodulosus). Asci are short. thick walled and septate. ovoid. spiny or pitted spore wall. and cylindrical and 1-8 spored. Mosaic . Sexual stage. On young leaves of seedlings disease appears as minute. Drechslera nodulosum. dark coloured at the base and lighter above. Infection of the neck causes discolouration and sooty growth in the inflorescence. fox tail-millet. dark brown spots appear on the leaves. maize. Conidia are obpyriform. greenish at first. The hyphae are inter-cellular. Fungus: Sclerophthora macrospora. three celled with a prominent hilum. Perithecia are black and spherical. sorghum and sugarcane. thin walled. leaf sheath. The leaves are pale. pearlmillet. 2. Seedling Blight / Leaf Blight Symptoms: The pathogen attacks leaf blade. The fungus attacks fox tail millet. straight. Fungus: Melanopsichium eleusinis. Fungus: Helminthosporium nodulosum (Syn. barley. branched. culms. The whole earhead gives a bush-like appearance. filiform and 11 septate. pearl millet.septate. pros millet. Eleusine indica. The spores are globose with a rough. wheat. In grown up plants. oblong. 4. In Sorghum. 2. Name two host plants which are infected by Peronosclerospora sorghi True or False 1. which pathogen produces spores in ball? 3. Teleutospores are normally produced at the end of cropping season. The loss in grain yield may be as high as 100 per cent. Anamorph of Claviceps sorghi is _____________ 9. Transmission of the virus is through sap and insect 6. Pycnial and aecial stages of Puccinia purpurea are produced in ______________ 4. dwarfed and sterile. When the plant is infected. Leaf shredding disease in sorghum is caused by ______________ 5. The entire plant becomes pale. Aphis maydis. The affected plants rarely come to flowering and if earhead is formed the panicle will be mostly chaffy. cinai. Causal agent: Virus. Causal agents: and C. Sclerospora graminicola is systemic pathogen 3. Brinjal is an alternative host for pearlmillet rust .Symptoms: It produces most prominent symptoms from 4 to 6 weeks after planting. tillering and grain formation are reduced. Fungal genera which produce conidia on geniculate type conidiophore are _____ 8. Asexual fruiting body of anthracnose fungus is ________________ 7. The sexual spore of downy mildew fungus is ______________ 6. Mottle Streak and Streak Symptoms: Diseased plants are stunted and pale green. The symptoms are chlorosis followed by mosaic mottling and severe stunting. Two stages of ergot disease is _____________ and ___________ 10. What is sorus? 2. Chlorotic streaks appear on the leaves and it is continuous in streak disease and discontinuous in mottle streak disease. Viruses. vector. The viruses are transmitted by Cicadulina bipunctella Questions to be answered 1. Ergot and smut of pearlmillet 2. Early symptoms on stems and branches are spindle shaped lesions with light grey centres and brown margin with scattered pycnidial bodies. The leaves of affected plants turn yellow prematurely. single or in chains. Greengram and Chickpea) REDGRAM / PIGEONPEA 1. When such plants are uprooted their roots are rotten and shredded. Wilt Symptoms: The most characteristic symptom is a purple band extending upwards from the base of the main stem. and thin walled and single or two celled. 2.Differentiate 1. the foliage droops and within three or four days the plants wilt. 3 Date: DISEASES OF PULSES (Pigeonpea. Dry Root Rot Symptoms: Infected plants suddenly and prematurely dry up. The fungus produces both macro-and microconidia. No. Smut diseases of sorghum 4. When the young plants (1-2 months old) die from wilt they may not show the purple band symptoms. . Downy mildew of sorghum and pearlmillet 3. Common smut and head smut of maize 5. The microconidia are small. septate and both inter-and intracellular. but have obvious internal browning and blackening. Blackgram. Pycndia and pycnia Ex. curved. The macroconidia are linear. pointed at both ends and thin walled having 3-4 septa. Browning of the stem tissue in the region of the purple band and browning or blackening of xylem vessels when the main stem or branches is split open are other typical symptoms. elliptical. Fungus: Fusarium udum. The chlamydospores are oval or spherical. humid conditions root rotting extends to the base of the stem. The mycelium is hyaline. Under hot. terminal or intercalary. irregular necrotic blotches develop and premature defoliation occurs. Mycelium is hyaline and coenocytic. which produces single celled. The corresponding upper surface become chlorotic and then turns yellow. The spots increase in size and cover a major portion of the lamina. clavate or club shaped conidium. short. They are long. smooth. endophytic and intercellular. The fungus causes stunting of young plants. minute and globose. Leaf Spot Symptoms: The spots on leaves are small. In leaf. Infected tissue becomes soft and whole plant wilts. Conidiophores are hyaline. later enlarging and slightly depressed. obpyriform to cylindrical and develop from the inner walls of the pycnidium. Fungus: Leveillula taurica. ovate or pyriform and non-papillate. .Fungus: Macrophomina phaseolina. hard. The pycnidia are dark brown. smooth and thick walled. The fungus produces haustoria in epidermis and in spongy parenchymatous cells. Powdery Mildew Symptoms: Fungus attacks the leaf.sp. 5. light brown later it becomes dark brown and the infected portions drop off leaving shot hold symptoms. leading to drying. 3. rarely branched and septate. localized yellowing starts from tip and margin and gradually extends towards the mid-rib. light brown. septate. When several spots join together. Sclerotia are jet black. Fungus: Phytophthora drechsleri f. The fungus produces dark brown filamentous hyphae and constrictions are seen in hyphal branches at the junction with the main hypha. single celled and ellipsoid to ovoid. pycnidiospores are hyaline. Each sporangium produces 8-20 zoospores. Flowers and pods are also affected on which white powdery fungal growth can be seen. Sporangia are hyaline. Stem Blight / Phytophthora Blight Symptoms: Initially purple to dark brown necrotic lesions girdle the basal portion of the stem and later may occur on aerial parts of the seedlings. Initially lesions are small and smooth. Oospores are globose. 4. Conidiophores arise from the internal mycelium singly or in fascicles through stomatal apertures. cajani. Mycelium is hyaline. covering it with powdery whitish growth on lower surface causing premature defoliation. The centre of the spots later turns brown and hard. The diseased plants remain green till harvest. Water-soaked lesions appear on the pods. The affected parts may wither off. hyaline and 7-9 septate. A few dark coloured septate setae are seen in the acervulus. Dark lesions may be seen on the bark at the ground level. Conidial or pycnidial stage is produced on the host. 6. hyaline. They are smooth. Conidiophores are light brown when young and dark brown when mature. Conidia are cylindrical. The basal stem and the main roots may show dry rot symptoms. crinkled small with mosaic symptoms.Fungus: Cercospora indica. BLACKGRAM AND GREENGRAM 1. . 2. 3Conidia are whip like. Rhizoctonia bataticola). The fungus produces both inter-and intracellular mycelium. Mycelium is dark brown. The disease is transmitted by the eriophyid mite. thin walled and single celled. The entire plant is stunted with shortened internodes. The leaves are crowded and the axillary buds are stimulated resulting in a bushy growth. The mycelium is septate. hyaline and branched. Small angular brown lesions appear on the leaves. later becoming brown and enlarging to form circular spots of varying size. The lesions may be seen on petiole and stem also. Causal agent: Virus. The spots are usually depressed with dark centres and bright – red. round and black. branched and septate. Mycelium is inter-and intracellular. Sterility Mosaic Symptoms: The diseased plants show malformed leaves which are thin. yellow or orange margins. Within a day or two such leaves droop and finally they may drop-off. Conidiophores are hyaline. Fungus: Macrophomina phaseolina (syn. Aceria cajani. The diseased plants are invariably sterile causing severe losses in grain yield. The plants may wilt within a week. which later become spots with greyish white centre and dark brown margin. The tissues are weakened and break off easily. Anthracnose Symptoms: All aerial parts of the plants are affected. It produces numerous sclerotial bodies on the host tissues. Dry Root Rot Symptoms: Symptoms first appear as yellowing of leaves. short and unbranched. mostly adjacent to veins. Fungus: Colletotrichum lindemuthianum. canescens produces dark and long. straight or curved. In severe cases. petiole and stem. straight or slightly curved multiseptate conidiophores. single celled and thin walled. black. Mycelia are both inter-and intracellular in the host tissue. unicellular. Uredospores are unicellular. hyaline. In severe cases the entire plant dries up. borne singly at the tip of the conidiophores. circular spots develop on the leaves with grey centre and brown margin. lesions are developed on stems and pods. elliptical or barrel shaped. elliptical and single celled. Leaf Spot Symptoms: Small. In severe infections the leaf may wither resulting in considerable damage to the crop. Conidia are hyaline.Pycnidia are dark brown and ostiolate. Fungus: Uromyces phseoli-typica (Syn. orange coloured and aeciospores are unicellular and elliptical. The pustules are mostly found on the leaf blade. The pustules appear as tiny light–coloured flecks or spots. Powdery Mildew Symptoms: A white powdery growth occurs on the leaves spreading to cover the stem and other plants parts. 3. hyaline and bear chains of conidia. chestnut brown with warty and with hyaline papilla at the top. single celled and elliptical ascospores. 5. Fungi: Cercospora capeskins and C. 4. cruenta. Several sori coalesce to cover a larger area of the blade. In a few days they become dark reddish-brown. appendiculatus). canescens are whip like. The fungus is an ectoparasite spreading on the surface of the host and sending haustoria into the epidermal cells to draw out nutrients. yellowish brown with echinulations. hyaline. Pycnidiospores are thin walled. . Cleistothecia are short. U. circular pustules about the size of a pinhead. Fungus: Erysiphe polygoni. thin walled and 5-6 septate. The teliospores are globose or elliptical. Each ascus contains 3 to 8 hyaline. The conidia of C. The symptoms are severe at flowering stage. As the disease advances. globoid or ellipsoid. defoliation occurs. round with myceloid appendages and bear 2 to 8 asci. Uredial stage repeats several times. Asci are ovate and sessile. The conidiophores are simple. C. Rust Symptoms: The fungus produces characteristic rust pustules both on the upper and lower leaf surfaces. Aecia are cup shaped. single celled. The fungus is an obligate parasite and autoecious in nature. Several spots coalesce to form brown irregular lesions. When the lesions are produced on stem. The virus is seed-borne and primary infection occurs through infected seeds. craccivora also transmit the disease. After a week of first symptoms crinkling of leaves becomes conspicuous later crinkling and curling of tip of leaflets are seen. one or two celled. 7. weed hosts and other cultivated hosts. Secondary spread is by the insect vector. CHICKPEA / BENGALGRAM 1. dark .gossypii and A. The petioles and internodes are shortened. Infected plants give a bushy and stunted appearance. Fungus: Ascochyta rabiei. Leaf Crinkle Symptoms: The symptoms appear initially on young leaves. It survives in the self-sown plants. the portion above the point of attack rapidly dies. Similar spots may also appear on stem and pods. Early infection causes death of plants before seed set. Causal agent: Mungbean yellow mosaic virus (MYMV).6. Causal agent: Urdbean leaf crinkle virus (ULCV). The infected plants normally mature later and bear a very few flowers and pods. Pycnidiospores are oval. Yellow Mosaic Symptoms: Initially small yellow patches appear on leaves. A. Flowering is delayed. In severe case the diseased leaves become white and thin. The perithecia are globose. Blight Symptoms: The disease symptoms appear first on leaves as water soaked lesions which later develop into round spots with brown margin and yellowish to grey centre. Bemisia tabaci. thin walled and hyaline. Bemisia tabaci. The virus is also sap transmissible. The fungus produces innumerable spherical to pear shaped pycnidia with prominent ostiole on the infected tissues. In advanced stages several spots on the leaves and pods may coalesce to blight the plant. It is transmitted by the whitefly. The yellow discolouration slowly increases and newly formed leaves may completely turn yellow. The enlargement of third trifoliate leaf is seen 4 to 5 weeks after sowing. Inflorescence if formed is malformed with small sized flower buds and flower buds fail to open. terminal or intercalary formed singly or in chains. Vascular browning is conspicuously seen as black streaks on the stem and root portion below the bark. The infected seedling slowly turn yellow and petioles and leaflets show drooping. oval. Root Rot Symptoms: A dark brown lesion develops on the stem near ground level. 3 to 5 septate. oval to cylindrical and single celled. ascospores are hyaline. browning of 3vascular bundles and finally wilting of plants. Macroconidia are thin walled. brownish yellow with echinulate spore wall with 4-8 germ pores. The leaflets are smaller with yellow. 4. Fungus: Fusarium oxysporum f. Teliospores are round to oval. Chlamydospores are rough or smooth walled. The chief symptoms in seedling are yellowing and drying of leaves from base upwards. drooping of petioles and rachis. The 2. elliptical and two celled. In adult plants. Microconidia are hyaline. Mycelium is dark brown. Fungus: Macrophomina phaseolina. Dark brown or black discolouration is noticed below and above collar region. single celled with unthickened apex and rough. The stem near the collar region and below shows rotting symptom. brown and warty wall. curved and pedicellate. Phloem browning in the collar region is the most characteristic symptom of the stunt leaving xylem normal. The black dead tissues contain sclerotia.sp. Wilt Symptoms: The disease occurs at two stages of crop growth. Uredospores are spherical. Stem also shows brown discolouration. . orange or brown discolouration. filamentous and septate. Asci are cylindrical. Mycelium is hyaline and septate.brown or black and ostiolate. The fungus produces uredial and telial stages on Bengal gram. Fungus: Uromyces ciceris-arietini. ciceri. 3. brown. brown raised lesions on both the surfaces of leaves and more on lower surface. Rust Symptoms: The disease appears first as small. drooping of leaves is observed initially in upper part of plants and soon observed in entire plant. seedling stage and flowering stage. thin walled. Severely infected plants dry up prematurely. The sclerotia are brown or black and irregular or round. The plants dry prematurely. 5. fusoid and pointed at both the ends. Uredosori appear in large numbers as the disease advances and the entire leaf area may be covered with rust pustules. Stunt Symptoms: Affected plants are stunted and bushy with short internodes. leads to complete drying of the plant. Questions to be answered 1. What is autoecious rust? Give an example 5. Asexual fruiting body of anthracnose pathogen is ___________ 4.Causal agent: Bean (pea) leaf roll virus. Name the sexual and asexual spores of Phytophthora 3. Sterility mosaic of pigeonpea and yellow mosaic of blackgram 4. It is transmitted by Aphis craccivora and A. pisum. Powdery mildew of pigeonpea and blackgram 3. Yellow mosaic and leaf crinkle of blackgram . Wilt and dry root rot of pigeonpea 2. Sexual stage of Colletotrichum lindemuthianum is __________________ 7. An example for seed-borne virus in pulses is _____________ 6. The sclerotial stage of Macrophomina phaseolina is _________________ 2. The asexual fruiting body of Macrophomina phaseolina is ________________ Differentiate 1. . thick-walled and hyaline to brown. and thick-walled and are hyaline to olive brown. Gingelly. The conidiophores are septate. smooth. The sporulating fungus at the soil surface covers affected tissues. rolfsii are seen around the affected plants at or near the soil surface imparting ‘white-washed’ appearance to the base of the affected plants. The first symptom in emerged seedlings is rapid desiccation of the entire plant. Sheaths of white mycelium of S. Advanced symptoms develop when lesions coalesce to girdle the lower stem. The sterigmata are typically in two-series i. The infected areas become water-soaked and light brown and are soon covered with black fungal spores. Leaves on affected branches become chlorotic and then turn brown as they rapidly dry out. conidia are dark brown to black. Stem rot: The symptoms of stem rot are yellowing and wilting of lateral branches. Ungerminated seeds from the soil show masses of black conidia which give them a sooty appearance. The fungus sporulates on the surface of mature pods resulting in patches of black sooty spores. Lesions develop on the stem just below the soil surface and then spread upward along the branches that will results in wilting of branches. No. globose to radiate and are in chains. the entire collar region becomes dark brown and shredded. Dead plants lend to remain upright in the row. If the main stem is attacked the whole plant shows yellowing and wilting. 2. The infected areas of the stem become shredded and the sheathing mycelium quickly produces abundant spherical sclerotia on the surface of the affected plants. Lesions on infected stems are at first light brown and later they become dark brown. As the infection progresses. Castor and Sunflower) GROUNDNUT 1. The mycelium is hyaline to subhyaline. Wilt and death of a single branch or of the entire plant may follow.e. Stem and Pod Rots Symptoms: a. Aspergillus Crown Rot Symptoms: Seeds may be attacked and killed leading to a pre-emergence rotting. . Seedling infection commonly occurs in the cotyledonary-hypocotyl region just after emergence. Post-emergence infection results in death and rapid decay of seedlings.Ex. The vesicles are globose. 4 Date: DISEASES OF OILSEEDS (Groundnut. primary and secondary. Fungus: Aspergillus niger. The mycelium is coloured. becoming more dense continuous or fleshy layer and white to grey in colour.b. The sclerotia are blue to black and spherical to irregular. Sclerotia are light brown to dark brown and subspherical. Finally they are covered with many minute sclerotia. Basidia are obovoid each bearing 2 to 4 parallel or divergent sterigmata that bear basidiospore. The roots are also affected and they rot and disintegrate. In the pods the shells as well as kernels are affected. Affected young pods show light tan coloured lesions. Dry Root Rot Symptoms: The pathogen infects ground nut and produces reddish brown watersoaked lesions on the stem just above soil level. The important characters of the basidial stage are: Hymenium is at first coarsely areolate. This is caused by the production of oxalic acid by the pathogen. 4. show light to dark brown lesions. septate and branched. Fungus: Macrophomina phaseolina. Mycelium is septate and hyaline with conspicuous branching at acute angles. Basidiospores are hyaline. They later become shredded and pods become detached and are left in the soil at harvest. Later the lesion darkens and disease spread. Fruiting structures are on upper leaf surface. 3. known as ‘blue damage’. Aethalia rolfsii). Root bark peed off when the affected plants are pulled out. . Pods are completely covered with a white mycelia mat. In the dead tissue of the plant many brown sclerotia are noticed. Pods are also attacked. The seeds from diseased pods show characteristic bluish-grey discolouration of the testa. Pod rot: Pegs colonized by S. Early and Late Leaf Spots Symptoms: a. They are dark brown in colour on the upper leaf surface where most sporulation occurs and a lighter shade of brown on the lower surface. round to point at the base and apiculate. The hyphae have clamps in the some of forks and hooks or H-like connections. Pellicularia rolfsii. Fungus: Sclerotium rolfsii (Corticium rolfsii. Black nut symptom is often noticed in between the cotyledons and cannot be seen outside. When the affected kernel is split open blacknut symptom can be seen. The early leaf spot usually has a light to dark brown center and a yellow halo. Dry rot affected plants turn black and found rotten. elliptical to obovate. The affected stem is girdled and the plant wilts. The fungal hyphae spread to form a white mat of mycelium over the kernels and later they turn grey and eventually black. Early leaf spot: Lesions are sub-circular in shape. Due to infection in the kernel the fungus grows between the cotyledons. smooth. rolfsii. Asci are cylindrical and contain 8 ascospores. where most sporulation occurs. globose. a. smooth-walled. finely echinulated. Late leaf spot . 6. Ascospores are bicelled. Late leaf spot: Lesions are circular to sub-circular in shape. Fungi: Early leaf spot . the lesions are black in colour. with two germ pores which nearly equatorial. Cercospora arachidicola: Conidiophores are pale olivaceous or yellowish brown and darker at the base and unbranched. Lesions on other parts are similar to that of early leaf spot. arise in clusters and olive brown. with rounded to acute and thickened apex. Conidia are subhyaline.When disease is severe. papillate and ostiolate. Only uredial and telial stages are known.Cercospora arachidicola (Perfect stage: Mycosphaerella arachidicola). b. Uredospores are ellipsoid or obovoid. Mycosphaerella berkeleyii). Perfect stage. Perithecia are erumpent. slightly curved and hyaline. b. Cercosporidium personatum. The conidia are hyaline to olive brown. constricted in the middle. Cercospora personata: The conidiophores are long. geniculate. often curved and 3 to 12 septate. bitunicate and 8-spored. Fruiting structures are in concentric rings on the lower leaf surface. 5. Rust Symptoms: Orange-coloured circular pustules appear on the lower surface of leaf. Perithecia are globose or ovate. Leaves infected with rust become necrotic and dry up and remain attached to the plant. straight or slightly curved and 1-9 septate. wall is brown in colour. 1-2 septate. The ascospores are hyaline and two celled. short stipitate. Fungus: Puccinia arachidis. Phoma Blight Symptoms: Light tan coloured to dark brown bigger spots appear on the leaves. On the lower leaf surface. Asci are cylindrical or club shaped. . The margin of the spots are dark brown and with central light brown coloured region. light yellow or golden yellow or chestnut brown and two-celled. All lesions are dark brown to black. Teliospores are oblong or obovate or ellipsoidal or ovate. Pustules may also formed on shells of developing pods. the upper cell some what larger. gradually attenuate at the base or more or less rounded attenuate at both ends. leaflets become chlorotic and then necrotic lesions coalesce and leaflets are shed.Phaeoisariopsis personata (Syn. ostiolate and slightly papillate. Cercospora personata. black. slightly olivaceous. Pustules are formed on the upper surface of the leaf and petiole also. obclavate. Pycnidia are pale to dark brown. the lamina is reduced to the midrib. Necrosis on older plants usually spread only to the petiole or to the portion of the stem immediately below the necrotic terminal bud. immersed. single or in chain. total necrosis of the plant is noticed. The discoloured areas expand and form large. Primary symptoms: Symptoms first appear on young leaflets as faint chlorotic spots or mottling that may develop into chlorotic and necrotic rings and streaks. dark brown or greyish with dark brown and well defined margins. Necrosis of the terminal bud soon follows. Conidia are hyaline. The early infected plants are stunted and bushy and may resemble (chlorotic) rosette. Fungus: Phoma microspora. Late-infected plants may produce seeds of normal size but the testate on such seeds are often mottled. ostiolate and immersed in leaf tissues. Only a few branches on late-infected plants are small and shriveled and their testae show red. Fungus: Didymella arachidicola. They become dry and crack irregularly. smooth-walled. Web Blotch Symptoms: Scattered tan coloured specks or streaks forming a webbed pattern are seen on the upper leaf surface. Very rarely. smooth walled. ostiolate and globose. The pycnidia are seen on the necrosed area. These blotches often coalesce and cover entire leaflets. the leaflets with initial symptoms usually become flaccid and droop. one celled. Leaflets formed on these axillary shoots show reduction in size and general chlorosis.Halo formation surrounding the leaf spot is also observed. Advanced lesions are almost black with a roughened surface. Bud Necrosis Disease (BND) a. which are less than one month old. . b. hyaline or olive brown. 8. and subglobose with rounded ends. Occasionally. giving the leaflets a “shoe string” appearance. Pycnidiospores are hyaline. circular purplish brown to dark brown blotches. which have inconspicuous margins. Mycelium is septate. globose to flask-shaped. 7. In the plants. globose or irregular. Chlamydospores are terminal or intercalary. These secondary symptoms are most common on early-infected plants and they give them a stunted and bushy appearance. brown or purple mottling. Secondary symptoms: The stunting and proliferation of axillary shoots are common. globose and one celled. Stem legions are irregular. Diseased plants can be pulled out very easily from the soil. Pycnidia are dark brown with a prominent ostiole. The sclerotia are black. occidentalis. Charcoal rot / Root or stem rot Symptoms: The pathogen attacks the stem at the collar region. GINGELLY 1. sesami. elliptical and single celled. In the later stages. The pycnidiospores are hyaline.sp. 2. F. Frankliniella schultzei. fusca. Fungus: Fusarium oxysporum f. In less severe infection few branches may develop symptoms of wilt resulting in partial wilting. The terminal portion dries up and become shrink and bent over. Abundant dot-like black structures (pycnidia or sclerotia) are produced on the inflected area. Discolouration of the vascular system is conspicuous in the roots. The fungus produces dark brown septate mycelium. Sometimes leaves in wilting plants show inward rolling of the edges and eventually dry up. Mycelium shows constrictions at the hyphal junctions. Scirtothrips dorsalis. Fungus: Macrophomina phaseolina (Sclerotial stage: Rhizoctonia bataticola). Later these streaks become black in colour. . Thrips palmi and T. F. setosus. It is transmitted by thrips like Thrips tabaci. The symptoms include yellowing of lower of leaves and drooping and defoliation of leaves. droop and desiccate. The infected portion rots and turns to a characteristic black colour. Under humid conditions pinkish growth can be seen on the discoloured area. In matured plants appearance of reddish brown discolouration of the plant from the root to the apex is the characteristic symptom of the disease.Causal agent: Tomato spotted wilt virus (TSWV). If the disease attacks mostly the plants nearing maturity. Fusarium wilt Symptoms: Leaves become yellowish. filling of pods and maturity of seeds are highly impaired. roots show rotting symptom. Asci are ovate. septate and produces large number of conidiophores. The spots on petioles are elongated and on the capsule they are more or less circular and brown to black. The fungus produces hyaline. Each ascus contains 2 to 3 ascospores. 6. twisted leaves closely arranged on the stem with very short internodes. slightly curved. The sepals .3. 4. White spot Symptoms: Small. They enlarge in size and become circular in shape and often have concentric zonation on the upper leaf surface. infection is seen on the flowers and young capsules. Alternaria leaf blight Symptoms: Reddish brown lesion is circular. Ascospores are thin walled. septate and ectophytic mycelium. Dark brown lesions on the capsules result in premature splitting with shriveled and poorly matured seeds. Conidia are hyaline. Lesions may coalesce to form large necrotic areas and defoliation results. These spots coalesce to form large patches finally covering the entire leaf surface with powdery fungal growth. Phyllody Symptoms: Affected plants are stunted and the entire plant shows phyllody symptoms. single celled and ellipsoid or barrel-shaped. light brown with simple or branched beak and borne singly or in chains of two. water-soaked and found on the foliage of seedlings. Conidia are ellipsoid. muriform (6-11 transverse septa). The calyx becomes polysepalous. Conidiophores are short and non-septate. cylindrical and light brown. Fungus: Alternaria sesami. Conidiophores are simple. The cleistothecia are dark and globose with hyaline or pale brown myceloid appendages. In severe cases. Fungus: Cercospora sesami. Seriously diseased plants shed their leaves prematurely. Lesions may spread to entire length of the stem. indistinctly multiseptate. circular 5 mm dia spots are scattered in the surface of the leaf. The most characteristic symptom of the disease is transformation of flower parts into green leaf-like structures. Conidia are hyaline. Under humid conditions the disease spreads quickly and leads to premature defoliation. elliptical and pale brown. Fungus: Erysiphe cichoracearum (Oidium acanthospermi). The spots are with whitish centre surrounded by blotch. The inflorescence is replaced by a growth consisting of short. Under favourable conditions the white mycelial growth changes to dark grey or black colour due to the formation of cleistothecia. Dark brown lesions appear on the petioles and stem. 5. The mycelium is dull brown. Powdery Mildew Symptom: The disease appears as small white powdery growth on the upper surface of leaves. Fungus: Alternaria ricini. Conidia are . Orosius albicinctus. round or oval shaped papillate sporangia at the tip singly. which are reniform and biflagellate.become leaf-like and smaller in size. which are occasionally in groups. hyaline. Phylloid flowers become actinomorphic in symmetry and the corolla becomes polypetalous and deep green. Fungus: Melampsora ricini. The chlamydospores are spherical. Often the pustules are grouped in concentric rings and coalesce together and cause drying of leaves. initially brown sunken spots appear which enlarge rapidly and cover the whole pod. Rust Symptoms: Minute. Sporangiophores are borne singly or in groups. the infection initially appears on the young leaves and spreads to petiole and stem causing black discolouration. 3. Later the spots coalesce to form big patches and pre-mature defoliation occurs. Leaf blight Symptoms: Irregular brown spots with concentric rings appear initially on the leaves and covered with fungal growth. The anthers become green and contain abnormal pollen grains. one is thick walled and the other is thin walled. They are elliptical to round. It later spreads and causes rotting. light grey to brown conidiophores. Uredospores are of two kinds. yellow and terminal or intercalary. raised pustules appear with powdery masses on the lower surface of the leaves and the corresponding areas of the upper surface of the leaves are yellow. unbranched and bear single celled. It is transmitted by jassid. The stem. In mature plants. The capsules crack and seeds are also getting infected. smooth. dull green patch on both the surfaces of cotyledon leaves. inflorescence and capsules also show dark brown lesions with concentric rings. orange-yellow coloured. orange yellow and finely warty. On the capsules. CASTOR 1. thick walled. Mycelium is hyaline and non-septate. The pathogen produces erect or slightly curved. Fungus: Phytophthora parasitica. Seedling blight Symptoms: The disease appears as circular. Causal agent: Phytoplasma. 2. The infection moves to stem and causes withering and death of seedling. Each sporangium contains 5-45 zoospores. Oospores are round and hyaline. produced in chains. They are obclavate, light olive with 5-16 cells having transverse and longitudinal septa and are with a beak at the tip. 4. Brown leaf spot Symptoms: The disease appears as minute brown specks surrounded by a pale green halo. The spots enlarge to form greyish white centre portion with deep brown margin. The spots may be 2-4 mm in dia and when several spots coalesce, large brown patches appear but restricted by veins. Infected tissues often drop off leaving shot-hole symptoms. Usually the older leaves may be blighted and withered. Fungus: Cercospora ricinella. Mycelium is inter-and intracellular. The conidiophores are with deep brown base and light brown tip, unbranched cylindrical, straight or curved and septate. The conidia are elongated, colourless, truncate at the base and narrow at the tip with 2 to 7 septa. SUNFLOWER 1. Alternaria blight Symptoms: Dark brown to black, circular to oval spots surrounded by chlorotic zone are seen on the leaves. Concentric rings are visible. Linear necrotic lesions are formed on the petioles. Under high humidity, spots enlarge in size, coalesce and cause blighting of leaves and defoliation. Rotting of flower heads is also seen. Fungus: Alternaria helianthi. Conidiophores are simple, cylindrical, straight or curved and septate. Conidia are pale green-yellow, cylindrical to ellipsoid, straight with rounded ends without beak, having 2-12 transverse septa and 0-1 longitudinal septa. 2. Rust Symptoms: Numerous small pustules (uredosori) appear on the lower surface of the bottom leaves. These uredosori are scattered, irregular, cinnamon to brown and up to one mm in dia. Infection later spreads to the upper leaves and including leaves below the capitulum. In severe infections numerous pustules appear in each leaf leading to yellowing and drying of the leaves. Telia, which are black, also seen among uredia in the lower surface of leaves. Fungus: Puccinia helianthi. It is an autoecious rust. Uredospores are ellipsoid to obovoid or cylindrical with finely echinulated wall. Teleutospores are cylindrical. Pycnia are found in groups. Aecia are in groups around the pycnia cupulate. Aeciospores are ellipsoid, hyaline with verrucose walls. 3. Head rot Symptoms: The disease occurs in the plants at heading stage and during grain formation. The affected heads show water-soaked lesion on the lower surface which later turns to brown. The infection spreads from head to stalk. In advanced cases the head becomes soft and pulpy with putrification of tissues. The insects and larvae which feed on the developing seeds pave the way for the entry of the fungi. The seeds in the diseased heads are converted into black mass and ill filled. Viability of seeds is highly reduced. Fungus: Rhizopus nigricans. Mycelium is coenocytic and has aerial branches called stolons. Sporangiophores develop opposite to the rhizoids in cluster. Each sporangiophore bears a single terminal sporangium. Sporangia are large, blackish with well developed columella. The sporangiospores are oval and pigmented and typically marked by striations. Zygospores are provided with black, thick, several layered wall. 4. Charcoal rot and root rot Symptoms: Affected seedling show a brown or ashy black discolouration at the collar region, which finally girdles the stem to about 3 to 6 cm and their leaves become dull in appearance. Gradually the lesion turns black, the plant dies within a week and its peeled tissues become studded with numerous black sclerotial bodies. If the infection occurs in the later stage of the crop, the plant shows initial paling and drying of leaves and root rot. The most common symptom in the field is sudden wilting of plants usually after flowering. Black sclerotial bodies can be seen in the root portion where pycnidia bodies can be seen. Fungus: Macrophomina phaseolina (Sclerotial stage. Rhizoctonia bataticola). The fungus produces a large number of black, round to irregular sclerotia. Pycnidia are dark brown to black with an ostiole and contain numerous single celled, thin walled, hyaline and elliptical pycnidiospores. Questions to be answered 1. Pathogen responsible for bluish grey discolouration of groundnut kernel is ______ 2. Shredding of bark is common in ________________ disease 3. Pycnidial stage of Rhizoctonia bataticola is _________________ 4. TSWV infects ______________ and ___________ crops 5. Two types of conidia produced by Fusarium wilt pathogen are ______ and ______ 6. Spots with concentric rings are the characteristic symptoms of _________ True or False 1. Bud necrosis is transmitted by whitefly, Bemisia tabaci 2. Insect damge to sunflower heads predisposes head rot infection Differentiate 1. Crown rot and Stem and pod rot of groundnut 2. Root rot and Stem and pod rot of groundnut 3. Early leaf spot and Late leaf spot of groundnut 4. Rust of groundnut and Sunflower 5. Cercospora leaf spot and Alternaria leaf spot of castor Ex. No. 5 DISEASES OF COTTON AND Date: SUGARCANE COTTON 1. Seedling Blight Symptoms: The symptoms include pre-germination decay of seed (pre-emergence damping off), decay of seedling (post-emergence damping-off), and partial or complete girdling of the emerged seedlings at or near the soil surface and seedling root rot. Fungi: Pythium sp., Fusarium moniliforme, F.oxysporum, F. roseum, Rhizoctonia solani (Thanatephorus cucumeris) and Macrophomina phaseolina. 2. Fusarium wilt Symptoms: The earliest symptom appears on the seedlings in the cotyledons, which become yellow and then brown. The base of petiole shows brown central ring followed by wilting and drying of the seedling. In adult plants, the first symptom is yellowing of margins of leaves and area around the veins i.e. discolouration starts from the margin and spread towards the midrib. The leaves lose their turgidity, gradually turn brown and droop. Symptoms start from the older leaves at the base, followed by the younger one towards the top, finally involving the branches and the whole plant or wilting may be complete leaving the stem alone standing in the field. Sometimes partial wilting on a branch occurs. Blackening or browning of vascular tissues is the other important symptom. Black streaks or stripes may be seen extending upwards to the branches and downwards to lateral roots. In a transverse section of a diseased branch, discoloured ring is seen in the woody tissues of stem. Fungus: Fusarium oxysporum f.sp. vasinfectum. Mycelium is septate. Microconidia are unicellular or bicellular, ellipsoidal and borne on lateral phialides or on phialides produced from short lateral conidiophores. Macroconidia are fusiform (falcate), curved inwards at both end, pedicellate and 4-5 septate. Chlamydospores are terminal and intercalary, single or in chains, hyaline and smooth to rough walled. 1 Verticillium wilt b. Sclerotia are minute. Later. girdling of stem and death of the seedlings result in gappiness in the field. Resting mycelium dark-brown to black. black and smooth. . branched and the branches arise almost at right angle. Infected stem and roots. Conidiophores are abundant. cup inwards. the lesions appear as light green or yellow green specks. On the upper surface. oblong or elliptical. smaller bolls. leaving bare branches. oval or cylindrical. Grey mildew Symptoms: Initially the lesions are irregular. 5. Hyphae are colourless. elliptical to irregularly subcylindrical. On the upper surface also. Phialides sometimes secondarily branched. Browning may taper off into longitudinal streaks in the upper parts and branches. A large number of dark brown or black sclerotia are seen within the bark and disintegrated cortical tissues of the roots. Root rot Symptoms: The fungus causes two types of symptom. Dark brown resting mycelia are formed only in association with microsclerotia. when split open. Seedling death: Appearance of black lesions on the hypocotyl. white to grey powdery growth appears.Symptoms: Affected plants show a characteristic chlorosis of leaves and stunting. The affected leaves fall off. Early and severe defoliation leads to premature boll opening and immature poor quality lint. Eventually the entire leaf surface is covered by white to grey powdery growth. Conidia arise singly at apices of phialides. With the formation of profuse conidiophores and conidia. Pulled out plants reveal the rotting of entire root system. bounded by veinlets). Mycelium floccose and white to greyish. hyaline. verticillately branched. translucent and angular in appearance on under surface of leaves. Lesions occur on the bracts subtending the bolls. 3 to 4 mm wide. They may be globose. pale. Fungus: Macrophomina phaseolina (Sclerotial stage: Rhizoctonia bataticola). Fungus: Verticillium dahliae. Pycnidia are ostiolate and the wall is thin. which have immature lint. The veins turn brown and interveinal areas become chlorotic. will reveal dark brown discolouration of the woody stem and root. Affected plants bare few. 4. hyaline and single celled. frosty white to grey mildew patches (spots) appear on the under surface. All the leaves from top to bottom droop down and are killed with in a day or two. The affected plants can be easily pulled out. the affected leaves dry up from the margins. turn yellowish brown and fall off prematurely. The lesions are restricted to leaf areolae (small areas. which are the characteristic feature of this disease. Root rot: The most prominent symptom is sudden and complete wilting of plants. hyaline. Pycnidiospores are one celled. 3 to 4 phialides arising at each node. They are a. Cupping of the lamina follows this stage and the tissues between the veins dry in patches between the veins producing ‘tiger stripe effect’. erect. The bolls develop lesions resembling to those on the leaves. Ramularia areola. Mycelium is white or rosy buff or yellow. often slightly constricted at septa. erect. Alternaria blight Symptoms: On the leaves dull brown. With the advancement of the disease. branched below and then into 2 to 3 branches bearing phialides. hyaline to olivaceous. Conidiophores are single or in groups. closely compacted to form a subhymenial layer. Sporodochia are of pin head size and dark green or greenish black in colour. obclavate or with the body of the conidium ellipsoidal tapering abruptly to a very narrow beak which is equal in length to or up to twice as long as the body. smooth. The lesions on bracts are broader with a narrow reddish violet margin. Conidia are solitary or sometimes in twos. Leaves exhibit irregular holes or shot holes. the spots increase in the size and coalesce together involving more leaf area. The ascospores are hyaline. Conidia are borne singly or in chains and are hyaline. round or circular spots are seen. Perithecia contain many asci. Severely infected plants show defoliation. The leaves affected in the margin exhibit holes resembling that of ash weevil damage. Conidiophores are hyaline.Fungus: Septocylindrium gossypii (Syn. hyaline closely compacted into parallel rows forming a dense hymenial layer. irregularly oblong with pointed ends. Under severe conditions. Phialides in whorls of 2 to 5 at the apex of conidiophore branches. mostly cylindrical rarely slightly clavate. reddish-brown. hyaline and branched at the base. straight or curved. longipedicellata). Fungus: Alternaria macrospora (Syn: A. S. pale-to mid-brown. Spores (conidia) are rod-shaped with rounded ends. almost cylindrical or tapering slightly towards the apex. cylindrical. Cankers developing on the stem leads to cracking and breaking of the stem. with 4 to 8 transverse and several longitudinal or oblique septa. 6. Fungus: Myrothecium roridum. areola. Cercospora leaf spot . smooth walled. Mycelium is dark and septate. In severe cases spotting on the stem causes breaking. minutely verruculose. black. 7. with one to several conidial scars. simple straight or flexuous. 8. in mass and guttulate. One or two concentric rings of sporodochia can be seen on the spots. Conidiophores are short. two celled and angular. septate. Myrothecium blight Symptoms: Light brown to tan coloured with violet to reddish brown margins are seen on the leaves. Older spots may coalesce and produce large and irregular dead areas with concentric rings. Perfect stage: Mycosphaerella areola). the lint gets stained yellow to light brown. unicellular or 1-3 septate. Mycelium is endophytic and septate. Severe infestation leads to defoliation. desmium). In later stages. The infected bolls cease to grow. Masses of conidia appear as dusty shading on the upper and lower surfaces to dead tissue in the old spots. Conidia are hyaline. their centres become black. The wood becomes brown. resulting in wilting of the seedlings.Symptoms: The spots are round or irregular. pale golden brown. purplish brown spots and they coalesce to form larger patches. hyaline to greenish. irregularly arranged. one celled with one germ pore and the wall is pigmented. two celled often unequal and narrowed at the septum. 9. Ascospores are light. cylindrical and 4 to 7 septate. Perithecia are ovate. Small water-soaked. Sometimes the lesions may extend down to the roots. Tropical rust Symptoms: Epiphyllous uredia are formed in small. ostiole protrudes out of either surface. wither and defoliate. In older spots the centre may crack and break away and leave a ragged margin. curved. The infection may spread to the entire leaf. slightly depressed spots are seen on the bolls. and narrow towards the tip and rounded at the base and 5 to 7 septate. In matured seedlings the fungus attacks the stem leading to stem splitting and shredding of bark. black partly immersed in the leaf tissues. one-septate. fusoid. Fungus: Cercospora gossypina (Perfect stage: Mycosphaerella gossypina). The disease attacks bracts. rust pustules can be seen on the bolls also. The lint is stained yellow or brown becomes a solid brittle mass of fibre. Fungus: Phakopsora gossypii (Syn: P. 10. Conidiophores emerge through stomata in fasicles. poorly developed and usually do not germinate. long. yellowish brown with purple. Severely affected leaves become paler. flexuous. Teliospores are sessile but not echinulated. Mycelium is septate and intercellular. dark brown or black border and white centres. Uredospores are echinulated and borne singly. elliptical or broadly. septate. rapidly enlarge and extend to the bolls. dark brown. slender. light cinnamon-brown dots. Such affected seedling wilts and dies. Uredia are oval and corky at first and later at maturity become circular. light yellow. burst and dry up prematurely. Telia are subepidermal but not erumpent and appear as powdery. irregularly bent near the tip. reddish brown. As the lesions grow in size. Badly affected seeds are light brown. oval or broadly with short spines. Later the spots coalesce with each other. Uredia are subepidermal and erumpent. The lesions on the collar region are elongated and reddish brown in colour. circular. . Anthracnose Symptoms: The fungus infects the seedlings and produces small reddish or light coloured circular spots on the cotyledons and primary leaves. They are dark. 11. Ascospores are hyaline. Seedling blight: The first evidence of the disease is seen on cotyledons. Nematospora nagpuri and Botryodiplodia sp. circular or irregular spots and spreads gradually resulting in the distortion of the cotyledons. The bolls never burst open and fall of prematurely. septate and pointed. They are straight or slightly curved. single celled and cylindrical. Aspergillus flavus. Colletotrichum capsici. nearly oblong with rounded ends. water-soaked areas develop on the lower surface of the leaves. capsici: In the acervuli setae are long. . dark green. C. Setae are long and dark brown below and colourless at the apex and straight or flexuous.niger. Fungi: Fusarium moniliforme. unicellular. cause rotting of the pericarp leaving the internal tissues free. straight and about twice the length of conidia. resulting in death of the seedlings. a. They are spherical or pear-shaped sometimes with a prominent beak. bacterial ooze is formed as crusts.Fungi: Colletotrichum capsici and Glomerella gossypii. thickwalled and pale at the ends. The affected leaves crinkle and twist inward and show withering. intercellular. The bacterium moves to the stem of the seedling through the petiole and invades the terminal region. c. the rotting may be external. which lead to defoliation. base narrowed and not falcate. a large number of fruiting bodies of fungi concerned are observed. giving a typical blight appearance. Asci are numerous. Conidia are unicellular. Angular leaf spot: Small. In some cases. cylindrical. Conidiophores are hyaline. Vein blight or vein necrosis or black vein: The infection of veins causes blackening of the veins and veinlets. nonseptate or 1 to 2 septate. Hyphae are immersed in the tissues. 12. Bacterial blight Symptoms: The bacterium produces the following five types of symptoms. On the affected bolls. extending through the epidermis. elliptical or slightly curved. Infection spreads to the inner tissues and rotting of seeds and lint occurs. slender. The infection spreads from veins to petiole and cause blights. The spots are restricted by veinlets and become angular. A. b. Rhizopus nigricans. On the lower surface of the leaf. It appears on the cotyledons as small water soaked. enlarge gradually and when the leaves become older they turn to reddish brown colour and infection spreads to veins and veinlets. Conidiophores are hyaline. dark brown. Boll rot Symptoms: The disease appears as small brown or black dots which later enlarge to cover the entire bolls. Glomerella gossypii: The anamorph is Colletotrichum gossypii. and falcate and smooth walled. There are no white transverse bands as in red rot. The boll lesions gradually enlarge. Radicle and plumule are attacked and show complete rotting in the soil. germinating seeds or young seedlings are killed before they reach the soil surface. which may girdle the stem and branches to cause premature dropping off of leaves. The leaves dry up. It is not acid fast. The roots show reddish brown discolouration. e. 2. cracking of stem and gummosis resulting in breaking of the stem and hang typically as dry black twig to give a characteristic ‘black arm’ symptom. Brown patches on the rind are formed and underlying tissues die. malvacearum. P. the lint quality becomes poor. dark brown to black lesions are formed. It is a facultative aerobe. The midribs of all leaves in a crown turn yellow while the leaf lamina remains green.arrhenomanes and graminicola. when tissues in the lowest internodes show a brick red colour with reddish individual vascular strands. The canes become light in weight and hollow. The pathogen ramifies in the reddened pith making it to become hollow. Black arm: On the stem and fruiting branches. SUGARCANE 1. It is non-spore former and capsulated. In post emergence. yellowing of crown leaves. The infected area appears as small. P. At this stage.d. dark green water-soaked area. The seeds in the bolls are reduced in size and their viability is lost. the seedlings are attacked near the ground level soon after their emergence from the soil. saprophytic organisms may attack the bolls. Gramnegative and motile by a single polar flagellum.ultimum. In severe cases . turn black and become sunken as the tissue dies. Infected stem tissues become soft and water-soaked and the affected seedlings topple down. P.damping off. Boll rot: Basal infection of flower buds and young bolls cause them to fall off prematurely. It is rod-shaped. The canes may wither in groups. They are slightly raised and round in outline in contrast to the angular lesions on leaves. Bacterium: Xanthomonas campestris pv. Fungi: Pythium aphanidermatum. thus causing boll rot and gummosis. Damping off Symptoms: In pre-emergence damping off. The infected bolls fail to open and if they open. Wilt Symptoms: The earliest symptom of the disease is stunting. light brown. ovoid or oblong. The presence of these cross-wise white patches is considered as a diagnostic character of the disease. Fungus: Ceratostomella paradoxa (Syn: Ceratocystis paradoxa. 3. two kinds of spores viz. The conidia are hyaline. The mycelium is hyaline or light brown. Typical symptoms of red rot are observed in the internodes of the stalk by splitting it longitudinally. Often the infected leaves may break at the lesions and hang down with large number of minute black dots.. 1-celled and smooth. Perithecia are immersed. The lesion is initially blood red with dark margins and later on with straw coloured centres. Later the whole crown may wither away in eight to twelve days. Ascospores are ellipsoid with unequally curved sides. simple or vertically branched. In the imperfect stage. Fluffy growth of the fungus with conidia covers the cavity. The setts may decay before the buds germinate or the shoots may die back after reaching a height of 15 to 30 cm. Red rot Symptoms: The third or fourth leaf withers away at the tip and along the margins.spindle shaped cavities tapering towards the nodes develop in each internode. These spores are produced endogenously and are pushed out of the conidiophores in long chains. arise laterally from hyphae and are hyaline to pale. globose and ornamented with numerous septate coralloid appendages. Pine apple disease / Sett rot Symptoms: The fungus enters through cut ends of the setts and spreads rapidly through parenchymatous tissues. leaves become chlorotic and frequently the diseased plants die. Conidiophores are slender. The black colour is due to presence of large number of macroconidia which are dark coloured. The conidiophores are septate tapering towards the apex. . produced in chains or in single. septate. 4. Thielaviopsis paradoxa). Conidiophores are thick walled and brown. The leaves of the affected stalks may wilt and badly affected shoots become stunted. These include the reddening of internal tissues with white spots which are usually elongated at right angles to the long axis of the stalk. The affected tissues first become reddened but remain firm for sometime. thin walled and hyaline at first and become brown later. ellipsoid without septation. Fungus: Cephalosporium sacchari. Mycelium is white and sparsely septate. And the macrospores (macroconidia) are larger. Affected setts when split longitudinally (in early stage of the disease) will emit an odour resembling that of fresh pine apple fruit. Ophiostoma paradoxa. microspores (microconidia) are rectangular to slightly oval. Then the core in the internode becomes hollow and black in colour. Minute red spots also appear in the centre of the mid-rib and develop both direction forming small or long lesions. Conidia are falcate. Perithecia are immersed. The mycelium is intercellular and collects as a dense mass between the vascular bundles of host cell and produces many tiny black spores. meanwhile gaining a light but definite but narrow pale yellow green halo. branched at the base. brown. As the disease progresses. Uredia occur on leaf sheath also and the entire . Initially it is white but later becomes black and dusty. Uredia are confined mainly to the lower leaf surface. Setae are simple. Conidiophores are hyaline to brown. hyaline and one-celled. 5. smooth. mainly in length and turn brown to orange brown in colour. Asci are clavate. including the tillers are infected with smut. thin membrane (host epidermis). slightly swollen at the base and tapered towards the apex. formed from the upper cells of the acervulus. These sori increase in size. straight or slightly curved and ellipsoid or ovoid. unitunicate and 8-spored. single or aggregated often in short lines between vascular bundles. The whip-like structure is few centimeters to several centimeters in length and sometimes coiled or curved back on itself.Fungus: Colletotrichum falcatum (Syn: Physalospora tucumanensis). Sporidia are single celled. Smut spores are spherical. 6. Fungus: Ustilago scitaminea. dark brown to black and ostiolate. Smut / Whip smut Symptoms: Affected plants are stunted and it is characterized by the production of a long whip-like structure from the terminal bud of the stalk. Ascospores are one-celled. the membrane rupture exposing millions of minute. covered by a white. hyaline. black smut spores (teliospores or chlamydospores). Sporidia may multiply by budding. septate. The uredia are subepidermal and rupture the epidermis under pressure to release the dense masses of orange coloured uredospores. globose. Smut sori are occasionally seen on leaves and stem. Rust Symptoms: The sori are minute. light brown and germinate to produce 3-4 celled hyaline promycelium and produce 3-4 sporidia. non-septate or septate. smooth. thin silvery membrane. On the outside there is a white. septate. elongated. Acervuli are round to elongate. hyaline and oval with pointed ends. These plants tiller excessively and all plants in a stool thus formed. The smutted clumps also produce mummified arrows in which lower portion consisted of a normal inflorescence with typical flowers and the upper portion of the rachis is converted into a typical smut whip. simple and filiform. yellowish which are visible on both the leaf surfaces. Paraphyses are numerous. The leaves are usually small and are formed closer and sometimes scale-like buds are present on the lower nodes. Mycelium is intercellular. Ring spot Symptoms: On the leaf blades the spots are dark green to brownish but later become reddish brown. septate and thin. Fungus: Leptosphaeria sacchari. two celled. Fungus: Drechslera sacchari (Syn. In P. Teleutospores are pale yellow. elongated and blackish. Teleutosori are small. mid-pale to midgolden. The spores are borne on very short stalks. kuehnii. elongate in the direction of the main axis of the leaf. The fungus produces a toxin called helminthosporin. Later in the season. rounded or somewhat flattened above. each usually surrounded by a narrow yellowish zone. with a reddish brown centre and a light coloured border or halo. with . Finally. club shaped to cylindrical and are on the margins of the sori. The typical spot is oval in shape and slightly less in width. Small. dark green than the normal leaf. and spiny and are with four equatorial or scattered large distinct germ pores. club shaped with a constriction at the septum.foliage looks brownish from a distance. black. Sometimes an outer yellowish zone persists. paler towards the apex. At first the spots are irregular in shape. Conidia are slightly curved or occasionally straight. Within 3 to 4 days. especially near the ends of the spots. more or less diamond shaped or oval. P. dark-brown or olivaceous brown. the uredospores are orange to orange brown. oblong to club shaped. thick-walled. narrow below. melanocephala. The spot increases in size. smooth and 5 to 9 pseudoseptate. erianthi) and P. Similar spots occur on the leaf sheaths also. the centre of the spot becomes straw coloured. Later the central portion of the spot becomes reddish brown.brown. The old spot typically has the straw coloured centre surrounded by a narrow reddish zone. kuehnii (Uromyces kuehnii). They are pale to brick red and are borne on short stalks. Eye-spot Symptoms: The lesion appears as small watery area. the centre breaks down and becomes greyish and the hollow becomes less prominent. uredospores are with 3 to 5 equatorially placed germ pores. Teleutospores are two-celled. dark brown to black telia appear on the lower surface of the leaves. Perithecia are at first subepidermal or erumpent. blackish specks appear on the old spots. As it becomes older. Helminthosporium sacchari). smooth walled. slightly constricted at the septum. straight or flexuous. In P. They are pale to dark. spherical or subglobose. oval to pear shaped. Conidiophores arise singly or in small fascicles. 7. Fungi: Puccinia melanocephala (Syn. lesion becomes more or less straw coloured. cylindrical or narrowly ellipsoid. 8. indosacchari. pale to yellowish areas on the leaves. The virus is rod-shaped.D.B.E and F. especially in the ratoon crops are severely stunted. On the stalks dark – coloured stripes. In matured canes the nodes show discolouration of vascular bundles.a papillate ostiole.C. Affected plants are stunted and chlorotic. Tillering of the canes is less. approximately 2 rowed. The diagnostic symptoms of mosaic are slow growth. oblong. Ordinarily these are elongated into more or less irregular stripes or streaks surrounded by areas with the normal green colour. 3-septate. constricted at the septa. 10. Yield is considerably reduced. Causal agent: Sugarcane mosaic virus (SCMV). indefinite. The disease is present in plant crops also. Grassy shoot disease (GSD) . In India six strains have been identified viz. delayed and the growth of the plant is very slow. xyli. In some cases rind tissues collapse and the stalks appear dry.. In young growing shoots the growing point both nodes and internodes are pinkish in colour. while in the mature stalks of most varieties the lower portion of the node is usually orange to light red or yellow.. Melanaphis sacchari and M. The fibrovascular bundles in this discoloured band are apparently clogged. Paraphyses are filamentous. occur with some varieties. Eight spores per ascus. Ratoon stunting disease (RSD) Symptoms: Growth is retarded and often the affected plants. Chlorotic areas frequently are also present on the leaf sheaths. 11. Mosaic Symptoms: The characteristic symptom of mosaic is the presence of chlorotic or light coloured areas on the leaves. reddish. hyaline or sub-hyaline. the conditions of growth the temperature and the strain of the virus involved. Internodal length is much reduced. purplish or brownish or on the dark coloured canes light – coloured stripes. Strain ‘B’ is the most common which produces mild mottle of the leaves. Causal agent: Clavibacter xyli subsp. Girth of the canes is not usually affected. slightly narrowed at the base. about the same length the asci and are hyaline. Germination of sett is low. It is transmitted by the aphids viz. Rhopalosiphum maidis. 9. A. Asci are cylindrical. The chlorotic areas are more distinct on the actively growing basal portion of the leaf. general yellowing of the foliage and the presence of irregular. The mosaic pattern resulting from the different shades of green varies with the cane variety. It is ovoid. It is found in the sieve tubes of phloem in the affected canes. It is sett-borne and transmitted by hopper. Red rot of sugarcane primarily spread through diseased setts Differentiate 1. Sett rot and red rot of sugarcane 4.. Premature and excessive tillering gives a crowded ‘grass – like’ appearance to the clump. In some cases there is also formation of aerial roots at the lower nodes. Causal agent: Phytoplasma. Toxin produced by Helminthosporium sacchari is _____________ 2. Aphis sacchari and A. Shoots growing from diseased setts remain dwarfed or stunted. Alternaria blilght and Myrothecium blight of cotton 3. with or without albinism (white leaf). Canes are thin with shorter internodes. Diseased plants exhibit leaves which are light green or white. weak and small millable canes are produced in a clump having primary infection and these do not produce inflorescence or arrow. Questions to be answered 1. spherical and irregularly shaped. In Sugarcane. Proutista moesta and aphids viz. The buds on such canes are usually papery and abnormally elongated. The motile spores produced by damping off pathogen is ___________ 3. malvacearum is a seed-borne pathogen 2. Affected clumps are stunted and exhibit premature proliferation of axillary buds. Black powdery mass released from whip smut of sugarcane are _____________ of the pathogen 4. Xanthomonas axonopodis pv. The root system gets considerably reduced. It moves from cell to cell through pores in the sieve plate. Fusarium wilt and Verticillium wilt of cotton 2. black whip-like structure is formed from __________ of the plant True or False 1. Rhopalosiphum maydis. indosacchari. Hardly one or two thin.Symptoms: The disease is characterized by the production of numerous lanky tillers with small and narrow leaves. Red rot and wilt of sugarcane . Leaves lose green colour and dry up. Powdery mildew Symptoms: Whitish bloom of powdery mildew is seen on upper surface of leaf. BANANA. . Affected fruits do not develop in size and may drop before attaining pea size. Whitish patches formed on the stalks of inflorescence which later turn black.5. White coating is due to the thick covering of mycelium. conidia and conidiophores. Grassy shoot disease and Ratoon stunting disease of sugarcane Ex. 6 Date: DISEASES OF MANGO. No. GUAVA AND SAPOTA MANGO 1. blossoms and fruits are attacked. Latent infection is carried out from the field and develops further in storage. round lesions on fruits enlarge rapidly and cause rotting particularly in storage. 2. turn brown to black and are surrounded by a distinct halo. Leaf tip dries up and the infection spreads down towards petioles. Photosynthetic activity and yield are reduced. fruits and tender stems. Conidia single celled. which causes rotting of fruits in store houses. Because of the production of masses of black spores. Affected portion dries and falls off exhibiting “shot hole”. may fall out. 3. Sooty mould Symptoms: The disease is associated with scale insects and aphids. dry up. The spots are light brown with a dark brown margin. Fungi : Capnodium ramosum. Affected areas usually crack and sink slightly. dry and show “die-back”. the foliage appears black and ugly and hence the name sooty mould. petioles. Conidia are five celled. C. Pestalotia mangiferae). Small water soaked lesions appear in groups towards the tip of the leaf. Appendages are slender. Skin becomes thin and pulp is rotten. barrelshaped and are produced in chains. Fungus: Pestalotiopsis mangiferae (Syn. They increase in size. 3-5 in number and are seen at the apex of the conidia. Bacterial leaf spot (Black spot) and canker Symptoms: It attacks leaves. Black round spots are of more than 5 mm seen on matured fruits. Young leaves wither and dry up. which stick to the leaf surface due to the sticky honey dew. conidia hyaline. single celled. hyaline. Sometimes leaf margins darken. conidiophores non-septate short and hyaline. Middle three cells are coloured and the end cells are hyaline. On young fruits. The honey secreted by the insects on the leaves and twigs of host plants attracts the fungus which multiplies rapidly. spreading on the plant surface. Mycelium is coloured and septate. 4. Mycelium is ectophytic.mangiferae and Meliola mangiferae. giving the leaf a ragged appearance. 5. Young branches wither.Fungus: Oidium mangiferae (Acrosporium mangiferae). stems. round or elongated and seen at the distal end or any part of leaf. On leaves the spots are round to irregular and dark brown. Grey blight Symptoms: Spots on leaves are small. Anthracnose Symptoms : Leaves. lesions are water soaked and they turn . Fungus: Colletotrichum gloeosporioides. Water soaked. Acervuli are seen as minute black dots on affected portions. Cankerous lesions appear on petioles and branches. falcate and are produced in acervuli. Mycelium is septate and coloured. Elliptical lesions on stem girdle the stem. Yellowing extends upwards and finally heart leaf alone remain green. 3-septate and they are tapering at both the ends. At the point of attachment haustoria penetrate and absorb food material and cause cessation of growth of affected branches. spherical to oval and hyaline to slightly yellow in colour. stalk and buds are affected. The parasite also attacks Citrus spp. mangiferae-indicae. D. Fruits are shriveled. Acervuli are round or elongated and erumpent. smooth and glistening. Microconidia are single celled or rarely one-septate. Trees gradually deteriorate and die. Parasite: Giant mistletoes.ampullaceus. Leaves break near the base and hang around the pseudostem. Colonies on PDA are white to creamy white. circular. Fungus: Fusarium oxysporum f. Macroconidia are sickle-shaped. capillatus and D. thick. 6. Infected fruits exhibit cracks on the skin.Giant mistletoe Symptoms: The parasite’s stem creeps along the stem of mango and it attacks by peg-like growths at several places. Badly affected fruits drop Bacterium: Xanthomonas campestris pv. This causes discoloration and rotting of the pulp. macroconidia and chlamydospores. They turn black and are covered with pink mass of fungal spores. jack. Branch becomes black. D. rod-shaped. BANANA 1. Fungus: Gloeosporium musarum (Colletotrichum musae). Anthracnose / Fruit rot Symptoms: Fruits are affected when immature. The bacterium is Gram negative..sp. Affected branches lose the foliage and dry up. cubense. Phanerogamic parasite. Entire fruit. leathery and green.Dendrophthoe longiflorus. Conidiophores are . It forms a bushy growth. Chlamydospores are thick walled. motile by means of a polar flagellum and is without endospores. Panama disease / Fusarium wilt Symptoms: Yellowing of lower most leaves. Longitudinal splitting at the base of the pseudostem is seen. hyaline and branched. Leaves of the parasites are narrow. Fungus produces microconidia. hyaline. 2. neem. etc. Mycelium is septate and coloured.elasticus. Central portion of the affected rhizome is dark brown and purplish streaks radiating from the centre are seen in the cross section.black. Fruits are fleshy with sticky mucilaginous contents. Mycelium is septate. hyaline and elliptical or oval. prematurely. Fungus: Phyllostictina musarum (Syn. Pycnidiospores are needle-shaped. When the pseudostem is cut greyish brown bacterial ooze is seen. cylindrical. Conidia are brown. Individual fingers of the bunch turn yellow. In some fruits. 6. become irregular and are with a bright yellow band. raised spots are seen on the leaves. Black tip (Black spot) Symptoms: Three types of symptoms viz. The spots increase in size and show grey centre and brown margin. Conidia are single celled. Whole plant dies. Discolouration is in the central portion. Helminthosporium torulosum) Mycelium is septate. Tips of fruits are black. Leaves turn dingy yellow or whitish yellow. Freckle disease / Black spot Symptoms: Numerous. Sigatoka leaf spot Symptoms: Elongated dark brown spots appear on leaves. Fructification of the fungus is seen as black dots in the grey centre. minute. hyaline and multiseptate. fruit tip discolouration or black tip and fruit spot are caused by the same pathogen. hyaline and septate. Conidia are hyaline. Fungus: Cercospora musae (Syn. Fungus: Deightoniella torulosa.cylindrical. Leaves become yellow. Characteristic discolouration of the vascular strands from pale yellow to dark brown or bluish dark appears. black. distorted and fruit pulp turns dark-brown. Petiole breaks at junction with pseudostem. hyaline. small and elongated. Macrophoma musae). The fungus produces pycnidia and pycnidiospores. Bacterial wilt / Moko disease Symptoms: Plants show rapid wilting and collapse of the leaves and premature ripening of the fruit. Syn. Each spot is surrounded by a yellow halo. long and 3-5 septate. Black spots appear on the main veins of the lamina in proximity to the leaf margin. Mycosphaerella musicola). 5. 7. Bacterium: Burkholderia solanacearum (Pseudomonas bacterium is Gram negative and rod-shaped. Spots are more on the upper surface.. 4. The spots increase in size. Spots on fruits are superficial (skin deep) and are produced either singly or in groups. tapered towards the apex. Bacterial Leaf spot solanacearum). 5-7 celled. Mycelium is septate and coloured. round spots with reddish brown or black centre and a darker green water-soaked halo may be seen. The . branched and brown. thick walled. black spot on the leaf surface. broader at the base and taper towards top. More spots on leaves cause drying. Suckers become black. 3. 11. which leads to drying of leaves. narrow. The bacterium is a Gram negative rod with a polar flagellum. Leaves are shortened. rigid and brittle with broken green bands on the petioles. Banana Streak Symptoms: The disease is characterized by the presence of discontinuous yellow streaks along the blade or midrib which turn into discoloured patches. Upwards curling of leaves. Vectors are Aphis gossypii and A. partial unfurling of lamina. Diseased plants do not reach maturity. necrosis of leaf sheath and occasional heart leaf rot also occur. It is transmitted through planting materials and by aphids. Vector : Pentalonia nigronervosa (aphid) 9. Necrosis appears on the lower side of the sheath. Leaves are Causal agent: Banana Bunchy top virus (BBTV) or Musa virus-1. musicola. Causal agent: Banana Bract Mosaic Virus (BBMV). breaking of leaf tip. Causal agent: A strain of Cucumber mosaic virus. They turn dark brown and finally black with a chlorotic halo. Banana Bract mosaic Symptoms: The disease is characterized by appearance of black streak on petiole. Suckers exhibit reddish brown streaks at emergence. Clustering of leaves at crown with a “traveler’s palm” appearance elongated peduncle and half filled hands are its characteristic symptoms. Bacterium: Xanthomonas campestris pv. Leaves roll downwards. light green or yellowish green mottling and distortion of young leaves and dwarfed growth are the characteristics symptoms. .Symptoms: Brownish liner streaks appear along the veins. Bunchy top Symptoms: Plants are extremely stunted.maydis 10. 8. yellow or pinkish colouration on pseudostem and mosaic-like purple spindle shaped streaks on the bract. Eruption of veins on the leaves. non-capsulated and non-spore forming. Banana mosaic / Infectious chlorosis Symptoms: Chlorotic or yellow green islands are seen on the leaves. dry up in the affected portions presenting a scorched appearance. Leaves are erect and crowded at the top forming a rosette appearance. Fungus: Gloeosporium psidii (Glomerella psidii). The disease is neither transmitted mechanically nor by aphid vector. hyaline and oblong. Diseased portions are comparatively harder and develop cracks. become hard and are not palatable. branched and septate. Macroconidia are multiseptate. . Infection on fruits is generally on green fruits. Mycelium is septate and dark coloured. circular spots appear on the unripe fully grown fruits and bear numerous. Mycelium is hyaline. Acervuli are seen on the centre. Main branches show dieback symptoms. Trees do not produce any new flush or flowers. Unopened flowers and buds are attacked and are shed. Fruits produced in affected plants are very small. Fungus: Fusarium oxysporum f. oval and hyaline. A. psidii. GUAVA 1. Barks turn light brown. Virus particles are bacilliform. B. 3.Causal agent: Banana Streak Virus (BSV). Acervuli are seen on fruit stalks. Microconidia are unicellular. Anthracnose / Fruit rot Symptoms: Dark brown to black. 2.sp. curling and drying but they do not shed for sometime. Numerous circular. raised dark coloured corky cankerous growth occurs on the unripe fruits. Infected fruits give a chicken pox appearance. Scab disfigures the fruit and reduces market value. It is severe at the time of fruit bearing stage. minute. Trees die within a year. They do not ripe properly. Chlamydospores are intercalary /terminal. Grey blight and fruit canker /Scab Symptoms: On the leaves spots are grey with brown margin. Several spots coalesce to form bigger lesions. Ripe fruits become soft. black stromata in the centre of the lesion. Acervuli are dark brown to black. Necrotic ashy grey lesions occur on leaf tips and margins. Conidia are single celled. Affected branches bearing infected leaves begin to die and the twig barks show severe splitting. hyaline and sickle-shaped. Fusarium wilt Symptoms: Leaves of affected branches show yellowing. sunken. Conidia are fusiform and 5-celled with three apical setulae.longiflora. brown or red. Sooty growth (mycelium. Fruit lesions are small and dark green to black in colour. Apical cell is conical or cylindrical. Red rust (Alga) Symptoms: Dark green. and Capnodium sp. branches and fruits. Fungus: Meliola sp. Pestalotiopsis leaf spot Symptoms: Reddish brown. Fungus: Psetalotiopsis versicolor. circular spots appear on the leaves.Fungus: Psetalotiopsis psidii. Sooty mould Symptoms: Black sooty growth is found on the surface of leaves. SAPOTA 1. Basal cells are obtuse and erect with a small pedicel. Three median cells are dark brown and gradually bulged and the end cells are hyaline. Branches above the point of attack appear sickly or dry. Conidia. Alga: Cephaleuros virescens 7. 4. parasite with dull green leaves with profuse flowering. 6. In the centre of the spot numerous minute. Leaf spot This is a phanerogamic . Later the spots develop greyish centre with dark brown to reddish margin. The spots become faded after release of sporangia. black fruiting bodies (acervuli) are seen. Three apical hyaline setulae are present. conidiophores and conidia) is associated with the infestation of scales and mealy bugs. Giant mistletoe Symptoms: The parasite attacks young branches of trees in neglected gardens. 5. Acervuli are brown to black. rough patches on the upper leaf surface. which are oblong and 5-celled. Causal agent: Dendrophthoe falcata and D. How the powdery mildew of mango spreads? 2. Questions to be answered 1. Leaf spot Symptoms: Spots with grey centre and reddish margin are seen on the leaves. 4. Fungus: Pestalotiopsis versicolor 3. hollow leaves in bunches. Flat limb Symptoms: Branches are typically flat. twisted with thin. Fungus: Phavophleospora indica 2. Which insect is associated with sooty mould on mango? 3. They are either distributed or grouped on the leaf. dark coloured and superficial. Which disease causes the highest damage to mango crop? How? 6. 4. What is latent infection? Give an example. The fruiting body produced by grey blight of mango is __________ 5. Longitudinal splitting of pseudostem is common in __________ disease 8. The mycelium is septate. The spots coalesce and cause premature leaf fall and reduction fruit yield.Symptoms: Small. A post-harvest pathogen in banana is ______________ . Fungus: Botryodiplodia theobromae. yellow. round and pinkish to dark brown spots with centre are seen on leaves. Sooty mould Symptoms: Black sooty growth develops on the upper surface of the leaves which reduces the photosynthetic ability of the trees. Fruiting bodies as minute black dots can be seen on the pods. More spots cause drying of leaves. Fungus: Capnodium sp. The primary spread of Panama disease is by ____________ 7. Fruits formed are small hard and dry. Gummosis Symptoms: Profuse oozing of the gum on the affected bark forming an encrustation on the bark is the main symptom. 7 DISEASES OF Date: CITRUS. fruit drop and rotting of fruits. POMEGRANATE. Mycelium is coenocytic and hyaline. Pentalonia nigronervosa transmits __________ disease 11. Sporangium is round or pear-shaped and contains zoospores which are biflagellate. Moko wilt and Fusarium wilt of banana 2. PAPAYA. Light brown water soaked irregular spots appear on the leaves and rind of fruits. The bark is destroyed all round the trunk. GRAPEVINE. The teleomorph of Colletotrichum gloeosporioides is _____________ 13. Acervuli is a fruiting body produced by ________ and __________ True or False 1. The bark cracks and shreds longitudinally. No. The bark. APPLE AND PEACH CITRUS 1. Droplets of gum trickles down the stem. Leaves turn yellow and pale. Capnodium is a parasitic fungus 2. Banana mosaic and Bract mosaic Ex. 2. The fruiting body of Flat limb pathogen is ________________ 15. Fallen fruits are covered by whitish cottony fungal growth. Write two important characteristic symptoms of Fusarium wilt of banana 12. Affected tree dies in few months. Name the spores produced by Cephaleuros 14. Giant mistletoe is a complete stem parasite Differentiate 1.citrophthora and P.9. Prior to death the tree produces more flowers but dies before the fruits mature. Fungi: Phytophthora palmivora.parasitica. girdling the tree and eventually the tree dies. Anthracnose and die-back / Wither tip . How Sigatoka leaf spot of banana spreads? 10. wood and cambium show discolouration. P. The conidia of Pestolotiopsis mangiferae is three celled 3. Shedding of leaves from lower branches. 5. Mycelium is hyaline. Mycelium is septate. branched and dark coloured. They drop prematurely. Leaves show irregular corky raised reddish or yellowish lesions mostly on the lower surface leading to severe distortion wrinkling and stunting. When the twigs are attacked the bark is thickened and develops cracks leading to the chlorosis of foliage. Ascospores are hyaline and 1 to 3 septate. twigs and fruits. The photosynthetic activity of the leaves is reduced. The lesions are flat or depressed at the centre. Fungus: Capnodium citri. Conidia are produced in chain. Sooty mould Symptoms: The disease develops as sooty black fungal growth on the leaves. Fungus: Elsinoe fawcetti (Conidial stage: Sphaceloma citri). Black dots of acervuli appear on dead twigs. Acervuli contain single celled. Pseudothecia are produced. Red rust ( Algal disease) Symptoms: Reddish brown circular to irregular spots develop on the leaves. 4. On twigs dark corky outgrowths are seen. twigs and fruits of mandarin. Die-back of twigs after young leaves are shed. 3. Fruits attacked when young are mis-shapened show prominent warty projections. septate and external. Leaves become yellow and distorted and shed. Powdery mildew Symptoms: Mandarin is severely attacked. Conidia formed in pink acervuli are hyaline. Drying back gradually progresses downwards (die-back) with the leaves turning yellow. Young fruits are covered by mildew growth. Later the leaves wither and drop off. hyaline and ellipsoid conidia. They are single celled. hyaline and barrel-shaped. Scab / Verucosis Symptoms : Attacks leaves. Fungus: Colletotrichum gloeosporioides (Sexual stage: Glomerella cingulata). 6. defoliation and death of the affected twigs. Whitish powdery growth appears on leaves and young twigs. Reddish spots are seen on fruits. The fungus lives on the honey dew secreted by scale insects.Symptoms: Affected branches begin to wither from the tip downward. Lesions are cream coloured in young fruits and dark olive grey in old fruits. . Lesions on fruit are corky which often break into caked masses. Tender leaves are highly susceptible. oblong and one celled. Fungus: Oidium tingitaninum. The trees look sickly and fruit yield is reduced. causing death of twigs above the point of attack. The spots on the leaves are raised above the surface as circular. Many twigs are upright and produce smaller leaves. Causal agent: Rickettsia. Vector: Diaphorina citri (Citrus psylla). older branches and fruits. Sporangia are single celled.Alga: Cephaleuros virescens. Characteristic pits or depressions on wood (stem pitting) can be clearly seen on the stem after removal of bark. Leaves of acid lime exhibit large number of vein flecks (elongated translucent areas). Leaf blade may be dwarfed and thickened. oval and releases zoospores. The disease attacks all the plant parts viz. Citrus greening Symptoms: Leaves may be completely yellow or yellow with green veins and small green dots. The fruits are worthless as fresh fruits or for processing. brown corky outgrowth with yellow halo.like bacterium (Fastidious vascular bacterium).). Fruits show orange colour on the sides exposed to sunlight whereas the other side remains dull green. 9. Aphis gossypii and Myzus persicae also spread the disease. Die-back symptom is commonly associated. Roots decay.citri (Syn. Toxoptera citricidus (aphid) is the most efficient vector. 8. dark coloured and aborted. straw yellow coloured. sporangiophore and sporangia.citri. trees are stunted and die. Bacterial colonies on nutrient agar are circular. lemon and grape fruits are attacked. On the fruit surface round to irregular. irregular and raised cankers are formed. The bacterium is a Gram negative rod. Fruits are small. multiple bud formation. Causal agent: Citrus tristeza virus. Halo is absent on fruits. Chlorosis is bound on one side by midrib and on the other side by the lateral vein in the form of green-islands. Offspring blooming and die-back.. lopsided and contain curved columella. It produces thallus. On the twigs. thorns. . forms chains and capsules. aborted seeds and drop prematurely. Bacterium: Xanthomonas axonopodis pv. Twigs show short internodes. Fruits are low in soluble solids but high in acid. Tristeza / Quick decline Symptoms: Lime is highly susceptible. Yield is much reduced. It is an algal parasite. coalesce together and reduce market value of fruits. leaves. twigs. Vector: Aphids viz. Xanthomonas campestris pv. Canker Symptoms: Acid lime. 7. It is an obligate Gram negative bacterium.. slightly raised and glistening. Young leaves are upright become leathery and develop prominent veins. raised cankerous spots are seen. twigs die-back. fruits are small. seeds are poorly developed. The spots are few to many. motile by polar flagellum and non-spore former. Dodder (Cuscuta reflexa) also transmits it. cream yellow or orange coloured. by which it draws nutrients from the host. Fungus: Uncinula necator. Bird’s eye spot / Anthracnose Symptoms: Young shoots are more susceptible than leaves. It perpetuates through seeds which fall on the ground and remain viable until favourable season return. Powdery mildew Symptoms: White powdery coating on the upper surface of leaf either in patches or in full. Sporangia are borne on the branches. hyaline. Leaves turn pale and chlorotic. Fungus: Plasmopara viticola. Stem turns dark brown. pink or yellowish flowers in clusters. Affected leaves become yellow then brown and dry and fall prematurely. Malformation and discolouration of affected leaves also seen. It penetrates the host through haustoria. single celled and hyaline. Mycelium is external. septate and hyaline. lemon-shaped. Corresponding lower leaf surface shows white cushiony downy growth. white. They are thin walled. Berries become leathery. Developed berries turn reddish brown and result in softrot. Conidiophores are short and arise from external mycelium. which are devoid of green pigments and which twine around the stem or leaves of the host. Haustoria present. Causal agent: Cuscuta spp. Each spot is surrounded by yellow halo. Tender shoots are dwarfed. Dodder Symptoms: The parasitic dodder is first noticed in the citrus garden as small masses of branched. Floral infection leads to shedding of flowers and young berries. Sexual fruiting bodies called cleistothecia (with several asci) are myceloid and circinoid (coiled at the tip) 2. show cracking. dry and mummified. Downy mildew Symptoms: Leaves show irregular yellowish spots on the upper surface. Mycelium is coenocytic and intercellular. GRAPEVINE 1. Sporangiophores emerge through stomata. thread-like. 3. They branch monopodially and dichotomously at right angles and tips of branches are blunt. barrelshaped and in chain (Oidium type). shrivel. Brown sunken lesions appear on the stem. Conidia are single celled.10. Berries are covered by white growth. Sporangia produce zoospores. The centre of the spot later become grey. Oospores are thick walled. sunken and fall . leafless stems. It produces tiny. shriveling and mis-shapening. Conidia are single celled. Light brown circular spots on the berries. Fungus: Gloeosporium ampelophagum (Elsinoe ampelina). . 4. Rust Symptoms: Numerous. Fungus: Alternaria vitis. Pycnidia are globose and conidia are ellipsoid and hyaline. oval. Asci are globular. The corresponding upper surface shows necrosis. Severe infection leads to mummification and shedding of berries. unbranched and pale brown. The fungus produces acervuli. hyaline and smooth. Spots increase in size and entire berry is discoloured and decay. orange coloured sori are seen on the lower surface of the leaves. On berries spots are sunken with ashy grey centre and dark brown margin resembling bird’s eye. (Syn. echinulated and single celled. cylindrical. single celled and are found in several layers. angular spots appear on leaves and on young shoots. Matured mycelium is brown and septate. 5. Fruiting bodies are seen as minute black dots in concentric rings on the spots. They are transformed into hard. Conidia are with transverse and longitudinal septa. viticola. Black elliptical sunken lesions on young shoots cause girdling and death. Conidiophores are 1 to 2 septate. Ascospores are hyaline and three-septate. Fungus: Guignardia bidwellii. Fungus: Cercospora hyaline and septate. oval or pear-shaped. Black rot Symptoms: Circular red spots with black margin appear on the leaves. black and shriveled mummies. Ascocarps are produced. Brown leaf spot Symptoms: Dark brown. light yellow. Conidia are 7. Fungus: Phakopsora vitis. Defoliation occurs in severe cases. 6. Infection on stalk of bunches and berries result in shedding of bunches and berries respectively. Leaves with many spots are distorted. Leaf blight Symptoms: On the leaves typical brown spots with concentric rings are seen mostly on the margins. Perithecia are globose and asci are clavate with 8-ascospores which are hyaline. Mycosphaerella personata). Attacked leaves dry completely and defoliate. Young shoots dry up. The uredospores are sessile. 2-celled and sub-ovoid. Teliospores are sessile.off giving a shot hole symptom. Beta spores are one celled filiform and curved or straight. 3. globose and ostiolate. Cercospora leaf spot Symptoms: Light brown spots appear on leaves and fruits. Such infected twigs are flattened. dull violet spots on the leaves. hyaline and simple. short and septate. branched and septate. black dots (acervuli). Bacterial blight Symptoms: Spots on leaves are dark brown and are surrounded by prominent water-soaked margins.. alpha and beta spores. Fungus produces two kinds of spores viz. In severe cases the infected fruits crack and become unmarketable. Black pycnidia are found on the spot on the upper surface of the leaf. The infected leaves turn yellow and drop off. Pycnidia are black. Leaf spot and fruit spot Symptoms: The disease is characterized by small. depressed spots are observed. Severely infected leaves are often distorted and malformed and fall off prematurely. Spots coalesce to form large patches. POMEGRANATE 1. Fungus: Colletortichum gloeosporioides. Phomopsis leaf spot Symptoms: Buff-brown spots appear on the margins of leaves or spots are scattered on the leaves. In severe cases the whole plant dies. Conidiophores are short. Conidiophores are olive brown. depressed with raised edge and dry up. Alpha spores are one celled hyaline and oval. The spots are surrounded by a yellow halo. 4. Fungus: Cercospora punicae. unbranched. Diseased portions appear with minute. Fungus: Phomopsis aucubicola. Conidia are pale olive. Black and elliptic spots appear on the twigs. Mycelium is hyaline. 2. On the fruits dark brown. cylindrical and septate. On the stem .C. Young infected leaves dry up prematurely and drop down. Damping off Symptoms: Young seedlings are killed before they come out of soil. Germinated seedlings topple over at any time after emergence. droop and wilt. Anthracnose . punicae. Bacterium: Xanthomonas axonopodis pv. Roots disintegrate and decay. 3. Foot rot / Stem rot Symptoms: Water soaked lesions appear on the bark near the ground level and enlarge. girdle the stem and causes the branches to break. White patches appear on fruits. Fungi: Oidium caricae. Affected tissues turn dark brown or black. Zoospores are kidney-shaped and biflagellate(with whip lash and tinsel). Mycelium is coenocytic and hyaline. Terminal leaves become yellow.brown to black spots appear around the nodes. It a Gram negative. Fruits shrivel and drop. Fungi: Pythium aphanidermatum and Rhizoctonia solani ( Mycelium brown and septate. The spots on the fruits are raised. Haustoria develop in epidermal cells. White powdery growth appears on the leaves. motile with single polar flagellum. 2. Mycelium is hyaline and septate. non-acid fast and aerobic. Sporangia are lobulate. rod-shaped. Sclerotia are round and black). Finally it results in cracking of fruits. oily and brown to black. Powdery mildew Symptoms: It attacks seedlings and matured trees. PAPAYA 1. 4. Fungus: Pythium aphanidermatum. Conidia are hyaline. barrel-shaped and are produced in chain. Stem is girdled at the base. single celled. brown and much branched. The virus is a flexuous rod. Basal portion of the stem and roots exhibit decay. A. The sclerotia are black.( Aphids). Fruits show circular. A. petioles and stems also. Bark of the trees at the basal region splits into shreds and a large number of sclerotial bodies are seen on affected root tissues. black pycnidia are seen on the spots. New leaves formed after infection show yellow mosaic symptom. Leaf lobes are thin and are increased in number and show shoestring symptoms. circular slightly sunken and 1-3 cm in dia.1. Sparse mycelial growth appears on the margins of spots on fruits.gossypii and Macrosiphum sonchi. It attacks leaves. Puckering and malformation of young leaves happen. 7. drooping and later drying. Fungus: Phyllosticta sulata. brittle and falls out leaving a shot hole appearance. hyaline and oval. The central portion becomes thin. 5. Leaf spot Symptoms: The spots are circular or irregular with white centre and yellow brown margin. Severely diseased fruits turned brown and rot. The lesions coalesce. Leaf curl . Mycelium is septate. 6. Fungus: Macrophomina phaseolina. Acervuli are seen in concentric rings on the petioles. Pycnidia conidia which are single celled. Old leaves get defoliated.medicaginis. Aphis malvae. Casual agent: Papaya mosaic virus / Carica virus. spherical or irregular in shape. Minute. Mycelium is septate and dark coloured.Symptoms: The spots on fruits are brown. Fungus: Colletotrichum papayae (Colletotrichum gloeosporioides). papery. Mosaic Symptoms: Typical mosaic symptoms showing chlorosis with dark green blisters are seen on leaves. 8. water soaked lesions with white spots in the centre. Dry root rot Symptoms: Leaves exhibit yellowing. Under humid conditions salmon pink spores are seen as encrustation. Infection on very young fruits results in mummification and deformation. Vector: Myzus persicae. The mycelium in living tissues is located between cuticle and epidermal cell and septate. Leaves become leathery and brittle. 3. The ascus contains 8 ascospores. Veins thicken and turn dark green. The entire surface of the leaf is covered with the growth of the fungus. circular. Appendages are thick walled. necrotic and may be slightly raised. 2. Scab Symptoms: Scattered. Pink disease . Small white greyish patches of fungal growth appear of leaves on both the surfaces. Affected leaves become crinkled and curled. Affected fruits are deformed and reduced in size. Leaves are dwarfed. rough. rigid and dichotomously branched. Fungus: Podosphaera leucotricha. On the fruits. spots are black. Powdery mildew Symptoms: All parts of the tree are affected. Inverted cups are formed due to inward and downward curling of leaves. D. Ascospores are two celled. curled and fall off. Sexual fruiting body is globose cleistothecium containing only one ascus. Fruits become corky over the entire surface and drop prematurely. Affected fruits remain small or deformed. Similar growth is seen on the twigs also. single celled and barrel-shaped. It produces short conidiophore that give rise to 1 to 2 celled conidia. Each conidiophore bears a chain of conidia. Petioles are twisted into zig-zag manner. Affected plants do not flower or bear few fruits in advanced stages.Symptoms: Leaves show severe curling. crinkling and distortion accompanied by vein clearing and reduction of leaf size. Pseudothecia are formed. ovoid. Each pseudothecium contains 50-100 asci and each ascus has 8 ascospores. brown or olive green spots appear on leaves. The conidia are hyaline. Affected leaves become hard and brittle. The haustoria are produced inside the epidermal cells. Defoliation and stunting are common. straight. Fruit buds are blighted and dropped. The unequal size of the two cells gives the species name. Causal agent: Tobacco leaf curl virus. greenish grey or yellow with the upper cell shorter than the lower cell. APPLE 1. Vector: Bemisia tabaci ( White fly). Fungus: Venturia inaequalis. They become grey. harden and develop crack. The mycelium is ectophytic. They are oval and smoke brown. The fungus is of Oidium type. Affected branches die. Infected leaves fall off prematurely. White root rot Symptoms: Five to 20 year old trees are the most susceptible.September. Both the leaves and petioles may curl. Fungus: Chondrostereum purpureum (Stereum purpureum) 6. Lateral roots turn into brown and the fibrous roots are completely destroyed. Then the leaf tissues gradually change to yellow and finally to a reddish purple tint. Presence of yellow band along larger veins on both the sides is common. The heart root turns dark brown. Leaf curl Symptoms: The disease first appears in the early spring when the leaves begin to unfold. Affected flowers and fruits drop prematurely. Fungus: Dematophore necatrix (Rosellinia necatrix). The fungus is not present in foliage. PEACH 1. The leaf blade thickens and puckers along the midrib and curls. White fluffy mycelium in seen on the laetrile spots in advanced stages. Affected leaves die and drop prematurely. The infected trees give a sickly appearance with bronze coloured leaves during August. but its occurrence in the wood causes histopathological changes in the leaves leading for silvery appearance.Symptoms: The trunk and the branches exhibit pink discolouration on the bark. Twigs become pale green to yellow. Cankers on branches appear as blistered areas. Mosaic Symptoms: Leaves exhibit irregular creamy white or yellow spots which may coalesce. stunted and exude gummy material. Veins do not develop properly. 4. Fruit set is poor. Causal agent: Apple mosaic virus. The bark exhibits drying and longitudinal splitting. 5. Silver leaf disease (Silver leaf canker) Symptoms: The leaves of affected plants show silver metallic lustre during early stages of infection. Leaves turn yellow. Fungus: Corticium salmonicolor. Affected leaves show withering. swollen. The reddish velvety surface of the lamina is soon covered with a whitish grey bloom of the fungus on the upper surface. . Outer layer of bark peels off and gives papery bark condition and the tissues underneath become discoloured. Rust Symptoms: Pale yellow spots appear on both on both the leaf surfaces. velvety blotch. young shoots and fruits. pale green areas which gradually turn dark green. the basal cell is sparsely verucose or smooth and is lighter than the apical call. Circular and darkolivaceous lesions appear on fruits. globose with myceloid appendages. the individual spots merge and form a uniform. Cleistothecia are dark brown. dark-olivaceous. On the under surface brown rusty pustules are seen. Asci are naked and are individually. The leaves are small but the . They become narrow and curled. long and narrow lesions are noticed on the midrib. which are globose.spinosae (Syn. Each ascus bears eight uninucleate ascospores. persicae. Fungus: Venturia carpophila 5. They may be scattered and numerous and cover the entire surface of the leaf. On the twigs. Scab / Freckles/ Black spot Symptoms: The disease affects fruits. twigs and leaves. The branches are numerous and the tree looks bushy. Terminal portion of the growing shoot may get covered with a white powdery layer. 3. Fungus: Puccinia pruni. 4. Dark brown. light brown oval lesions are formed which enlarge and turn dark brown. The under surface of the leaves show angular.. When the leaves are severely infected defoliation occurs. The fungus is similar to Erysiphe but Sphaerotheca has only one ascus in each cleistothecium. In severe infection. Later. Fungus: Sphaerotheca pannosa var. round spots develop on fruits and turn them to pink to dark brown. Tranzschelia pruni-spinosase). White. obclavate and echinulate except at the tip. The young leaves are coated on the upper surface with a thick layer of mycelium. Powdery mildew Symptoms: The fungus attacks leaves. olivaceous velvety dots appear on the surface of these lesions. The fruit becomes abnormal in shape and cracks. The uredia are cinnamon brown. A thick or corky layer of cells is produced below surface of the scabbed region. Epicarp of the fruit becomes leathery and hard.Fungus: Taphrina deformans. 2. Mycelium is intercellular and it does not produce ascocarp. Teliospores are chestnut brown. Later the spots become bright yellow. Peach yellows Symptoms: Trees show numerous upright branches growing from the main stem. The sexual spore of Venturia inaequalis is ______________ 8. Scab and Canker in citrus 6. Taphrina deformans caused leaf curl in _______ and __________ True or False 1. Peach yellows is a viral disease Differentiate 1. Citrus greening and bacterial canker in citrus 7. Fruiting body produced by apple scab pathogen is ______________ 7. Mosaic and leaf curl of papaya 9. Most of the leaves show light green to yellow mottling and have irregular margin and clearing of veins. Peach leaf curl is caused by a virus 3. Flowering parasite affecting citrus is ___________ 4. Powdery mildew and Downy mildew of grapevine 2.basal one or two leaves are abnormally long and straight with inrolled margins. Quick decline and gummosis of citrus 5. Bird’s eye spot and black rot of grapevine 3. Foot rot and dry root rot of papaya 8. Naked asci is seen in _____________ 9. Teliospores of Phakopsora is _______ celled 2. Mycelium of Podosphaeria leucotricha is epiphytic 4. symptoms of wilting and die-back appear resulting in the death of the infected tree. Cross protection technique is followed for the control of __________ disease 5. Citrus psylla is a vector of ______________ 6. The diseased trees look bushy with tufts of small yellow leaves. Later. Name one soil-borne disease of citrus 3. Causal agent: Phytoplasma. Questions to be answered 1. Peach leaf curl and peach yellows . Brown leaf spot and leaf blight of grapevine 4. The tree is stunted and internodes are short. The ascospores of Venturia inaequalis is two celled with unequal size 2. parasitica. Fungi: Pythium aphanidermatum. Rhizoctonia solani and Phytophthora nicotianae var. BRINJAL AND BHENDI TOMATO 1. 8 Date: DISEASES OF TOMATO. The affected seedlings become pale and suddenly collapse. The basal cortical region begins to rot resulting in toppling of the seedlings. Dark brown lesions also appear on stem and the affected tissues soon become rotten. Pythium myriotylum. Damping off Symptoms: The disease may attack the seedlings before the emergence of seedlings from the soil or after the emergence of seedlings.Ex. No. . Conidiophores are dark coloured. The leaves are blighted and become dry. Dark olivaceous greasy spots occur on the fruits. with acute apex and truncate to obtuse base. 5. Dead areas appear in leaf tip and margins. filiform. Severe infection causes defoliation during rainy season. Infections spread fast to entire leaf and petiole. Centre of the spots shows minute black fructifications. Fungus: Fusarium oxysporum f. In each conidium 5 to 10 transverse and a few longitudinal septa are present. Conidia are muriform. Late blight Symptoms: Infection occurs on all the above ground plant parts. dark brown sunken spots are found. 2-6 septate. Whitish mildew like growth appear on leaves under humid conditions. 4. 3. Early blight Symptoms: In the affected leaves circular to angular. light brown which become darker with age. single celled or one septate. The spots coalesce and cause drying and defoliation of leaves. dark brown to black spots with concentric rings appear. The fungus produces microconidia. Mycelium is septate. Internal stem portion exhibits vascular browning. produced terminally or intercalarily on older mycelium. 3-5 celled and hyaline. Macroconidia are sickle-shaped. Fusarium wilt Symptoms: Affected plants exhibit yellowing and drooping of lower leaves followed by such symptoms in young leaves. Fruit cracking and . Dark spots are found at the base of the stem near the ground level and the stem is gradually girdled. On the fruit. stem and calyx. Immature fruits are shed. dark coloured and borne singly. Mycelium is septate. lycopersici.sp. macroconidia and chlamydospores. Fungus: Alternaria solani. Water –soaked lesions with faded green patches appear on the leaves. Pycnidiospores are hyaline. beaked. Spots are also found in the stem at the juncture of the side branches which are easily broken by wind. Plants wilt and die in due course. Septoria leaf spot / Defoliation disease Symptoms: Circular spots with whitish grey centre and dark brown margins are seen on the leaves. Pycnidia are globose and honey yellow to brown. branched. Chlamydospores are thick walled. Fungus: Septoria lycopersici. Microconidia are hyaline.2. round resting spores. oval. Zoosporangia are thin walled. hyaline. Chlamydospores are abundant at later stage. But affected fruits shrink and get mummified. Zoospores are biflagellate. Water-soaked lesions are observed on unripe green fruits. papillate and deciduous. When the affected stem is cut bacterial ooze can be seen. yellowing and wilting of foliage leading to collapse of the entire plant. Several spots cause chlorosis in the leaves and defoliation. In severe cases of attack the whole plant dies. oval or pear-shaped with a distinct papilla at the apex. 6. The fungus produces coenocytic. 7. Haustoria are club-shaped. Bacterial canker Symptoms: On the leaves.appearance of white fungal growth on it may be seen resulting in soft rot. parasitica. Fungus: Phytophthora nicotianae var. Sporangia are ovoid. The affected plants collapse and die. Oospores are spherical. Cross section of the stem near the base will show vascular browning. The old fruits rot and drop. Bacterial wilt Symptoms: Stunting. Bacterium: Ralstonia solanacearum. 8. Buck eye rot / Fruit rot Symptoms: Brown. circular spots with concentric rings are seen on immature fruit at the blossom end. . Mycelium is hyaline and coenocytic. Adventitious roots from the stem are noticed. Oospores are aplerotic and thick walled. Fungus: Phytophthora infestans. Black cankerous spots appear on stem and petiole. thick walled and yellowish brown. Lower leaves droop before wilting. They become corky resembling small scabs with irregular margins. hyaline and branched mycelium. the symptom is seen as small translucent water-soaked spots in the beginning but soon enlarge into black greasy or dark-brown spots surrounded by yellow halo. The fruits remain firm unless secondary organisms attack them. It is Gram negative and rod-shaped bacterium occurs in pairs with 1-4 polar flagella. thickened and become slightly yellow. Leaf curl Symptoms: Typical downward curling and crinkling of leaves are seen. Xanthomonas campestris pv. Mosaic Symptoms: Typical mosaic pattern with dark green and light green areas on leaves.Bacterium: Xanthomonas vesicatoria (Syn. Tomato spotted wilt / Bronzy wilt . 10. Older leaves become leathery and brittle. Branching is enhanced to give a rosette appearance. Vector: Orosius argentatus (Leaf hoppers). It is a Gram negative. plant debris. At times leaflets exhibit. puckered and are small. 12. Fern leaf symptoms. Causal agent: Phytoplasma. Diseased plants are stunted due to reduction in internodal length and become partially or completely sterile. Colonies are circular with bright yellowing colour. Fruits are hard and poorly coloured. Necrotic sunken lesions occur on fruits. Small leaflike growth called enation is observed on the midrib on the lower side of leaf. Causal agent: Tobacco leaf curl virus. Pollens are sterile. Axillary shoots give a purple pigmentation. Vector: Bemisia tabaci (Whitefly). Causal agent: Tomato mosaic virus. The virus is transmitted by contacts (sap transmissible). 9. Tomato big bud Symptoms: Top leaves become yellow and with smaller leaflets. Newly emerging leaves exhibit slight yellow colouration followed by curling symptoms. hands of workers. Lower sepals join together and enlarge to form a swollen calyx. implements and on the surface of seeds and sap. Mottling and vein-clearing symptoms are also seen. Flower buds stand erect and green. 11. rod-shaped bacterium with single polar flagellum. Internodes are shortened. No vector transmission. Infection on matured fruits shows internal necrosis. vesicatoria). The size of the leaf is much reduced. Leaflets are usually distorted. aplerotic. inter. intercalary or terminal. Damping off Symptoms: Seedling infection is seen as brown discolouration at the lower portion of the stem where the tissues later become soft. macroconidia and chlamydospores. Macroconidia are falcate and septate. Roots exhibit rotting. wedge shaped. which turns yellow and cause fruit drop.and intra-cellular. Frankliniella schultzei. single. brown. The place where the branch arises from the main stem becomes weak and necrotic leading to bending of branches from the main stem. If the bark of the stem is peeled. 2. brown and necrotic spots with concentric rings are seen on leaves.Symptoms: Leaves become reduced in size and exhibit thickened. occidentalis (Thrips). F. Zoospores are reniform in shape and biflagellate. Causal agent: Tomato spotted wilt virus (TSWV). pale yellow or yellowish concentric. Mycelium is coenocytic and hyaline. Conidia are produced singly. It produces microconidia. Necrotic irregular spots are seen on the leaf surface. Fruit spots are dark brown and sunken. brown streaks can be seen. Fungus: Pythium aphanidermatum. Conidiophores emerge through stomata. Leaves turn chlorotic. smooth and thick walled. Leaf exhibits characteristic bronzing and necrosis. 3. Chlamydospores are globose. bronzy veins. has 5-10 transverse septa and a few longitudinal septa. BRINJAL 1. Leaf dries due to bigger necrotic patches and then fall down. Leaf spot Symptoms: Irregular. Mycelium is septate. muriform. Leaves become flaccid and hang down. Mycelium is septate and hyaline. circular rings of mosaic mottling are observed. 2-celled and are formed in chain. Such diseased seedlings collapse at soil level. Fusarium wilt Symptoms: It attacks seedlings as well as matured plants. Vector: Thrips tabaci. Microconidia are hyaline. Oospores are spherical. fusca and F. On fruits. Zoospores are lobed. Fungus: Fusarium solani. Fungus: Alternaria solani. . Whitish fungal growth is seen on base of stem and roots. Pycniospores are oblong. In the seed bed. Alfa conidia are hyaline. Pycnia are formed as orange yellow pustules on the upper leaf surface. penicillariae. Phomopsis blight and fruit rot Symptoms: The pathogen infects the crop from seedling to harvest. brinjal. Pale sunken spots appear on fruits and later it covers the entire fruit. Rust Symptoms: The pycnial and aecial stages of pearlmillet rust are formed on leaves of this alternate host. The stem base is affected.. The internal portion of fruits rots and the whole fruit is mummified. Beta conidia (stylospores) are filiform. it causes damping off. Aecia are inverted cup-like structures formed near the epidermis. one-celled and fusoid. Flowers are phylloid and fruits are rare. The fruit is attacked while in the plant. hyaline and single celled. 8-spored asci. grey to brown spots with light coloured centre appear on leaves and the affected leaves turn yellow and die. Fungus: Phomopsis vexans. The leaves coming in contact with soil is affected. 5. 6. Alfa conidia and beta conidia. Circular or irregular. Axillary buds are induced to grow with small narrow and thin leaves. Causal agent: Phytoplasma . The upper surface of leaf become depressed and the corresponding lower surface become convex. viz. Fungus: Puccinia substriata var. Little leaf Symptoms: The infected plants exhibit general chlorosis and reduction in plant height. hyaline and one-celled. Pycnidia developed on the spots produce two types of conidia. Aeciospores are hyaline and spherical in initial stage but become polygonal. girdled and the plant topples down. Perithecia are in clusters containing clavate. Mycelium is septate. sessile. Internode length is reduced leading to clustering and overcrowding of leaves. Aecial cups are formed in groups on the lower surface of leaves. Leaf size is abnormally reduced. They are produced in chain. Ascospores are bluntly fusoid and 2-celled.4. Each cup has an outer wall called peridium made up of single layer of cells. The affected plant is severely stunted. Each ascus has two ascospores. which are hyaline. Cleistothecia are globose and dark. Conidia are cylindrical. Powdery mildew Symptoms: White or greyish white patches appear on the upper surface of leaf. As the disease develops. single celled and are produced in chain. Conidia are hyaline. 2. Severely affected leaves fall off. 3. Cercospora leaf spot Symptoms: Affected leaves show irregular. Severely affected leaves fall off. Later it covers the entire leaf surface. papery and wither. Veins are thickened. The spots increase in size and show concentric rings. The interveinal portions first exhibit small portions of green colour. Mycelium is ectophytic and haustoria are buttonshaped.Vector: Hishimonas phycitis (Jassid). 4. unicellular and oval. The fungal growth changes brown and the affected leaves dry and fall. The leaf size is reduced. sub-circular spots appear mostly on the lower leaves. thick. Fungus: Alternaria hibiscinum. malformed. Yellow vein mosaic / Vein clearing Symptoms: The green colour of main and lateral veins is bleached and the veins and veinlets exhibit yellow net work. olivaceous brown. Fungus: Cercospora abelmoschi. Conidiophores are pale olivaceous brown and multiseptate. fibrous and yellow. . barrel-shaped. Fruits are smaller. straight to curve and 1 to 8 septate. these green portions turn chlorotic and finally the leaves become yellow. Fungus: Erysiphe cichoracearum. BHENDI 1. brown spots with grey centre and dark coloured margins. Alternaria leaf spot Symptoms: Brown. Brinjal act as an alternative host crop for pearlmillet rust pathogen Differentiate 1. 2. The fruiting body of Phomopsis blight in brinjal is _______________ 4. Mention a phytoplasma disease in tomato True or False 1. 9 Date: DISEASES OF CUCURBITS. Fusarium wilt . POTATO. Questions to be answered 1. CRUCIFERS. Conidium of Alternaria is hyaline 4. Vector: Bemisia tabaci (Whitefly). How the damping off disease spreads? 3. Mention two important conditions which favour the development of damping off disease in tomato. BYVMV affects both quality and quantity of bhendi fruits 5. Bacterial wilt and bacterial canker of tomato 3.Causal agent: Bhendi yellow vein mosaic virus (BYVMV). Sclerotium rolfsii survives in the off-season as sclerotia 2. TAPIOCA AND SUGARBEET CURCURBITS 1. Fusarium wilt of tomato and Tomato spotted wilt 2. Erysiphe cichoracearum produces oidiopsis type of conidia 3. No. Mosaic and leaf curl of tomato Ex. black. Macroconidia are sickle-shaped and septate. Secondary microorganisms enter through the wounds in the lesions and cause rotting of fruits. Wilting progresses slowly. Oospores are not common. few and with poor taste. These spots become angular and bounded by leaf veins. sunken lesions. diseased and necrotic portion falls off leading to “shot hole”. Black acervuli contain conidia. Downy mildew Symptoms: Irregular white patches of downy growth are seen the surface of leaves. sunken lesions of varying size appear. Powdery mildew . Fungus: Fusarium oxysporum f. Drying and death of young seedlings occur. Fruits are dwarf. Chlamydospores are thick walled. It is an obligate parasite. Stem infection results in the formation of shallow water soaked. sp.Symptoms: Seedlings and grown up plants are attacked. niveum. Number of spots coalesces and leaves dry up subsequently. Young seedlings may damp off and die. In severe cases. single celled. Fungus: Pseudoperonospora cubensis. single celled and hyaline. which are 3. which later girdle the stem and cause death of shoots. The corresponding upper surface shows yellow patches. Sporangiophores arise in groups through stomata. In older plants margins show tip burning. Fungus: Colletotrichum lagenarium. thin walled provided with papilla at the distal ends. The sporangia are greyish. brown coloured. Entire leaf dries quickly. 2. It the older lesions black acervuli arranged in concentric rings are seen. On matured fruits circular. In older plants spots on leaves are yellowish brown. Angular to roughly circular with a yellow halo. Young leaves are less susceptible than the older leaves. In wet weather. Affected fruits ripen and become yellow and the flesh become tuff and insipid. oblong. The mycelium is coenocytic. ovoid. Anthracnose Symptoms: All the above ground plant parts are attacked. Young fruits shrivel with dark colour. When moisture is present the centre of the spot shows gelatinous mass of pink coloured conidia. dichotomously branched and bear sporangia. 4. Microconidia oval. intercellular and is with ovate haustoria. dead stems show white or pinkish mass of fungal growth. Spots are small. They increase in size and show concentric rings on the upper leaf surface. Fungus: Alternaria cucumerina. 8. 6. Conidia are single celled. In wet weather. lachrymans. The leaves turn brown and dry. Mycelium is hyaline. Conidia are hyaline. They coalesce to form large blotches. Conidiophores are light brown and geniculate. bacterial ooze is seen on the water soaked areas which later dries to form white crusts. barrel-shaped produced in long chains. Cucumber mosaic . 7. Gram negative and motile by 1 to 5 polar flagella. septate and superficial. Cercospora leaf spot Symptoms: Commonly seen in snakegourd. 5. The spots enlarge and turn brown. Mycelium is septate and coloured. hyaline. dark and muriform in shape. Alternaria blight Symptoms: Water-soaked circular leaf spots appear on the leaves. It is with 1-9 transverse septa and 1-7 longitudinal septa. circular to irregular with greyish centre and black margin. Bacterium is rod-shaped. Cleistothecia are globose and dark with myceloid appendages. Fungus: Erysiphe cichoracearum. Later they cover the entire leaf surface. deformed and the quality is also reduced. young green stems and fruits. cylindrical and septate. Mycelium is septate and coloured. Fungus: Cercospora lagenariae. Bacterium: Pseudomonas syringae pv. The necrotic tissues dry and fall off leaving irregular holes. Leaves dry and die. Premature defoliation and death of vines occur. irregular or angular lesions appear on the leaves. Yellowish green pigment is produced in the culture. Watersoaked. Angular leaf spot Symptoms: Disease occurs on leaves.Symptoms: White or dirty grey powdery growth is seen superficially on the upper surface of leaves in patches. Conidia are obclavate. Circular spots appear superficially on fruits. Young succulent stems and petioles are also attacked. Fruits are undersized. Flowers are dwarfed and few in number. Club root Symptoms: Infected plants at first have pale green to yellowish leaves. which results in flagging of the leaves. A. Fungus: Alternaria brassicae.0 to 7. Conidiophores are thick and brown. Later. A. They join together to form bigger lesions. Fungus: Plasmodiophora brassicae. Most characteristic symptoms are seen on the roots. Older and larger clubbed roots disintegrate before the end of the season because of invasion by bacteria and other fungi. Black leaf spot / Alternaria leaf spot Symptoms: Light brown to black spots appear on the leaf surface. Affected leaves become yellow and fall off.5 cm in dia and show concentric rings. infected plants show wilting in the middle of the hot. Vector: Aphids craccivora. Fruits are small with yellowish green mottling. Internodes are shortened. The lateral roots and rootlets are also converted into spindle-like-swelling. gossypii and Myzus persicae (Aphids). Hypertrophy causes malfunctioning of xylem. evonymi. which recover during night. 2. Affected roots are small and show spindle-shaped or club-shaped swellings due to hypertrophy and hyperplasia. Conidiophores are thick and geniculate. Young plants are killed while older plants remain alive but stunted and fail to produce marketable heads. It is also transmitted by sap and grafting. sunny days. Lesions on stems and petioles are linear. resting spores (hyaline ad spherical) and anteriorly biflagellate primary and secondary zoospores. Causal agent: Cucumber mosaic virus (CMV). Leaves attain only half the size of normal leaves. Affected leaves are puckered and deformed. The fungus produces plasmodia. Conidia are both transversely (11-15 septa) and vertically . The fungus attacks cabbage heads mostly after harvest and with Rhizopus it causes brown rot.Symptoms: Leaves show clear mosaic symptoms. Spots are spherical to irregular in shape and may be upto 5. CRUCIFERS Cabbage and Cauliflower 1. spherical. Each sterigma bears a sporangium at its tip. Petals will look like sepals and stamens become leaf-like. When young stems and inflorescence are infected or when the infection has occurred from soilborne oospores in the seedling stage. which leads to swellings and distortions. Mycelium is inter. Floral parts are deformed. Mycelium is intercellular. White rust Symptoms: Prominent white or creamy yellow pustules of 1 to 2 mm dia are mainly observed on the lower surface of the leaves. Fungus: Albugo candida. coloured and beaked. It is an obligate parasite. Affected inflorescence increase 12 to 15 times in size. Dichotomous branching occurs 6 to 8 times at the tip of the final branches. Floral organs become partly or wholly swollen. Oospores are globose and yellow. fleshy. Greyish white downy fungal growth appears on the under surface of the leaves while the corresponding upper surface show yellowish spots. Sporangia are not papillate and germinate by germ tubes and not by zoospores.septate (0-3 septate). stems and inflorescence. Blisters appear on the stem and inflorescence. It is an obligate parasite. dichotomously branched at acute angles and final branches (sterigmata) are with curved pointed tips. hyaline and are arranged in chain. the fungus becomes systemic and causes hypertrophy and hyperplasia of floral tissues. Conidia are mostly solitary or chains up to 4. Sporangiophores are erect. Veins and veinlets turn black and the leaf tissues become . haustoria are finger-shaped. Black rot Symptoms: Disease causes development of “v” shaped chlorotic to yellow lesions from the leaf margin. (Cystopus candida). 5. Sporangia are single celled. The stems show dark brown and depressed lesions. which later develop downy growth of the fungus. Ovules and pollen grain are atrophied. The upper surface correspondingly exhibits yellow patches.and intra-cellular. green or violet in colour. Ovary is sterile. Fungus: Peronospora parasitica. 4. Early infection causes stunting of plants. Downy mildew Symptoms: The fungus infects leaves. Cauliflower curds look brownish at the top. 3. Infection at the seedling stage may cause complete death of seedlings. Axis is inflorescence and flower stalks are enormously thickened. Sporangiophores are club-shaped and hyaline. Infected leaves dry up and fall off. 2. White fungal growth is seen at border of the lesions on lower surface of leaves. On tubers purplish or brownish blotches develop on the exposed side over the soil. Mycelium is brown and septate. Vascular tissues in affected plants become conspicuously black followed by internal breakdown of fleshy tissues. The tissues of the tuber become reddish brown upto 5 to 15 mm into the flesh of the tuber. Internal tissues turn brown and corky. Stem breaks at this point and the plant topples over. Lesions progress towards the midrib from where systemic infection spreads into stem and root. dry and become brittle. Secondary fungi and bacteria causing soft rots may subsequently invade infected tubers. Black sunken spots are seen on succulent seed stalks and siliqua. The disease spreads to petioles.necrotic and brittle. POTATO 1. Fungus: Phytophthora infestans. campestris.. On the stem. circular or irregular with concentric rings. Several spots coalesce and cover the entire leaf. The leaves show dark brown. Late blight Symptoms: On the leaves water-soaked lesions develop which later enlarge rapidly and cover the entire surface. Mycelium is hyaline and coenocytic. The rot continues even after harvest. Heads of cauliflower are invaded and discoloured. Bacterium: Xanthomonas campestris pv. Brown spots are found on the surface of older leaf and subsequently spread to top younger leaves. Later the affected areas become firm and dry and somewhat sunken. Soon entire leaf is infected and dies. They are oval. Conidia are yellowish brown with vertical and cross septations (5 to10) and provided with a prominent beak. It is a Gram negative and rod-shaped bacterium. Early blight Symptoms: Disease is present both in hills and plains. black lesions are observed on nodes. The branches will . Such rotting tubers emit putrid smell. rachis and stem. circular or irregular sunken spots. Symptoms are observed on petioles and stem as brown lesions. Conidiophores emerge through stomata and are dark brown. They are formed singly at the tip of conidiophore. Fungus: Alternaria solani. Young plants may be killed in the seed bed. The sporangiophores emerge through stomatal opening with branches. They are less than 1 cm in dia. erect and septate. These spots turn purple brown and finally black in 2 to 3 days. On the lower surface the lesions have less distinct margins and in the centre brown spots assume a greyish lust because of conidiophores and conidia. Brown leaf spot Symptoms: Spots are seen on both the sides of the leaves. TAPIOCA / CASSAVA 1.4 polar flagella. Conidia are produced singly at . Indefinite halo is seen around the lesions. Oozing of bacteria may be seen along the rings. Tubers exhibit rotting at harvest and during storage. Fungus: Rhizoctonia solani. dry and drop off. a brown. Sporangia are pear-shaped or lemon-shaped. elliptical to obclavate and thin-walled. Small veins within the lesions appear black. Sclerotia on plant tissues are black. Adhering soil particles easily recognizes infected tubers. septate and branches at right angle to main axis. circular ring-like discolouration (of vascular tissues) is seen near the periphery. The spots are irregular or angular and restricted by leaf margin or veinlets and measure 3 to 12 mm in dia. Fungus: Cercospora henningsii (Mycosphaerella manihotis). Bacterium: Burkholderia solanacearum. sunken. hyaline and single celled with papilla. The inner portion of the stem turns brown or black. 4. Later they die. Brown Rot/ Bacterial wilt / Ring disease Symptoms: It is noticed at tuber formation stage. The wilted plants initially recover in the morning or evening but wilt in the afternoon. Each sporangium releases 3 to 8 zoospores. On the upper surface. the spots appear uniformly brown with a distinct dark brown border. The basidiospores are hyaline. As the disease progress the leaves turn yellow. Black irregular sclerotia are found in the skin are observed on the tubers. Black scurf and stem canker Symptoms: Brown. Conidiophores are olivaceous brown. Skin of the affected tubers is discoloured. geniculate and sparingly septate. 3. circular or elongated lesions on the lower portion of sprouts.have nodular swellings. Tubers exhibit brown discolouration. The bacterium is Gram negative. rodshaped and motile by 1 . Plants exhibit wilting and leaves hang in a flaccid condition. When the affected tuber is cut open. Mycelium is hyaline to coloured. 2 to 8 septate and pale olivaceous. Perithecia are brown to black. Leaves are reduced in size. Vector: Bemisia tabaci (White fly). 2. misshapen and twisted with bright yellow areas separated by normal green tissue. They are slightly curved with both ends bluntly rounded. Sclerotium root rot Symptoms: The disease is observed on cuttings and on matured roots and tubers. uniseptate and constricted at the septum. Damping off and Root rot Symptoms Damping off: It causes pre-emergence and post. dark brown and are found mixed with mycelium. . Rotting initiates from cut ends and spreads throughout the cuttings. eight spored and sessile. Causal agent: Indian Cassava mosaic virus (ICMV). Ascospores are ovoid. Fungus: Sclerotium rolfsii.emergence damping off. Rotting of roots and killing of young plants are seen. White mycelium radiates into the soil from infected roots or stem base. The fungus produces sclerotia. SUGARBEET 1. Cassava mosaic Symptoms: Infected leaves exhibit chlorotic areas and distortion in leaflets. Surface blisters which later ruptures the epidermis expose black perithecia. 3. Asci are elongate. Tubers show longitudinal splitting. clavate.the apex of each conidiophore. Fungus: Glomerella cingulata. 4. Glomerella stem rot Symptoms: It is common in stored cassava cuttings and old stem debris in cassava fields. which are round. P. 3. 2. Beneath these lesions pockets of spongy tissues develop. Numerous small.Root rot: This phase is characterized by yellowing. bataticola – The sclerotia measure up to 1 mm in dia. In addition to P. On the petiole pycnidia are seen. The oospores serve as overwintering / oversummering organs and are the primary source of inocula in the soil. Root rot affected plants can be easily pulled out.The lesions extends towards the base and show severe necrosis of root rip. Phoma disease Symptoms: The fungus produces the following symptoms Seedling blight: Diseased seedlings exhibit black lesions on primary roots. Mycelium is hyaline. Rhizoctonia root rot Symptoms: It causes crown rot and dry root rot of sugarbeet. Fungi: Rhizoctonia solani – The sclerotia are irregular. wilting and drying of the plants involving all the aerial parts. just below the collar region. the fungus produces globose pycnidia and hyaline. roots in upper 1-2 cm layer show sunken lesions. aphanidermatum. Fungus: Sclerotium rolfsii. Infected roots show externally a deep brown discolouration. The fungus causes rotting of roots and tubers. basal portion of the petiole blackens and subsequently the entire crown of the plant rots. oval to elliptical pycnidiospores. In the pycnidial stage. In dry root rot. bataticola: It causes charcoal rot mostly in crops over four months age. black. round sclerotia are seen on the diseased roots. debaryanum and P. In crown rot.7 to 3. Fungus: Pythium aphanidermatum.0 mm in diameter. The fungus also produces both terminal and intercalary barrel shaped chlamydospores. . brown to black and are 5 mm in dia. branched and septate. R. R. ultimum are also responsible for causing damping off and root rot. 4. Sclerotia are round to oblong and measure 0. Sclerotium root rot Symptoms: The disease attacks the plant and causes yellowing and wilting. . Alternaria leaf spot Symptoms: The pathogen attacks both young and older leaves. In later stages. turn dark brown with concentric rings. Powdery mildew Symptoms: The disease appears as round whitish patches on the upper surface of the leaves. Later they increase in size and may cover the whole leaf surface. Fungus: Phoma betae The fungus produces pycnidia and pynidiospores. yellowish brown and appear on both the surfaces. Infected seeds become black. The pathogen survives on the infected crop debris and seeds buried in soil as conidia. 6. Older leaves are more susceptible than the younger leaves. 5. Infection spreads from lower end to the upper end of flowering stalks. Pathogen is both seed and soil-borne. The spots produced by A. Black dot-like pycnidia are often observed on the spot. Primary infection is through seed-borne inoculum and the secondary spread is through rain splashes and irrigation water. Stem rot: Infected plants remain stunted and ripen prematurely. 7.Leaf spot: Necrotic spots of circular to oval with light to dark brown concentric rings with diffused margin appear on the leaves. The spots increases in size.The spots are minute. Fungus: Alternaria alternate and Alternaria brassicae. brassicae are dark dark brown and circular and are up to 1 – 5 cm in dia. these spots coalesce to form large patches Fungus: Cercospora betlicola. Secondary spread is through wind-borne conidia. water-soaked. The central necrotic portion dry and fall off resulting in shot holes. The fungus persists in the fields on decayed plant refuses and the secondary infection takes place by the air-borne conidia. Cercospora leaf spot Symptoms: Minute translucent spots surrounded by yellowish green halo appear on lower leaves. Severe infection of basal stem leads to withering of plants. alternate are black and irregular and measure up to 1 cm in dia and the spots produced by A. Storage rot: Tubers from diseased plants carry incipient infection of the fungus and cause rotting during storage. Conidia from plant debris cause primary infection. The diseased leaves wilt and dry. wind-blown soil and cultural operations. The bacterium survives in infected plant debris and in the soil. Under moist conditions the dead parts become slimy and necrosis spreads quickly in to the veins and the leaf petiole. shallow and deep scabs are found in sugerbeet. hyalilne. Sporogenous hyphae are spiral in form. Several lesions occur in single cotyledon and cause distortion. Serious infections cause blighting of leaves and stalks. Bacterial scab Symptoms: Small. Gram negative. 8. Later they enlarge. unicellular and thin walled. Bacterium: Pseudomonas syringae. Air-borne conidia cause secondary infection in the field.Fungus: Erysiphe betae. soft and black. Bacterium: Streptomyces scabies. Bacterial blight Symptoms: Symptoms usually appear on the leaves of young seedlings. Spores are produced by the formation of septa at intervals along the hypha which contract to form narrow isthmuses between the cells. The bacterial are spread through soil water. Mycelium is on the upper surface of host leaves. The fungus survives in the form of cleistothecia in infected plant debris. rod shaped bacterium with polar flagella. Two types of scab viz.The spores germinate by means of one or two germ tubes. Conidia produced on condiospores are barrel shaped. 9. wart-like growths are sparsely scattered over the tap root and often they are concentrated in bands. brownish and slightly raised spots appear on fleshy tap root.. 10. Young roots are more susceptible to infection than older roots. Small depression appears on either side of the cotyledons which become water-soaked. Heart rot Heart rot or brown heart or internal black spot is caused by deficiency of boron. The upper stem and inflorescence are streaked dark brown and necrotic blotches appear on the leaves. branched without cross walls and at maturity these aerial hyphae forms chain of three to many spores.The rounded. coalesce and become very corky. Questions to be answered . Bacterium is seed-borne. The hyphae are slender. Leaf spot with concentric rings is common in Cercospora 2.1. Production of shot-hole symptom is a characteristic feature of Collettrichum 4. Early blight and late blight of potato Ex. Mention thesexual spore produced by white rust pathogen 4. Sometimes a yellow halo develops around each lesions. Purple blotch / Scald disease Symptoms: This occurs mainly at the top of the leaves. The lesions develop towards the base of the leaf. What is hypertrophy and hyperplasia? 3. GINGER. CHILLIES. CORIANDER. Bacterial ooze is seen in potato tubers infected with brown rot pathogen Differentiate 1. No. GARLIC. Longitudinal splitting of tubers is observed in cassava infected with ICMV 6. The infection starts with whitish minute dots on the leaves with irregular chlorotic areas on tip portion of the leaves. 10 Date: DISEASES OF ONION. The leaves break at the . BETELVINE AND PEPPER ONION 1. Later circular to oblong concentric black velvety rings of fruiting bodies appear in the chlorotic area. Downy mildew and powdery mildew of cucurbits 2. TURMERIC. The teleomorph of Cercospora henningsii is ___________ True or False 1. Cleistothecium is an asexual fruiting body produced by powdery mildew fungus 3. What is plasmodium? 2. Sporangia are the asexual spores of Erysiphe 5. Downy mildew and white rust of crucifers 3. tapering to the beak. Fungus: Fusarium oxysporum f. Conidia are solitary. 3. Each ball consists of an enveloping cortex of tinted. The leaves turn yellow and then dry up slowly. Infected plants are killed within 3 to 4 weeks of emergence.sp. Conidiophores arise singly or in groups. The spores are found in permanent balls. septate and mid brown. These lesions develop into thickened areas of several millimeters in size. coloured and septate. The spores germinate by means of a short promycelium while still in the ball. The sori of Urocystis contain dark coloured and powdery spore masses. Dark lesions occur on the cotyledons as they emerge. Smut Symptoms: The fungus attacks seedlings. The beak is about the same length as the body. distorted leaves bearing lesions throughout their length. There will be a whitish mouldy growth on the bulb scales. Bulbs are usually small. mid-golden brown and smooth. The entire plant shows complete drying of the foliage. It occurs in patches. instead hyphae break apart into independent units and these cells function as spores producing thalli. They are with 8 to 12 transverse septa and zero to several longitudinal septa. . The bulbs decay in storage. straight or curved and obclavate. Bulbs become dry and papery. cepae. Fungus: Alternaria porri.point of infection and hang down. The sterile cells are smaller than the spores. 2. The promycelium does not produce the apical whorl of sporidia. In the matured plants numerous black blisters are found both on the leaves and bulb scales. The infection is also seen on the outer scales of the bulb. The disease causes premature drying of the foliage which results in poor development of bulbs. The lesions burst open and release masses of black spores. Mycelium is branched. sterile bladder-like cells with one or two central dark coloured thick-walled chlamydospores (smut spores). brittle. Basal rot / Bulb rot Symptoms: The disease is seen from 30 days old crop. sometimes geniculate. The fungus produces many chlamydospores which are thick walled resting spores and microconidia (one celled thick walled). The beak is flexuous. The affected plant shows drying of the leaf tip downwards. pale and is tapering. The bulb shows soft rotting and they get rotted. Fungus: Urocystis cepulae. The body of the conidium may be ellipsoid. Surviving plants are stunted with short. straight or flexuous. The conidiophores are non-septate and swollen at the base. Conidia are hyaline. 5. Fungus: Colletotrichum circinans. The plants are stunted with succulent neck. The fungus produces acervuli which contain thick walled. Mycelium is coenocytic and intercellular with filamentous haustoria. In local infections caused by wind-borne conidia. Branching is dichotomous. dark. They germinate by one or two germ tubes. The fungus can invade floral parts and can infect a small proportion of the seed. These conidia germinate by one or two germ tubes. Downy mildew Symptoms: In systemic infection (when the plants are grown from a diseased bulb) the plants remain stunted distorted and pale green. sunken and yellow lesions. fusiform and one celled. . Such plants produce only undersized bulbs.4. Oogonia are formed in the intercellular spaces. Conidia are pyriform and attached to the sterigmata by their pointed end. Inner leaves are then affected but new and young central leaves remain healthy. If the leaf is attacked in the middle part. the fungus develops as white to purplish downy growth on these spots. Subcuticular black smudge (black stroma of the fungus) is seen on bulb. Succulent necks are subject to attack by fungi and bacteria in storage. Usually the older leaves are attacked first and the infection spread to the sheath. In dry weather and only white spots are seen. When seen with hand lens bristles can be seen inner scales show small. The black colour may be uniform or it is with circular lesions with concentric rings of dark stroma and mycelium. Under humid weather pinkish mass of spores are seen. In humid atmosphere the downy growth of the fungus develops over the entire leave surface. Fungus: Peronospora destructor. Sterigmata are subacute or acute. 0-3 septate setae. oval to cylindrical pale spots are formed on the leaves containing alternating green and chlorotic zones. neck or green leaves which are clinging to the bulb after digging. Smudge Symptoms: It is a disease of scales of the bulb and appears at any time in the plant and during transport or storage. Mycelium is septate and branched. In humid weather. it drops from the point of infection and the tip dries. Infected bulbs lose their pungency and smell. The individual bulbs shrivel and are light in weight. 4. Affected scale tissue become soft. The infection spreads down the scales which have been originally infected. It manifests itself with the copious growth of a dust-like fungal mass which remains concealed mostly between the scales.GARLIC 1. Fungus: Macrophomina phaseolina. In the case of bulb rot caused by Fusarium failure of germination and drying of leaves from the tip can be noticed. Fungus: Aspergillus niger. Rotting of bulb and production of side shoots produces clump of shoots. The above ground symptoms are stunting and yellowing. Pink root Symptoms: The roots turn pink or reddish and sometimes darken to a red or purple colour. Dense layer of grey mould appear at the neck.sclerotium . 2. Macrophomina rot / Internal bulb rot Symptoms: It is a storage rot. Aspergillus rot / Black mould blemish Symptoms: It is also storage rot. Black pinhead-like sclerotia develop over the fleshy scales which are light in weight. 3. Fungi: Botrytis allii and Fusarium oxysporum. No external symptom can be observed unless the outer scales are removed. brown mostly shriveled but do not lost their pungency. Black spores form on the diseased roots which eventually shrivel and die. A. Neck rot and bulb rot Symptoms: It is commonly found on bulbs at the time of harvest. The whole tissues are transformed into a black powdery mass. Fungus: Pyrenochaeta terrestris (Syn: Phoma terrestris). Dark sclerotia appear on the older decayed tissue. tip burn and die-back of the leaves. Diseased plants can be easily pulled.alliaceous and A. corianderii. 3. Chlamydospores germinate in water and form sporangia and spores.CORIANDER 1. The fungus hyphae are intercellular. The fungus survives in seed and soil as chlamydospores. Partial wilting is also found. Wilt Symptoms: The plants are attacked at all stages of growth. As they mature they become surrounded by a thick. Curvularia sp. The disease can be easily recognized in the field by drooping of the terminal portions. three layered wall and attain a dia of 50 – 60 microns. Minor diseases Powdery mildew – Erysiphe polygoni Grain mould – Alternaria sp. Fusarium sp. hyaline. Stem gall / Tumour Symptoms: The disease appears in the form of tumour-like swellings of leaf veins. followed by withering and drying of leaves. Fungus: Fusarium oxysporum f. septate and broad. Seeds if formed are immature and light. sp. The severity of disease increases with age. The size of the swellings vary according to the dimension of the part infected. micro conidia and chlamydospores. eventually resulting in death. Fungus: Protomyces macrosporus. The swellings are usually elongated and 9-12 mm x 3-5 mm dia. Exospore is thick and brown.. . The swellings on the veins give a swollen hanging appearance to the leaves. leaf stalks. Severe infection in the early stage results in total failure of the crop. Soil-borne inoculum is the primary source of infection. Wilting is sudden instead of being gradual. 2. Discolouration of vascular system of the root is observed. peduncles. The released spores from sporangia are connected in pairs and later they fuse. The pathogen remains viable in the seed for five months and can survive for longer period in the soil. and Helminthosporium sp. Scattered cells in the hyphae swell and form ellipsoidal or globose bodies which later develop into chlamydospores. stem and fruits.. Chlamydospores show 10 % germination after six years. The fungus is restricted to tumours and become rough. In very severe cases the plants are killed. The fungus produces macro. Sterility is often noticed in such plants. Meso and endospores are thin. Each ascus contains eight ascospores. plants wither and dry. Colletotrichum leaf spot Symptoms: The spots are elliptic and oblong with greyish white centre. Fungus: Pythium aphanidermatum. Rhizomes get discoloured. Colletotrichum leaf spot 2. 2. Infected plants can be pulled out from the soil easily. Internal mycelium forms stroma and setae. brown. leaf tips turn yellow and infection gradually spreads down to the leaf blade and leaf sheath along the margin. Oospores are produced. Often the middle portion of the lamina remains green while margins turn yellow.TURMERIC 1. soft and form a putrefying mass. Spots coalesce and leaves dry. Mycelium is intercellular and haustoria are branched or lobed. zoospores are reniform in shape and biflagellate. It is a complex disease and is more predominant. single celled and falcate. Mycelium is inter-and intra-cellular. The mycelium is hyaline and coenocytic. brown margin and yellow halo. Rhizome rot Symptoms: Affected plants become pale. Conidia borne on conidiophores are hyaline. Fungus: Taphrina maculans. Leaf blotch Symptoms: Spots appear on both the surfaces of the leaves. Fungus: Colletotrichum capsici. Leaf blotch : As in turmeric : As in turmeric . It first appears as apple yellow discolouration turning to dirty yellow and then brown with chlorotic halo. mis-shaped. Leaves droop. Ultimately the leaves dry up. Sporangium is lobulate. Spots coalesce forming large necrotic blotches. GINGER 1. Root systems are heavily damaged. 3. oblong and are with rounded ends. fruits shrivel. hyaline and sickle-shaped conidia. Alternaria leaf spot . In the acervulus. Fungus: Colletotrichum capsici. hyaline and branched. Phyllosticta leaf spot Symptoms: Small. The spots coalesce and cause extensive discolouration. Such branches are devoid of leaves and flowers. dry and fall off. The fruits become white in colour and loose their pungency. dark brown and septate. Affected portion becomes dirty white. Stem shows die-back symptoms. hyaline. The fungus produces pycnidia. Black dot-like acervuli are found scattered on affected stem. elongated spots of 1 to 10 x 0. Damping off Symptoms: Infection is observed in young seedling. Watersoaked lesions are noticed on fruits. The oospores are spherical and thick walled. 3. In between setae a layer of hyaline single celled conidiophores are produced. The conidia are CHILLIES 1.3. They bear single celled. Mycelium is coenocytic. Acervuli are also seen on surface of the buds. They are intercellular and intracellular. papery white centre and yellow halo.5 mm size appear on the leaves. Collar region becomes watersoaked and the affected portion is soft and weak. Seedlings collapse and topple down at soil level and die. Fungus: Pythium aphanidermatum. Matured spots will have a dark brown margin. Sporangia are lobed and hyaline. It is followed by premature leaf fall. Die-back and fruit rot Symptoms: Symptoms are seen on stem and fruits. rigid sterile structures called setae arise from the stoma. 2. Branches die from tip downward. Infection at pedicel and tips of branches causes shedding of flowers and flower buds. oval. Gappiness in the nursery is noticed due to death of seedlings in patches. Fungus: Phyllosticta zingiberi. Petioles and young stems are also . Bacterial leaf spot Symptoms: Water-soaked. macroconidia (falcate with blunt apical cells) and chlamydospores (globose or oval. sub-hyaline to coloured multiseptate.and intracellular mycelium. Fungus: Cercospora capsici. Leaves in the branches droop. Powdery mildew Symptoms: White talcum powder. smooth or rough walled. 4. inter. Conidiophores are long. Conidia are single muriform with both cross (5-10) and vertical septa and provided with a beak at the tip. Diseased leaves become yellow and fall prematurely. Very often it covers entire leaf surface. Fungus: Alternaria solani. septate. Corresponding upper surface turns yellow. 5.Symptoms: Irregular. roots are brown and poorly developed. Spots are seen on the stalks and stems also. Conidiophores emerge through stomatal opening in clusters of 3 or 4. The pathogen produces microconidia (hyaline. Severely diseased leaves become yellow and are shed. Conidia needle-shaped. A narrow halo surrounds each spot. Fungus: Leveillula taurica. These spots are with grey centre and brown margin. Seeds in affected fruits are discoloured. Fusarium wilt Symptoms: Leaves loose their turgidity and become flaccid. Spots are circular or irregular and cankerous. Infected leaves drop off prematurely. 7. In the diseased plants. Conidia are club or pear-shaped. become yellow and dry. broad at the base and taper towards the tip. single celled and hyaline. 6. Mycelium is purely endophytic.like growth is seen on the lower surface of leaves. intercalary or terminal). Fungus: Fusarium solani. Fruits show brown irregular spots with dark brown margin. The fungus produces brown. The spot bulges and turns purple with black centre. Cercospora leaf spot Symptoms: Oval or oblong spots appear on leaves. hyaline and septate. cylindrical and 2 celled). brown to dark brown spots with concentric rings observed on the leaves. scattered brown spots appear on the leaves. gossypii and Myzus persicae (Aphids). b. a. Fruits show chlorotic streaks and rough skin. . Mosaic Symptoms: Mosaic mottling. Small rings are also found on the leaves.attacked . Bacterium: Xanthomonas vesicatoria (Syn. Diseased green fruits turn brown or black. On the green fruits round.gossypii and Myzus persicae (Aphids). Vector: Aphis craccivora. Leaf curl Symptoms: Lower and upper curling of leaves accompanied by puckering and blistering of interveinal areas and thickening and swelling of veins are the main symptoms. A. pv. blistering and deformation of leaves. It is a rod shaped bacterium with polar flagellum. Fruiting is stopped and if formed they are small and deformed. 8. Vector: Aphis craccivora. Leaves become filiform. Xanthomonas campestris vesicatoria). exhibit mosaic mottling. Causal agent: Cucumber mosaic virus (CMV). crinkling. Internodes are shortened and plants are stunted. 9. Causal agent: Potato virus Y. vein banding. A. Mottling symptoms are observed on fruits also. smalling of leaves and interveinal chlorosis of infected leaves. raised spots with depression in the centre are seen. Causal agent: Tobacco leaf curl virus (TLCV). Vector: Bemisia tabaci (Whitefly). Flowers and fruits are few in infected plants. Mosaic Symptoms: Infected plants are bushy. brown coloured. If the seed vines are planted late during cold weather the establishment of the vine is very poor. Sclerotium wilt Symptoms: The vine is susceptible at all stages of its growth. The lower portion of the stem near the soil region shows irregular. In the early stages. 2. The affected plants dry up completely within two or three days. The succulent stem turns brown. The initial symptoms of the disease are sudden wilting of vines rows after rows. The diseased internodes undergo a wet rot and the tissues become soft. The affected vines show yellowing and drooping of leaves with tip downwards. Seed vines snap at the nodes and get rotten. becomes soft and the bark peels off easily. the affected leaves show yellowing on the upper surface with a downy fungal growth on the corresponding lower surface of the leaf. Whitish cottony mass of fungal mycelial growth is seen on the stem and roots. Fungus: Phytophthora capsici. Such affected leaves fall off prematurely. The leaves near the soil region show circular to irregular water-soaked spots. Later these spots turn brown. slimy and completely rotten exposing the fibrous parts. Darkening stem turns black in colour. . The stem portion buried in the soil snaps at the nodes due to rotting. water-soaked lesions. The stem rots at the point of attack and darkens up to 10 to 12 mm above the soil line. Darkened portion of the stem shrinks. Brown coloured mustardlike sclerotia are formed on the stem and also on the soil near the basal part of the plant. Leaf rot: Leaf rot is seen in the young crop. Stem rot: The rotting due to the fungus is mainly confined to the stem portion buried in the soil and above the soil level. The affected plants show drooping of leaves and they dry up ultimately. brittle and dry as stick. The leaves become dull due to the loss of lustre.BETELVINE 1. The roots at the nodal region show black discolouration and rotting. Sometimes affected spots rot and disintegrate. This results in gappiness in the field. The plants are usually affected at the collar region. Phytophthora foot rot and leaf rot / Stem rot Symptoms: Foot rot: The fungus attacks the veins at all stages of crop growth. Such leaves turn pale and fall off easily. brown to dark brown. The hyphae are hyaline when young and become white to ash coloured with age. Infected leaves fall off prematurely. Anthracnose Symptoms: Generally older leaves show small. septate. The area surrounding the spots show yellow halo. Affected leaves fall off prematurely. Sclerotia are spherical. The dots develop close to each other in cluster. On the stem. Conidia are sub-hyaline straight or curved. When the spots are present on the margin of the leaves. Later. two or three streaks coalesce and encircle the stem completely. Haustoria are sac-like. 5 to 15 septate. The infected regions gradually become thin and dry and do not undergo any rotting.Fungus: Corticium rolfsii (Sclerotium rolfsii Sacc. black. They are unicellular. Powdery mildew Symptoms: The disease occurs on the tender shoots. The . Fungus: Cercospora piperis-betle. 2 to 3 septate and bear conidia in chains of 3 to 10. circular specks appear under the green bark. The affected leaves turn pale yellow and dry up. The disease appears as whitish powdery patches on both the surfaces of the leaves. Conidiophores are non-fasciculate. nongeniculate. These spots enlarge in size and develop to a size of 2 cm dia. leaf blade tends to droop owing to the shrinkage of tissues. Cercospora leaf spot Symptoms: The disease appears as minute deep brown to black dots especially on the margins and tips of older leaves. olive-brown.). 5. Such infected leaves are generally rejected at the time of picking or harvest. Acervuli as black dots are seen on the spots. truncate at the base with acute tips. The spots become concentric with a light yellow halo. Fungus: Oidium piperis. In older leaves the fungus causes light brown blotches and such affected leaves are rejected when the leaves are picked for marketing. 4. 3. brownish black and circular spots. These specks increase in size and form into narrow streaks. Affected leaves get shriveled and deformed and the margins of the leaves turn inwards. buds and leaves and affects the crop at all stages. Conidiophores are simple. smooth and are found mixed with mycelium. shiny. Mycelium is septate. Some times the central dead portion of the spot is found to fall off causing a shot-hole symptom. Conidia are cut off in basipetal succession. hyaline and barrel shaped. These leaves lose their lustre and turn yellow and fall off. The infection spreads to a larger area and becomes necrotic. Fungus: Phytophthora capsici. Bacterial leaf spot Symptoms: This disease is common in wet weather. Gummy ooze is seen during wet weather from these spots and the ooze turn into yellow deposits on the lower surfaces of the leaves. 6. Fungus: Colletotrichum capsici. Stem breaks off at the nodes.stem above the diseased internode wilts rapidly. betlicola. Bacterium: Xanthomonas campestris pv. On the leaves dark brown spots appear and enlarge causing concentric zonations with grey centre. A yellow halo surrounds each spot. Discoloured . The bacterium is Gram-negative. The vine above the point of stem infection gets killed ultimately. slimy. 2. Pollu disease / Anthracnose Symptoms: Spots on leaves are brown to dark brown. The stem infection spreads to the adjoining vine also in the same standard through injuries that occur during the tying operation of vines. The bacterium produces yellow. PEPPER 1. The vine dies in 3-4 weeks (Quick wilt). Leaves turn yellow flaccid and droop. circular and shiny colony on the medium. Affected leaves and spikes are shed. Infection on aerial branches causes die-back. On the berries water-soaked dirty brown sunken areas appear. Acervuli of the fungus are found on stem lesions. rod shaped and is motile by polar flagellum. These spots become angular and are surrounded by a yellow halo. Quick wilt / Phytophthora foot rot Symptoms: A dark patch appears on the stem and spreads to 30 cm from the base of the plant. Sometimes the spots are confined to the interveinal space. The affected leaves show minute water-soaked angular spots on the lower surface of the leaves. Spots exhibit coalescence and form bigger lesions with concentric zonations. Berries split at the lesion site. The word “pollu” in malayalam means a hollow. single -–elled and oval in shape. Questions to be answered 1. Berries dry up resulting in hollow and chaffy berries. The alga produces thallus.berries occur in groups of two to five. Smut and downy mildew of onion 2. Black dots appearing on the chilli fruit infected by Colletotrichum capsici represent ________________ 4. All the structures are coloured. 3. Write the mode of spread of purple blotch of onion 2. __________ and _______ crops 5. Intense spotting causes withering of leaves. Leaf curl and mosaic of chillies 4. Colletotrichum leaf spot and leaf blotch of turmeric . Red scaled onions are susceptible to Colletotrichum circinans 2. Colletortichum capsici infects ________. Phytophthora foot rot and Sclerotium wilt 5. Alga: Cephaleuros sp. Mycelium is septate and dark. sporangiophores and sporangia on the host. Damping off and Fusarium wilt of chillies 3. The chemical which prevents the entry of Colletotrichum circinans in onion is ________________ 3. Spots turn green on maturity. Red rust Symptoms: Orange brown spots appear on the leaves. This is an algal parasite. Conidia are hyaline. Leveillula taurica produces oidiopsis type of conidia Differentiate 1. Phytophthora capsici infects __________ and _________ crops True or False 1. Fungus: Colletotrichum gloeosporioides. Blister blight .Ex. No. COFFEE. COCONUT AND ARECANUT TEA 1. 11 Date: DISEASES OF TEA. 2. Fungus: Exobasidium vexans. Grey blight Symptoms: The disease appears as minute. They are hyaline. The disease attacks first flush of 2 to 3 young leaves and kills the young shoots and buds. Barks are killed in patches. The spots are mostly irregular and several of them may coalesce to form irregular patches. The first visible symptom is circular. Mycelium is septate. Acervuli are globose. The spots have fine concentric lines. sub-epidermal erumpent and dehisce rupturing epidermis by a pore. Leaves become curled and distorted. The circular spot gradually enlarges to 3 to13 mm dia.Symptoms: It is a disease in the nursery and planted crop. Pink tissues become white when they become old. Matured leaves are less affected. The pink concentrations crack into smaller fractions at right angles. The disease occurs in the nursery when the stem is 15 cm in height. straight or slightly curved. Young branches on the outside of the bush lose their leaves and die-back. which soon turn grey. They are generally confined to lower or more shaded side of branches. Fungus: Pestalotiopsis theae. oily. Conidiophores are hyaline and cylindrical. translucent spot on the tender leaf and later it turns into deep red shiny blisters. bulged on the under surface of the leaf with concave trough-like depression on the upper surface forming a classic blistered lesion. Basidia are long. conidia and basidiospores. Conidia are cylindrical and 5-celled with 3 filiform setulae. The fungus forms pink fructifications over affected stems. The conidia are borne singly at the tips of long stalks. yellowish.. It produces two kinds of spores viz. elliptical. They are not found on the leaves. 3. Fungus: Corticium salmonicolor (Pellicularia salmonicolor) . The basidiospores are ovate or oblong and hyaline. Pink disease Symptoms: Number of fine silky threads united into a thin film appears on the stem. The fungus attacks plucking points and causes die-back. Repeated attacks cause death of seedlings. Acervuli appear as black dots in the older spots on the upper surface. brown spots on older leaves. club-shaped and thin walled. Before the leaves turn black the lower surface assumes a white powdery appearance. parasiticus. Fungus: Capnodium spp. stem. dusty. branches and shoot of tea plants. Red rust Symptoms: Small translucent watery spots appear on the leaves. 6. The affected leaves are shed. Berries from diseased plants remain small.4. Infection on new stem reduces vigour or causes death. Sooty mould Symptoms: A black superficial fungal growth (mycelium and spores) is seen on the leaf. theae. On the under surface it is purple red and it becomes grey brown when old. They coalesce to form dark brown patches. Alga: Cephaleuros mycoidea and C. In severe cases complete defoliation is seen. they become purple red and then black with a purple margin. The disease reduces photosynthetic activity of the plant. powdery growth of uredospores. Small dark-brown irregular spots appear on the leaves. Leaf rust Symptoms: Small. Spots later turn into orange yellow colour. Fungi: Corticium invisum and C. Diseased leaves fall off. The convex surface is echinulated and the concave . On the upper surface of the leaves. The infection is superficial and associated with the presence of scale insects and aphids. which are orange-segment shaped. yellow translucent oily spots appear on upper surface of the young leaves. which eventually cover the whole leaf. The corresponding lower surface is covered with orange brown. COFFEE 1. Fungus: Hemileia vastatrix. 5. Black rot Symptoms: The disease appears normally at the end of May or early June. The dusty powder consists of uredospores. Spots enlarge into round shape of 10 to 15 mm in dia. The skin of the fruits becomes dry and hard. Fungus: Capnodium braziliense. stem and berries are covered with a black fungal growth (mycelium and spores) resulting in reduced photosynthetic activity. twigs and berries change into black colour (Black rot). Elongated brown or black lesions are seen on the branches. spreading web of fungal mycelium. Pellicularia koleroga). Basidiospores are hyaline and thin-walled. twigs and berries. Berries fail to mature and form kattekai. making it difficult to pulp. hyaline and 2 or 3 4. The fungus feeds on the secretions of these insects. Brown eye spot / Berry blotch Symptoms: Disease is severe on nursery seedlings and young crop. 5. Cercospora coffeicola. which arise in groups of 4 or 5 on short branches. Spots on berries are black and irregular. which result in blackening of twigs and dying from tip downwards. . Conidia are sub-cylindrical. Fungus: septate. Glomerella cingulata). hyaline. Leaves and berries become brown and finally black. 3. The under surface of the affected leaves is covered by a thin. Acervuli producing single celled conidia are noticed. Teleutospores are thick walled. Aecial and pycnial stages are not noticed. Fungus: Colletotrichum coffeanun (Syn. Fungus: Corticium koleroge (Syn. Spots on leaf are black and necrotic and have dark margin and grey centre and are surrounded by yellow haloes. profusely branched with numerous basidia. Koleroga / Black rot Symptoms: Affected leaves. They shrink and fall off.surface is and smooth. Mycelium is hyaline. Wherever heavy attack of aphids and scale insects are found sooty mould occurs. septate. Anthracnose / Nilgiri twig disease Symptoms: Greyish spots are observed on leaves. 2. Sooty mould Symptoms: Leaves. smooth and turnip-shaped. Berries turn dark brown or black with irregular sunken blotch with a purple halo. On the leaves and branches spots are necrotic. branches with frequent clamp connections. It is corky at first and become woody later.. leaves. c. In diseased palms in the advanced phase or in dead palms the fructifications of the fungus can be observed at the base of the tree just above the ground level as a bracket. Outer leaves fall off.COCONUT 1. Stem: The first visible symptom of the disease is found on the basal portion of the stem. stem. b. usually lateral and sometimes sessile. water content. Leaves: In the diseased palms the leaflets in the outer one or two whorls show yellowing and drooping. The quality of kernels from such bunches is poor. As the leaves of diseased palms droop down. Fungus: Ganoderma lucidum. up to three metres. Mycelium is hyaline. Inflorescence and nuts: Development of flowers is arrested and button shedding is common. The spindles become short and do not unfold properly. only very few normal nuts are produced. Roots: Decay and death of finer roots ( 70 %) proceeds bleeding symptoms in the stem. Chlamydospores are ellipsoid and slightly thick-walled. nut and kernel weight . the remaining leaves droop down in quick succession leaving the spindle leaf alone. the bark of the stem peels off. d. Diseased palm show exudation of reddish brown. Fruit bodies upto 30 cm size occur. Basal stem rot Symptoms: The diseased trees show the following typical symptoms in different parts of the palm viz. In severely diseased palms. thin-walled. Nuts are barren. In advanced stages the basal portion of the stem decays completely. Production of new roots in a diseased palm is very poor. viscous liquid from the basal portion of the stem. The fruit body is perennial. the subtended bunches hang down. Hymenial surface is white . Delayed production of new leaves and reduction in the size of leaves are the other symptoms. a. In some trees. stipitate. When the disease progress is slow. inflorescence and roots. Some palms show wilting symptoms without external bleeding. In advanced stages of infection. Most of the coconut trees bear profusely just prior to and at the time of initiation of symptoms. They may be terminal or intercalary and sometimes found in chains. Discolouration of the stem and internal rotting are commonly noticed up to the height of bleeding (exudation). copra weight and oil content decrease. Later it becomes brown. Stem bleeding Symptoms: The characteristic symptom of the disease is the exudation of a dark reddish brown fluid from cracks in the outer tissue of the stem. these patches coalesce resulting in a general decay. The infection may occur anywhere on the trunk but is rarely observed on the soft portion immediately below the crown. Matured endoconidia are hyaline to . The young leaves lose colour and droop before the heart leaf breaks down. Basidiospores are thick-walled. minutely verrucose and truncate at one end. The fluid turns black as it dries up on the bark. the decay of the internal tissue is localized but as the disease progresses. Chlamydospores are 30 to 40 mm in dia. 2. The affected heart leaf comes off easily when it is pulled. At the base of these young leaves brown sunken spots develop affecting a long strip of leaf tissue. The infected trees are not killed generally but their yield is reduced. browning and breaking down of the heart leaf or central shoot. The softer infected portion will be rotten and degenerated to slimy mass emitting foul smell. Oospores are 30 mm in size. In the early stages. When the growing bud is affected the tree is killed. Conidiophores are slender. brown. 3. The zoospores are biflagellate and motile. When rotting extends downward the surrounding whorl become dull yellow. Fungus: Phytophthora palmivora. Pores are small and round. The hyphae are intercellular. Bud rot Symptoms: Primary symptoms consist of pale colour. T. arising laterally from the hyphae and produce cylindrical endoconidia.or cream at first and turn brown later.(Thielaviopsis paradoxa). But young trees are severely infected. The tissues beneath the bleeding patches decay and become yellow. Fungus: Ceratostomella paradoxa. The period taken for withering of heart leaf depends on the point of infection and relative humidity. bending over. On young palms the spread of the disease is more rapid. The symptoms exhibited by young trees are different. Trees of all ages are affected. The base of the sporangium is usually rounded and attached with the sporangiophore almost at right angle. The external patches do not indicate the extent of the internal decay.paradoxa produces pale brown to brown hyphae. papillate and with a short pedicel. The trees may become very thin at the top and they are likely to be broken by wind. Sporangia are ovoid with the widest part near the base. Young nuts cease to develop and fall off prematurely. 4. The perithecial stage is Ceratostomella (=Ceratocysis) paradoxa. On the upper leaf surface globose or rectangular or ovoid. Ascospores are ellipsoid with unequally curved sides. Affected nuts are lighter in weight. At first minute yellow spots encircled by a greyish band are seen on the leaflets. In advanced stages. the tips and the margins and at times the whole leaflets dry and shrivel giving the leaf a burnt appearance. zinc. Chlamydospores are terminal in chains. Mahali disease / Fruit rot Symptoms: Characteristic symptoms include rotting and excessive shedding of immature nuts from the trees. iron. ARECANUT 1. Sporangia are pear-shaped. Conidiophores are cylindric to ovoid. The fungus produces acervuli. Apical cell tapering. non-septate and smooth. Grey leaf spot / Blight Symptoms: The disease symptoms develop on the outer whorl of leaves. copper and molybdenum. Gradually the centre of these spots turn greyish white with brown margin. Cause: Pencil point disease is caused due to micronutrients deficiency like boron. The stem tapers gradually and small crown fails to produce new leaves and trunk remains barren like a pointed pencil.pale brown and smooth walled. Fruit stalks and rachis of inflorescence are also affected. thickwalled and brown. Conidia are 5-celled straight or curved. The three median cells are coloured and the terminal cells are hyaline. Perithecia are partly immersed and light brown. Infected nuts lose their lustre. black. The lesions gradually spread and cover the entire nut which later rot and shed from the bunches. They increase up to 5 cm. arecae. hyaline. single celled and papillate. manganese. Several such spots coalesce into irregular and grey necrotic patches. deteriorate and become unsuitable for chewing. minute. White mycelial mat develops on the fallen nuts. The first visible symptom appears as water-soaked lesions on the surface of affected nuts. 5. Fungus: Pestalotiopsis (= Pestalotia) palmarum. Perithecia are ostiolate. crowned with three setulae. . Pencil point Symptoms: Affected trees produce a fewer small leaves with yellowing. Fungus: Phytophthora arecae var. acervuli are formed. oval. Stem bleeding Symptoms: During initial stages. Fungus: Thielaviopsis paradoxa. The fungus produces conidia which are single celled. Hollowness develop inside the stem upto varying depths. 3. The base of the stem shows brown discolouration and oozing of dark fluid. discoloured and dried. Blister blight and grey blight of tea . Later the spots coalesce and cracks develop on the stem. small. Anabe roga / Foot rot Symptoms: The first symptom is slight discolouration of the leaflets in the outer whorl of the leaves. Crowns of affected palms get reduced in size followed by reduction in yield. On cutting open the affected trunk.2. The fungus forms hard leathery brackets with brown polished upper surface and dirty white lower surface with numerous pores. The infected stem is easily broken off during heavy wind. cylindrical. Affected female flowers are shed. straight with obtuse ends with one or two oil globules. The inflorescence die-back in severe infection. Conidia in mass looks pink. This pale discolouration spreads to the whole leaf and the entire crown becomes yellow with the outer whorl drooping down and covering the stem. Fungus: Colletotrichum gloeosporioides. dark brown discolouration of internal tissues upto one metre from the ground level can be seen. Later the leaves in the inner whorl also become yellow. Finally a dark brown liquid oozes out from the cracks. 4. Subsequently the leaves dry up. subhyaline. Embryo of female flowers is attacked which shrivel up and show brown discolouration. Development of the inflorescence and nuts is arrested. Bracket-shaped fructification of the fungus called anabe appears at the base of the trunk. Fungus: Ganoderma lucidum. Differentiate 1. droop and fall off leaving the base stem. Inflorescence die-back and button shedding Symptoms: The disease appears on the rachillae of the male flowers and then on the main rachis as brown patches which soon spread from tip downwards covering the entire rachis and cause wilting. discoloured depressions appear on the basal portion of the stem. Roots of affected palms are brittle. Infected palms exhibit symptoms similar to drought. Affected young leaves curl and are distorted. Raised. Basal stem rot and Bud rot of coconut 4. The fungus produces cleistothecia with myceloid appendages. purple to red blotches are seen on immature wood of first-year canes. Fungus: Sphaerotheca pannosa var. Each cleistothecium (ascocarp) contains only one large ascus.2. (The fungus is of Oidium type). Conidia are oval-shaped and are produced in chains (5 to 10) on short. prematurely leaving the canes almost completely defoliated. 12 DISEASES OF FLOWER Date: CROPS (Rose. Spots are more or less circular with fringed margin. Affected leaves become yellow and fall off. Mahali disease and Anabe roga of arecanut Ex. Jasmine. 3. Crossandra and Chrysanthemum) ROSE 1. Fungus: Diplocarpon rosae. Yellow halo is present around matured spots. Diseased flower buds may not open and dry later. Older leaves show usually little distortion. white and sends globose haustoria into epidermal cell. The fungus produces ascospores in tiny apothecia and Marssonina type conidia in acervuli. 2. Asci are subglobose and each ascus contains eight ascospores. Coffee leaf rust and red rust of tea 3. Mycelium is septate. Young shoots and flower buds are also infected. Black spot Symptoms: Characteristic black spots appear on the leaves. The disease passes from the branch / twig to the main stem and from . Die-back Symptoms: Pruned twigs of the bushes show drying from tip downwards and become black. Black colour of the spot is prominently seen on the upper leaf surface. erect conidiophores. No. Ascospores are spherical. Powdery mildew Symptoms: Raised blister-like areas with greyish white powdery growth are seen on the leaves. rosae. Basal stem rot and stem bleeding of coconut 5. Mycelium is septate and dark coloured. The fungus produces pycnidia and pycnidiospores. Fungus: Diplodia rosarum. It produces orange pustules predominantly on lower surface. Stem and roots show browning of the internal tissues. Infected plant parts are hypertrophied. obclavate-cylindrical. Fungus: Fusarium solani 2. Diseased leaves turn yellow and fall prematurely. Top leaves wilt and bottom leaves show yellowing. Leaf spot Symptoms: Dark brown. Fusarium wilt Symptoms: Plants of all age are attacked and wilt occurs in patches. Rust Symptoms: It attacks all aerial parts and cause blisters or tumours. 6 to 8 celled with a pointed papilla. 3. Aeciospores are orange yellow. Fungus: Cercospora jasminicola. echinulate. cylindrical. Oval and orange cankers are seen on stems and twigs. straight to mildly curved. Spots join together to form bigger lesions. Flower buds are swollen. ellipsoid or ovate. orange-yellow and stalked. irregular spots appear on the leaf surface. Fungus: Phragmidium mucronatum. Yellowing spreads upward resulting in death of the plant. The conidia are septate and pale to olivaceous. Minute black hair-like tufts are produced on the under surface of the leaves (telial stage). Rust Symptoms: Orange to lemon yellow coloured pustules are seen on the under surface of the leaves which later turn to brick red in colour (uredial stage). In severe cases leaves become yellow and defoliate. 4. JASMINE 1. The base of the conidia is obconically truncate and its tip is subobtuse. Elongated and light brown lesions are found on the leaf stalks. Roots show black discolouration.there to the roots killing the whole plant. Teliospores are dark. Bushes are weakened and may die-back. Uredospores are single celled. deformed . The leaves droop. Fungus: Macrophomina phaseolina. Phyllody Symptoms: Clustering of the leaves and bushy appearance of the plants are the characteristic symptoms. dry and the plant dies. leafy and malformed flowers are seen. Bacterial leaf spot Symptoms: Yellowish green water-soaked. jasmini. irregular spots are seen on the leaves. Flower production is highly reduced. . Pratylenchus delatreii. Fungus: Xanthomonas campestris pv. Splitting of barks in branches subsequently lead to its death. The disease is associated with the root lesion nematode. Mycelium is hyaline and septate. It is an autoecious rust. 4. Drooping of leaves and wilting of plants are noticed. In the place of flowers. The sclerotia are brown to black and spherical to irregular in shape. 5. Root rot Symptoms: Sudden wilting of plants in patches is noticed. Fungus: Uromyces hobsonii. The leaves become linear and small and are closely arranged. Microconidia. Wilt Symptoms: The disease is noticed in plants one month after transplanting. Causal agent: Phytoplasma. macroconidia and chlamydospores are produced. Initially leaves turn pale green or yellow and later change into pink colour. The roots rot. Vector: Dialeurodes kirkaldii (Whitefly) CROSSANDARA 1. The mycelium is dark coloured and septate. Fungus: Fusarium solani. Young and old leaves both in bushy and climber type are affected. green.and do not open. 2. Defoliation and thereby stunting are also observed. bark shreds and decay and show large number of sclerotia. Each spot is surrounded by yellow halo. filiform. Pycnidia are numerous. It is transmitted through sap and through knives or tools during cultural operations. Fungus: Chrysanthemum stunt viroid (ChSV). straight or flexuous. 2. 4. Flowers from diseased plants open 7 – 10 days earlier than flowers from healthy plant. Some flowers may appear bleached and inferior in quality. Causal agent: Chrysanthemum aspermy virus. oftern curved or worm-like. sub-epidermal. Circular to irregular spots appear on leaves. chrysanthemi Powdery mildew – Erysiphe cichoracearum and Oidium chrysanthemi . Line pattern with diffused chlorotic mottling appear on the new leaves. dark. Conidia are hyaline. Axillary buds often grow prematurely and produce excess number of branches and stolons. Minor diseases Cercospora leaf spot – Cercospora chrysanthemi Alternaria leaf spot and blossom blight – Alternaria tenuis and A. Stunt Symptoms: Plants and flowers are smaller and paler. They coalesce with one another and form large patches covering major portion of the leaf. Fungus: Septoria chrysanthemella. The dead leaves hang on the stem for sometime. the leaves remain small and curl. The aphids spread aspermy disease 3. In severe infection.CHRYSANTHEMUM 1. The central disc florets remain green and stunted. Blotch / Leaf spot Symptoms: Blackish-brown. transversely septate (1-4 septate). Aspermy Symptoms: Mild mosaic mottling with marked distortion of the flowers. The flowers borne on the diseased plants are small in size and are distorted with irregular curllings and waviness of the ray florets. globose and ostiolate. Cuttings from diseased plants root poorly. No. How the powdery mildew of rose survives and spread? Differentiate 1. Wilt and root rot of crossandra Ex. Anamorph of Diplocarpon rosae is _______________ 2. 13 Date: FIELD VISIT . Sphaerotheca pannosa var rosae produces __________ type of conidia 3.Rust – Puccinia chrysanthemi Questions to be answered 1. . Wiregauge. Blender. knife Sieves. Conical flask. soil auger or hand hoe. No. Sampling from vegetable crops Select 6 rows of a field (2 from the beginning. Sampling from field crops Leave about 1m peripheral area of the field Remove 2-3 cm top soil Collect 200 cc soil along with feeder roots up to a depth of 15-20 cm (subsample) Collect 10 subsamples from one-hectare area in a zigzag manner Put all the subsamples in a polythene bag (composite sample) Label the sample properly and tie it with a rubber band 2. pencil. Centrifuge. 2 from the middle and 2 from the far end of the field) Collect 10 subsamples up to a depth of 20-30 cm from each pair of rows in zigzag manner Put all the subsamples in a polythene bag Label and tie the sample 3. Sampling from an orchard Take a sample from a tree up to a depth of 30-60 cm (feeder root zone) Collect subsamples from 10 trees randomly from one hectare area Pool all the subsamples in a polythene bag . rubber band. Methods of sampling 1. label. Sugar. polythene bag.Ex. Filter paper. Petridish. Lactophenol and Acidfuchion Lactophenol. 14 Date: SAMPLING AND EXTRACTION OF NEMATODES Objective To estimate plant-parasitic nematode population in a particular crop/field Materials required Trowel. shovel. Fendwickcan. Sampling from a tree Collect 5 subsamples each from around the trunk and drip line of the tree Put all the subsamples in a polythene bag Label and tie the sample Labeling Samples taken in polythene bag should be labeled with the following details. Extraction of nematodes from soil samples Objective To extract nematodes and cysts from soil sample for identification. i Location ii Host/crop and stage of crop iii Variety iv Previous crop v Date of sampling vi Soil type vii Name of the collector Important precautions Select live plants showing symptoms Take samples from the rhizosphere Avoid sampling immediately after fertilizer or pesticide application and irrigation or heavy rainfall Avoid surface soil pebbles and plant debris Keep the plant materials moist in polythene bags Storage of samples Samples should be processed immediately after collection for precise results. the samples can be stored in a refrigerator at 5ºC for about a week. Label and tie the sample 4. If immediate processing is not possible. counting and assessing their population density . 100 and 200-mesh sieves separately in beakers and label it Pass the contents again through a 350-mesh sieve discarding the filtrate Collect the residue left over 350-mesh sieve in a beaker and label it Examine the contents of beakers labeled as 60 for cyst nematodes and process 100.1. 100 and 200-mesh sieves (mesh: number of apertures/linear inch) Collect the residues left over 60. wait for a few seconds and pour it through a series of 60. 200 and 350-mesh residues further for separating nematodes 2. Cobb’s decanting and sieving method Principle The soil particles and nematodes settle at different rates due to differences in their specific gravity Different sized nematodes are retained on sieves of different pore sizes Procedure Mix thoroughly the composite soil sample and take 250 cc in a pan I Add about one litre water and stir well breaking clods and clumps Wait for 10-20 sec and pass this suspension to pan II through a 20-mesh sieve leaving heavy soil particles in the pan I Add one litre water to pan I and repeat the same process Collect the filtrate in pan II and roots in a beaker discarding the remaining materials Stir the suspension of pan II gently. Baermann’s funnel method Principle The active and motile nematodes tend to move towards water surface through tissue paper and get collected at the base of rubber tube due to gravitational force whereas inert soil particles and debris remain on the tissue paper Procedure Process the soil sample by Cobb’s decanting and sieving technique Take a glass funnel of 10 cm diameter attached with a short rubber tube to the stem and closed at the other end with a Hoffman’s clip and place the funnel on a suitable support Fill the funnel assembly with water carefully . 05) Procedure Process the soil sample by Cobb’s decanting and sieving technique and collect the suspension in a beaker Distribute the suspension into the centrifugal tubes equally and add water. Place double layers of tissue paper over a wire gauze (mesh) and place it on the funnel Allow the nematode suspension to settle. Sugar Floatation Technique Principle The difference in specific gravity of nematodes and sugar solution results in the separation of nematodes using the centrifugation (Specific gravity of sugar solution = 1. if necessary. by releasing the Hoffman’s clip Advantages Clear nematode suspension free of debris can be obtained Nematodes can be collected in a small amount of water Disadvantages Time consumed is more Nematodes may loose their activity due to lack of oxygen Sedentary and slow moving nematodes cannot be extracted 2a. 3.18. pour the remaining suspension on to the tissue paper set up Add water in such a way that the lower surface of the wire gauze touches the water Collect the nematode suspension carefully after 24-48 h. Modified Baermann’s funnel technique A Petri dish is used in this technique. to bring the level equally in the tube to 0.5 cm from the top Centrifuge at 3500 rpm for three minutes Discard the supernatant solution and retain the soil residue containing nematodes . instead of funnel in the Baermann’s funnel technique and the nematodes get collected in Petri dish. decant the supernatant. nematodes = 1. Fill half of the tubes with sugar solution of 1.18 specific gravity, shake well and fill again with the sugar solution up to 0.5 cm from the top (For preparation of sugar solution of 1.18 specific gravity, dissolve 484g sugar in water and make up the volume to one litre and add 10% lactic acid in water to inhibit the bacterial and mould growth) Centrifuge at 3500 rpm for one minute Decant the supernatant suspension from each tube through 350-mesh sieve Never leave nematodes in sugar solution for longer time and so wash the residues on the sieves repeatedly to remove the sugar solution Transfer the residues on the sieve to a beaker for observation Extraction of cysts 4. Conical flask method Principle Dry cysts lighter in weight will float in water and adhere to the sides of the container due to surface tension Procedure Collect the soil sample and shade dry Transfer a known quantity of soil into a conical flask, add water and shake well Add water up to the rim of the conical flask and leave it for 10 minutes Cysts will float and get collected in the rim Place a filter paper over a beaker and pour the suspension into it Cysts will be retained in the filter paper Allow the filter paper to dry and examine under microscope 5. Fenwick can method Principle Dry cysts lighter in weight will float in water and adhere to the sides of the container due to surface tension Procedure Fill the Fenwick can with water and place the dry sample in the 20 mesh sieve (Fenwick can is a brass can having a broad inclined base and narrow neck provided with a 20-mesh sieve over a funnel. Outside the neck of the can, a collar is attached with 60-mesh sieve to drain water. The can is provided with a drain plug at the bottom) Wash the shade dried sample with water into the apparatus Cysts will pass on to the collar region and get collected in 60-mesh sieve Allow the water to drain Wash the contents of the sieve into a white enamel basin Collect the floating cysts in periphery of the basin Extraction of nematodes from root samples Objective To extract nematodes from plant parts for identification and estimation of population Methods 1. Direct examination Procedure Wash the infested plant material thoroughly and chop into small pieces Put this material in a Petri dish containing water Migratory and endo/semi endoparasitic nematodes that come out of the chopped material and move into water can be seen directly under microscope Alternatively the chopped material can be processed by modified Baermann’s funnel technique 2. Root incubation method Principle The nematodes migrate out of the roots due to suffocation Procedure Wash the roots to remove the adhering soil particles Place the longitudinally cut wet roots in half of the polythene bag/glass jar Seal the jar by screwing the lid with a few loose turns (do not tighten) or secure the polythene bag with rubber band Incubate at 15°C for 72 h Remove the nematodes, which have migrated out of the roots by flushing the roots with water for three times Pass the washed water through 350-mesh sieve and collect the residue into a beaker with little water 3. Blender technique or Mechanical maceration or Homogenizer or Disintegrator technique Principle On maceration of the infested roots, the nematodes get separated from the root tissues because of mechanical force Procedure Wash the roots with water to remove adhering soil particles Chop the roots to 0.5-1.0 cm pieces and transfer them to a blender containing about 100 ml water (up to blade level) Run the blender for 15 sec (30-60 sec for aged/hard roots) Pour the resultant mixture into 60-mesh sieve followed by 350-mesh sieve and wash gently with a stream of water Discard root residues in 60-mesh sieve and collect the nematode suspension on 350-mesh sieve in a beaker Transfer the nematode suspension into modified Baermann’s funnel 4. Observation of Endo and Semiendo parasitic nematodes in situ Wash the roots with water to remove the soil particles Cut the roots into 1 cm bits Plunge root bits of 1cm length in a test tube with boiling acid fuchsin lactophenol and heat it over a flame (to prepare acid fuchsin lactophenol, dissolve one gram of acid fuchsin stain in 100ml of distilled water and take 5 ml of this solution in 100 ml of lacto phenol) Drain the excess stain and wash the stained roots with water Submerge the roots in plain lactophenol in a Petri dish and leave it over night Ex. No. 15 Date: GENERAL MORPHOLOGY OF PLANT PARASITIC NEMATODES Objective: To differentiate plant parasitic nematodes from free living nematodes To differentiate males, females and juveniles To study the important morphological features of plant parasitic nematodes without annulation : Typically long. arcuate. Saprophyte (free living) Parasite Stylet is present Slow in movement Stylet is absent Comparatively faster in movement Examine the nematodes under various magnifications of a compound microscope and stereomicroscope and note the following characters. groundnut Morphology Body Stylet : Typically long (5.short. guiding ring in the posterior part of the spear . Xiphinema Major hosts : Rose.well developed.5mm in length). well developed with anteriorly projecting basal knobs Oesophagus: Well developed with dorsally overlapping gland lobe Female : Vulva . cotton Morphology Body : Medium. Morphology of Order – Tylenchida Lance nematode. slightly curved ventrally when relaxed (open ‘C’ shaped) Head : High. rounded with massive sclerotization having cap like lip Stylet : Massive. spicules . tail . amphidelphic.Procedure Examine the given specimens under microscope and identify them with the following characters. very slender with typical flanges.2 mm in length. slender. set off. bursa extending to tail tip Morphology of Order – Dorylaimida Dagger nematode.50-60%. 1 . citrus. bluntly rounded Male : Tail . 40–50 µm long. ovaries – didelphic. Hoplolaimus Major hosts : Sugarcane.short. pointed. Male: spicules prominent. ovary . tail – tapering to rounded. abutting basal glands Female : Vulva .near the middle of the body or near posterior end of oesophagus when only one ovary is present. lip region typically continuous with body Stylet : Usually strong with large basal knobs Oesophagus : Typical with well developed median bulb. sweet potato Body : Medium. 0. vegetables.2 mm in length. Morphology Body : 0. conical. bursa extending to tail tip B. sclerotization moderate Stylet : Well developed. ovaries – didelphic. tail – short. spiral when relaxed Head : Conoid to round. amphidelphic.near middle of body. arcuate Identification of nematodes A. long. ovary – mono or didelphic. potato. spicules well developed with bursa reaching tail tip . amphidelphic.60–70%. dorsally round to nearly pointed convex to conoid or hemispherical with short projection on ventral side Male : Short.Oesophagus : With slender anterior tube and wide posterior part (bottle shaped) Tail : Bluntly rounded with projection on ventral side in both male and females Female : Vulva . posterior branch rarely reduced and non–functional. usually fully developed. Stunt nematode. Helicotylenchus Major hosts : Banana.5 to 1.didelphic.elongate. maize. spicules slightly curved.6 – 1.4 mm in length. 3-4 times the lip width with rounded or cup shaped knobs Oesophagus: Gland lobe overlapping ventrally Female : Vulva . small grains. 2-3 times the anal body diameter Male : Tail . Spiral nematode. Tylenchorhynchus Major hosts Morphology : Tobacco. maize.short. Root lesion nematode. flattened. Ring nematode.8 mm in length. cuticle provided with 42-200 prominent. retrose annules Stylet : Typical. short.monodelphic. annules of male are much smaller.8 mm). banana Morphology Body Head : Small. males with degenerated oesophagus Female : Vulva . external layer marked by fewer annules.3-0. Pratylenchus Major hosts : Coffee. glands forming small posterior bulb. crossandra. Ring nematode. wide with large annules in female and juveniles. strongly sclerotized . vines Morphology Body : Length typically short (0. 0.conoid. extending anteriorly Male : Tail – pointed. 0. vines Morphology Body : Straight. cuticle with two detached layers. males without forwardly directed knobs Oesophagus : With a strong median bulb which is fused with the procarpus. slightly curved. spicule . medium with anteriorly directed process. Criconemoides Major hosts : Perennial fruits.prominent. ovary – monodelphic Male : Tail . spicules .5 mm long. annules . but not retrose Stylet : Strong. Hemicriconemoides Major hosts : Perennial fruit trees. bursa weakly present D.C. slightly curved ventrally when relaxed : Low. ovary .4-0. long with anteriorly directed knobs Oesophagus : With strong median bulb fused with the procorpus Female : Vulva – posterior. stout.present. bursa weakly developed/absent E.near posterior part of the body. stylet – medium with round basal knob. tail – subcylindrical or conoid : Tail . ovaries – didelphic. Tylenchulus semipenetrans Major host : Citrus (host specific) Morphology Immature female Vermiform. straight or ventrally arcuate when relaxed Stylet : Strongly developed. sclerotization weak.Oesophagus: Median bulb well developed. oesophageal gland lobes overlapping ventrally Female : Vulva – posterior (80-85%). oesophagus – strong but median bulb not well separated from procorpus. ovary – monodelphic. arcuate. ovary – monodelphic. vulva and excretory pore – very posterior. vulva – very posterior.slender. Citrus nematode. round.short. anteriorly outstretched. tail – conical. bursa extending to tail tip Male F. no anus or rectum Mature female Anterior part – slender. pointed Juvenile . dorsally convex to conoid. tail – conical. arcuate. lobe overlapping on ventral side Female Male : Vulva – median. no anus or rectum Male Vermiform. small (<0. 1. posterior part – swollen with thick cuticle and projecting tail.slender. Hirschmanniella Major host : Rice (host specific) Morphology: Body : Long. tail – elongate. head . irregular with thin cuticle. prodelphic with post uterine sac. Rice root nematode. conoid with terminal mucron : Tail – elongate. spicules .5 mm). ovary – monodelphic. amphidelphic. spicules . cephalic sclerotization. stylet and oesophagus reduced. anterior.0 mm in length. convoluted. short and slender. bursa not reaching to tail tip G.continuous. typically short with rounded knobs Oesophagus : Elongated with conspicuous median bulb. spicule slightly curved.2-3. no bursa. excretory pore – slightly anterior to the vulva. Aphelenchoides besseyi Morphology Body Stylet : Slender. tail – long. Globodera Major host : Potato (host specific) Morphology Similar to Heterodera.3-0. Heterodera Important species and major hosts Sugarbeet cyst nematode – H. circular fenestra. spherical or rectangular in shape. Potato cyst nematode. genital primordium differently shaped in male and female juveniles H. male tail curls ventrally forming shape of a walking stick : With thickening at the base without knobs Oesophagus: Prominent median bulb.0mm in length) and juveniles (0. gubernaculum present. Cyst nematode. but the cyst is globose. typically swollen. . bursa absent I. avenae Rice cyst nematode – H. Rice white tip nematode. schachtii Cereal cyst nematode– H. more than 0. straight or ventrally arcuate when relaxed.Vermiform. cajani Morphology Body : Slender in males (1.6mm in length). vulva – subterminal near anus. J. 0. more or less occupying the body width.5-0. pointed. whitish first. lemon or globe shaped in females (0. vulva and anus located on terminal cone (vulval cone/cone top) with two translucent areas (fenestrae) on either side of vulval slit Male : Spicules near the posterior end. tanning to brownish black as the cysts mature. oryzicola Pigeonpea cyst nematode – H. lobe overlapping the intestine dorsally. vulval slit is surrounded by a single.6 mm in length.8mm in length) Stylet : Short in males with rounded basal knobs.02mm long in Juveniles Oesophagus: With well developed median bulb and lobe extending back and overlapping the intestine Female : Cuticle – thick. vulva and anus are not on a terminal cone.0–2. Caused by above ground feeders Dead or devitalized buds Nematodes.well developed. distorted and twisted. tail – medium. conoid. prodelphic. conoid. no bursa Ex.Aphelenchoides ritzemabosi . Chrysanthemum - Aphelenchoides ritzemabosi Crinkled and distorted stems and foliage The growing point or leaf infested with nematode is not killed.Ditylenchus dipsaci Coconut (red ring) . with or without mucron Male : Tail – medium. thorne shaped.Bursaphelenchus cocophilus Leaf lesions In dicot plants some foliar nematodes penetrate leaf tissue through stomata and feed on the parenchyma tissues causing leaf lesions. 16 Date: SYMPTOMS OF NEMATODE DAMAGE A. produce this symptom. Chrysanthemum (Leaf lesions) .Female : Vulva – posterior (60-75%). but continues to grow and hence the resultant stem or leaf is crinkled. Onion and garlic . Wheat - Anguina tritici Necrosis and discolouration Some nematodes live and feed within the tissues of stem and leaves causing varying degree of necrosis and discoloration. No. Paddy - Ditylenchus angustus on paddy Seed galls Nematode feeds on flower primordia and completes its life cycle and the infested flower primordium develops into gall containing large number of nematodes. ovary – monodelphic. which feed on vegetative and reproductive parts. spicules . Solanum elaegnifolium . Symptoms on above ground parts Yellowing Destruction of roots by nematode feeding leads to physiological changes and nutritional deficiency in plants.Ditylenchus phyllobia B. These are comparable to seed galls and they serve as structures in which the parasites mature and reproduce. the nematode infested plants can be seen in patches here and there due to random distribution of nematodes in the field. most of the nematode damage symptoms resemble the symptoms of nutritional disorder. Broad leaved plants like tobacco and brinjal – Meloidogyne incognita Patchy appearance Unlike nutrient deficiency.Leaf gall Nematodes that feed on leaves produce galls on the leaves of their host plants. Hence. It is called as day wilt. Yellowing in coffee – Pratylenchus coffeae Light green foliage in potato – Globodera rostochiensis Yellow or White tip in rice – Aphelenchoides besseyi Mottled leaves in orange – Tylenchulus semipenetrans Stunting/poor growth Wheat and barley Potato Peas – – Heterodera avenae Globodera rostochiensis – Meloidogyne incognita Day wilting Plants infested with the root knot nematodes tend to wilt in hot weather even though enough moisture is present in the soil. . Caused by below ground feeders Nematodes that feed on below ground parts produce symptoms both on below ground and above ground parts. Vegetables and banana . due to reinfestation. The primary galls are small but at later stage. The differences between nematode gall and bacterial nodule are as follows. Twisting of leaves and stem in rice - Ditylenchus angustus Twisting of basal leaves in onion - Ditylenchus dipsaci Symptoms on below ground parts Root galls Formation of galls on the roots is the typical symptom caused by Meloidogyne spp on various crops. Oat.Meloidogyne spp. larger galls are formed. Other nematodes also produce smaller galls but without the formation of giant cells. The galls are produced due to the formation of giant cells (syncytia). species of the nematode. The galls may vary in size and shape depending on the initial nematode population. galls produced by nematode differ from nodules produced by bacterium. Gall Swelling of root itself Can not be detached Hard Colour of the inner content unchanged Different size and shape Nodule Attached laterally on the side of the root Can be detached easily Soft Inner content is pinkish Uniform size and shape . rye and wheat - Ditylenchus radicicola Citrus - Hemicycliophora arenaria Rose - Xiphinema diversicaudatum Marygold - Longidorus sp.Vegetables – Meloidogyne incognita Potato – Globodera rostochiensis Malformations The affected foliar parts will be malformed. In leguminous plants. crop etc. The lesions lead to the formation of rotting or tunnels and cavities in the roots.Reduced root system Feeding of nematodes on root tip affects the root growth. These lesions are clearly visible by splitting the affected roots longitudinally. Corn - Belonolaimus longicaudatus Root proliferation Nematode attack on young roots stimulates the branching of rootlets near the region of invasion. The resultant root system is composed of numerous short stubby branches arranged in clusters giving a ‘stubby’ appearance. Tomato - Meloidogyne hapla Root lesion Migratory endoparasites. This symptom is called as coarse root system. produce elongate brown coloured necrotic lesions due to accumulation and oxidation of phenolic compounds on the feeding site. Rotting of roots in many crops . Sugarcane - Trichodorus sp. the main roots will be devoid of any rootlets. .Pratylenchus spp. which feed on root cortex or epidermis. Coarse root When the lateral roots are completely fed by nematodes. Cotton - Rotylenchulus reniformis Stubby root The lateral roots produce excessive rootlets. .Helicotylenchus multicinctus Fish hook The root tip will look bent upwards. Ditylenchus destructor on potato. Scutellonema bradys on yam.Radopholus similis Banana . Groundnut - M. Meloidogyne hapla on carrot.Cavities on roots in banana and Coconut . Forking of storage roots The root -knot nematode damage results in forking of storage roots and causes malformation thus reduces its market value. arenaria Potato - M. Malformation of tubers/pods Root-knot infestation results in malformation of below ground tubers/pods. incognita Rotting of fleshy parts The tubers are injured due to nematode feeding and this injury act as a predisposing agent for certain micro organisums and results in rotting of tubers. E.g. E. Onion - Xiphinema sp.g. TAMIL NADU AGRICULTURAL UNIVERSITY ANBIL DHARMALINGAM AGRICULTURAL COLLEGE & RESEARCH INSTITUTE NAVALUR KUTTAPPATTU. TIRUCHIRAPPALLI-620 009 . ___________________) of IV Semester during the academic year _____________________ for the course PAT 202. DISEASE AND NENATODE MANAGEMENT IN CROPS (2+1) COURSE TEACHERS EXTERNAL EXAMINER INTERNAL EXAMINER .D. No.CERTIFICATE Certified that this is the bonafide record of Selvan/ Selvi _________________________ (I. CONTENTS Name of the Student : Year : Batch : I. Diseases of pulses (Blackgram. No. pearlmillet and ragi) 3. Diseases of oilseeds (Groundnut. Date Title 1. grapes. gingelly. Diseases of rice and wheat 2. papaya. sapota and guava 7. : Academic Year : Semester : PAT 202. brinjal and bhendi Page No. banana. maize. pigeonpea and chickpea) 4.D. No. apple and peach 8. Diseases of citrus. Diseases of tomato. castor and sunflower) 5. Date of Sumission Grade / Remarks Signature of Teacher . greengram. Diseases of cotton and sugarcane 6. pomegranate. Diseases of millets (Sorghum. DISEASE AND NEMATODE MANAGEMENT IN CROPS (2+1) Ex. Diseases of mango. betelvine and pepper 11. coconut and arecanut 12. Identification of plant parasitic nematodes 16. Sampling and Extraction of Nematodes i ii Soil and root sampling Different methods extraction of iii Observation of Endo and Semiendo parasitic nematodes in situ 15. tapioca. garlic. coffee. crucifers. Symptoms of nematode damage . Order Tylenchida and Dorylaimida ii. Field visit 14. turmeric. Diseases of cucurbits. Diseases of tea. coriander. chillies. General morphology of plant parasitic nematodes i. potato. Diseases of flower crops (rose. and sugarbeet 10. crossandra and chrysanthemum) 13. Diseases of onion. ginger. jasmine.9.