Important Paddy Diseases

Disease symptomatology, pathogen biology and Management strategy of Sheath blight, Blast, Bacterial leaf blight and False smut of Paddy.

1. JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

2. LIST OF RICE DISEASES MAJOR FUNGAL DISEASES   Sr. No. Disease Causal Organism   1 Blast Pyriculria grisea   2 Brown spot Bipolaris oryzae   3 False smut Ustilaginoidea virens   4 Kernel smut Tilletia barclayana   5 Leaf smut Entyloma oryzae   6 Sheath blight Rhizoctonia solani   7 Sheath rot Sarocladium oryzae   8 Stem rot Sclerotium oryzae   MINOR FUNGAL DISEASES   9 Sheath spot Rhizoctonia oryza   10 Stackburn (Alternaria leaf spot) Alternaria padwickii   11 Stem rot Sclerotium oryzae   12 Water-mold Fusarium spp., Pythium spp.   13 Black kernel Curvularia lunata   14 Pecky rice (kernel spotting) Cochliobolus miyabeanus, Sarocladium sp.   15 Root rots Fusarium sp., Pythium sp   16 Seedling blight Fusarium sp., Curvularia sp.   BACTERIAL DISEASES 1 Bacterial blight Xanthomonas oryzae pv. oryzae 2 Bacterial leaf streak Xanthomonas oryzae pv. oryzicola 3 Foot rot Erwinia chrysanthemi 4 Grain rot Burkholderia glumae NEMATODE DISEASES 1 Rice cyst nematode Heterodera oryzae 2 Rice root nematode Hirschmanniella oryzae 3 Rice root-knot nematode Meloidogyne graminicola 4 White tip nematode Aphelenchoides oryzae VIRAL DISEASES 1 Rice tungro Rice tungro virus (RTSV, RTBV) 2 Rice grassy stunt Rice grassy stunt virus 3 Rice yellow dwarf Rice yellow dwarf virus 4 Rice ragged stunt Rice ragged stunt virus MAJOR FUNGAL DISEASES Sr. No. Disease Causal Organism 1. Blast Pyriculria grisea 2. Brown spot Bipolaris oryzae 3 . False smut Ustilaginoidea virens 4 . Kernel smut Tilletia barclayana 5 . Leaf smut Entyloma oryzae 6 . Sheath blight Rhizoctonia solani 7 . Sheath rot Sarocladium oryzae 8 . Stem rot Sclerotium oryzae MINOR FUNGAL DISEASES 9. Sheath spot Rhizoctonia oryza 10. Stackburn ( Alternaria leaf spot) Alternaria padwickii 11 . Stem rot Sclerotium oryzae 12 . Water-mold Fusarium spp., Pythium spp. 13 . Black kernel Curvularia lunata 14 . Pecky rice (kernel spotting) Cochliobolus miyabeanus , Sarocladium sp. 15 . Root rots Fusarium sp., Pythium sp 16 . Seedling blight Fusarium sp., Curvularia sp.

3. BACTERIAL DISEASES 1. Bacterial blight Xanthomonas oryzae pv. oryzae 2. Bacterial leaf streak Xanthomonas oryzae pv . oryzicola 3 . Foot rot Erwinia chrysanthemi 4 . Grain rot Burkholderia glumae NEMATODE DISEASES 1 . Rice cyst nematode Heterodera oryzae 2 . Rice root nematode Hirschmanniella oryzae 3 . Rice root-knot nematode Meloidogyne graminicola 4. White tip nematode Aphelenchoides oryzae VIRAL DISEASES 1 . Rice tungro Rice tungro virus (RTSV, RTBV) 2 . Rice grassy stunt Rice grassy stunt virus 3 . Rice yellow dwarf Rice yellow dwarf virus 4 . Rice ragged stunt Rice ragged stunt virus

4. BLAST BROWN SPOT blb RICE TUNGRO SHEATH ROT BAKANAE RAGGED STUNT FALSE SMUT SHEATH BLIGHT LEAF SCALD YELLOW DWARF GRASSY SHOOT GRAIN DISCOLOURATION SYMPTOMS OF RICE DISEASES AT FIELD LEVEL JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR , M.P . College of Agriculture, Balaghat , Dr . D.K . PANCHESHWAR

5. MAJOR RICE DISEASES AT BALAGHAT DISTT. Caused by fungus:  Rhizoctonia solani   ( Kühn ) ( Teleomorph :  Thanatephorus cucumeris   (A. B. Frank) Donk .) Rice sheath blight is one of the most economically significant rice diseases. This disease causes significant grain yield and quality losses. Yield losses of up to 50% have been reported under most conducive environments. Sheath blight is a soilborne disease. The fungus belongs to the phylum Basidiomycota , family Ceratobasidiaceae . SHEATH BLIGHT

6. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

7. Early symptoms usually develop on the leaf sheaths at or just above the water line as circular, oval or ellipsoid, water-soaked spots which are greenish-gray in color. As the disease progresses, they enlarge and tend to coalesce forming larger lesions with grayish white centers surrounded by tan to dark brown irregular borders or outlines. Infection can spread to leaf blades and cause irregular lesions with dark green, brown, or yellow-orange margins. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

8. Microscopic runner hyphae and pea-sized sclerotia are two signs of pathogen infection. The white, web-like hyphae (threads) of the fungus grow on the sheaths and leaves under favorable conditions and serve to spread the disease from leaf to leaf, causing infections of nearby plants Sclerotia of the fungus are formed in the infected sheaths and leaves most typically at the boot to heading stages Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

9. Disease cycle   Rhizoctonia solani  showing different phases of sclerotia development and disease symptom on rice Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

10. SPRAY ANY ONE FUNGICIDES 1. Difenoconazole 25% EC @ 100 ml/acre 2. Flusilazole 40% EC @ 125 ml/ acre 3. Hexaconazole 75 % WG @ 30 g/acre 4. Pencycuron 22.9% SC @ 300 ml/acre 5. Thifluzamide 24% SC @ 150 g/acre 6. Azoxystrobin 18.2% w/w + Difenoconazole 11.4% w/w SC @ 1ml/ litre 7. Azoxystrobin 7.1 % + Propiconazole 11.9 % w/w SE @ 200 ml/acre 8. Azoxystrobin 11% + Tebuconazole-18.3% SC W/W @ 304 ml/acre 9. Fluxapyroxad 62.5g/l FS + Epoxiconazole 62.5 g/L EC @ 250-300 ml/acre 10. Iprodione 25%+ Carbendazim 25% WP @ 200g/acre JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

11. RICE BLAST Caused by fungus: Pyricularia oryzae ( Teleomorph : Magnaporthe oryzae ) Rice blast can affect most of the rice plants with the exception of the roots. The fungus can infect plants at any growth stage. Symptoms can be either lesions or spots; their shape, colour and size, depending on varietal resistance, environmental conditions and the age of the lesions. The pathogen infects and produces lesions on the following parts of the rice plant: leaf (leaf blast), leaf collar (collar blast), culm , culm nodes, panicle neck node (neck rot) and panicle (panicle blast).

12. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

13. Rice leaves Symptoms on leaves may vary according to the environmental conditions & age of the plant, On susceptible cultivars, lesions may initially appear gray-green and water-soaked with a darker green border and they expand rapidly to several centimeters in length. On susceptible cultivars, older lesions often become light tan in color with necrotic borders. Rice collars Symptoms of infection of the collars consist of a general area of necrosis at the union of the two tissues. Collar infections can kill the entire leaf and may extend a few millimeters into and around the sheath. The fungus may produce spores on these lesions. JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

14. Rice necks Rice panicles Necks are often infected at the node by the rice blast fungus and infection leads to a condition called rotten neck or neck blast. Infection of the necks can be very destructive, causing failure of the seeds to fill (a condition called blanking) or causing the entire panicle to fall over as if rotted. The rice blast fungus can also infect the panicles as the seeds form. Lesions can be found on the panicle branches, spikes, and spikelets . The lesions are often gray brown discolorations of the branches of the panicle and over time, the branches may break at the lesion. Rice seeds . Symptoms of rice blast on seeds themselves consist of brown spots, blotches and occasionally the classic diamond-shaped lesion often seen on leaves. The process and the time during which infection of seeds by spores of the pathogen occurs has not been fully described but recent information shows that the fungus can infect seeds by infecting the florets as they mature into seeds, and it is believed that this is the main way seed infection develops . JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

15. Disease cycle Starts its infection cycle when a three celled conidium lands on rice surface. The spore attaches to hydrophobic cuticle and germinates Producing a narrow germ tube Flattens and hooks at its tips before differentiating into an appressorium Single celled appressorium matures and the three celled conidium collapses and dies in a programmed process that requires autophagy Appressorium becomes melanized and develops substantial turgor This translates into physical force and a narrow penetration at the base Puncturing the cuticle and allowing entry into the rice epidermis Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

16. SPRAY ANY ONE FUNGICIDES 1. Isoprothiolan 40% EC @ 300 ml/acre 2. Kitazin 48% EC @ 200 ml/acre 3. Kresoxim -methyl 44.3% SC @ 200 ml/acre 4. Picoxystrobin 22.52% w/w SC @ 250 ml/acre 5. Pyraclostrobin 100g/l CS @ 400 ml/acre 6. Tebuconazole 25% WG @ 300 g/acre 7. Kresoxim -methyl 40% + Hexaconazole 8% WG @ 200 g/acre 8. Tebuconazole 50% + Trifloxystrobin 25% WG @ 80g/acre 9. Tricyclazole 18.0% w/w + Tebuconazole 14.4% w/w SC @ 400ml/acre JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

17. Bacterial blight is one of the most serious diseases of rice. Yield loss due to bacterial blight can be as much as 70% when susceptible varieties are grown, in environments favorable to the disease. When plants are infected at booting stage, bacterial blight does not affect yield but results in poor quality grains and a high proportion of broken kernels. It causes wilting of seedlings and yellowing and drying of leaves. BACTERIAL LEAF BLIGHT Caused by : Xanthomonas oryzae   pv .  oryzae

18. When it occurs The disease is most likely to develop in areas that have weeds and stubbles of infected plants. It can occur in both tropical and temperate environments, particularly in irrigated and rain fed low land areas. In general, the disease favors temperatures at 25−34°C , with relative humidity above 70%.

19. Old lesions turn yellow to grayish white with black dots due to the growth of various saprophytic fungi. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

20. Old lesions turn yellow to grayish white with black dots due to the growth of various saprophytic fungi. On severely infected leaves, lesions may extend to the leaf sheath. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

21. On young lesions, bacterial ooze resembling a milky dew drop can be observed early in the morning. The bacterial ooze later on dries up and becomes small yellowish beads underneath the leaf. JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P. Dr . D.K . PANCHESHWAR

22. On older plants, lesions usually develop as water-soaked to yellow-orange stripes on leaf blades or leaf tips or on mechanically injured parts of leaves. Lesions have a wavy margin and progress toward the leaf base. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

23. To quickly diagnose bacterial blight on leaf Cut a young lesion across and place in a transparent glass container with clear water. After a few minutes, hold the container against light and observe for thick or turbid liquid coming from the cut end of the leaf.

24. Management of BLB Planting resistant varieties has been proven to be the most efficient, most reliable, and cheapest way to control bacterial blight. Use balanced amounts of plant nutrients, especially nitrogen. Ensure good drainage of fields (in conventionally flooded crops) and nurseries. Keep fields clean. Remove weed hosts and plow under rice stubble, straw, rice ratoons and volunteer seedlings, which can serve as hosts of bacteria. Allow fallow fields to dry in order to suppress disease agents in the soil and plant residues.

25. SPRAY ANY ONE BACTERI CIDES 1. COPPER HYDROXIDE 53.8% DF @ 3.0 g/ litre of water 2. Streptocycline (Streptomycin sulphate 90% + Tetracycline hydrochloride 10%) @ 2.0g/ litre of water 3. 2-bromo-2-nitropropane-1, 3-diol ( Bronopol 100%) @ 0.5 g/ litre of water JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

26. FALSE SMUT Caused by fungus: Ustilaginoidea viren Teleomorph : Claviceps oryzae-sativae False smut causes chalkiness of grains which leads to reduction in grain weight. It also reduces seed germination. The disease can occur in areas with high relative humidity (>90%) and temperature ranging from 25−35 ºC .   Rain, high humidity, and soils with high nitrogen content also favors disease development. Wind can spread the fungal spores from plant to plant. False smut is visible only after panicle exsertion . It can infect the plant during flowering stage .

27. Important of RFS The disease affects the early flowering stage of the rice crop when the ovary is destroyed. The second stage of infection occurs when the spikelet nearly reaches maturity . These causes chalkiness and can reduce 1,000-grain weight. It also causes a reduction in seed germination of up to 35%. In damp weather, the disease can be severe and losses can reach 75%.

28. Individual rice grain transformed into a mass of velvety spores or yellow fruiting bodies Growth of velvety spores enclose floral parts Immature spores slightly flattened, smooth, yellow, and covered by a membrane Growth of spores result to broken membrane Mature spores orange and turn yellowish green or greenish black Only few grains in a panicle are usually infected and the rest are normal Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

29. A, Typical symptom of rice false smut disease in the field. . B, An artificial  U. virens  inoculated panicle in green house. C, Formation of false smut balls which are first of all yellowish orange to green in color , and finally greenish-black. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

30. Smut ball bursts and becomes orange then later yellowish-green or greenish-black in color Infection usually occurs during the reproductive and ripening stages Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

31. Discolouration of Grains Grains Transformed into a Mass of Yellow Fruiting Bodies Greenish Black Smut Balls with a Velvetty Appearance Smut Balls Bursts and becomes Black in Color Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

32. Morphology of the RFS pathogen Colony of Ustilaginoidea virens ( anamorph ) in PSA medium from top view (A) and back view (B) (C) Colonies of U. virens in PSB. (D) A single colony of U. virens in PSB. (E) Conidia of U. virens in PSB. (F) Chlamydospores of U. virens from false smut balls. (G) Sclerotia of Villosiclava virens ( telemorph ). (H) Sclerotia of V. virens germinate to produce fruit bodies. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

33. Disease cycle of rice false smut RFS balls with chlamydospores and sclerotia are formed in rice spikelets (①), and overwinter in field (②). Next spring, spores in soil (③ ) and on contaminated rice grains (④) germinate and attack rice roots and coleoptiles when rice seeds are germinating. Hyphae grow intercellularly in roots and coleoptiles, but could not infect seedlings systemically. Instead, hyphae may grow epiphytically on leaf surface or leaf sheath, and reach the external surface between tiller buds at the late vegetative stage (⑤) or even the surface of elongated stems at the heading stage. It is possible that the pathogen hyphae reach the inner space of rice panicles and initiate infection at the late booting stage (⑥). Meanwhile, conidia produced by chlamydospores and/or ascospores from sclerotia (⑦) also initiate attack on rice spikelets in developing panicles (⑧). Spores could firstly germinate on the surface of a spikelet (⑨), and the hyphae extend into the inner space of the spikelet via the gap between the lemma and the palea (⑩). Stamen filaments are the major infection sites for the pathogen (⑪). After successful colonization in floral organs, a large amount of fungal mass are formed and eventually grow into a false smut ball (⑫) . co, coleoptile ; p, panicle; sp, spikelet; le, lemma; pa, palea ; sf , stamen filament; lo, lodicule ; ov , ovary; and fsb , false smut ball. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

34. SPRAY ANY ONE FUNGICIDES 1. Copper Hydroxide 77% WP @ 800 g for 300 litre water/acre 2. Fluopyram 17.7% w/w + Tebconazole 17.7% w/w SC @ 220 g/acre 3. Picoxystrobin 7.05% + Propiconazole 11.7% SC @ 400 ml/acre 4. Tricyclazole 20.4% w/w + Azoxystrobin 6.8% w/w SC @ 400 ml/acre 5. Tricyclazole 18.0% w/w + Tebuconazole 14.4% w/w SC @ 400 ml/acre JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

35. Summary of rice diseases management RESISTANCE (RiceTec hybrids) SEED QUALITY (all rice diseases) SEED TREATMENT (seedling diseases) SEEDING RATE (high favors most diseases) FLOOD (prevents leaf blast) NITROGEN (high favors most diseases – low favors NBLS ( Narrow Brown Leaf Spot ) and BS ( Brown spot ). POTASSIUM (low favors Sclerotium and brown spot) PLANTING DATE (late favors most diseases) FUNGICIDES (late booting for KS; late booting to heading for BS and NBLS; heading for neck blast)

36. As seed treatment: Rice seeds were soaked for 24 h in water containing talc-based formulation  (10 g/kg  of seeds) of individual or mixture of bacterial strains. As Soil application: 2.5 kg/ha Pseudomonas fluorescens  mixed with 50 kgs of FYM and then applied to the soil before planting. Pseudomonas fluorescens for control of Rice blast and sheath blight As Seedling root dip: Seedling dip in solution containing formulation of 5g/ litre of water for 30 min. As Foliar application: Spray the product @ 0.2% concentration (1Kg/ha) commencing from 45 days after transplanting at 10 days interval for 3 times depending on the disease intensity. If there is no disease incidence, a single spray is sufficient. Dr . D.K . PANCHESHWAR JAWAHARLAL NEHRU KRISHI VISWA VIDYALAYA, JABALPUR, M.P. College of Agriculture, Balaghat , M.P.

37. THANKS Dr. D. K. PANCHESHWAR ASSISTANT PROFESSOR PLANT PATHOLOGY COLLEGE OF AGRICULTURE JNKVV, MURJHAD FARM BALAGHAT