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UNIVERSITY OF AGRICULTURAL SCIENCES DHARWAD Dr. M Bheemanna Assocate Professor of Entomology Regional Agricultural Research Station Raichur-584102 Karnataka Introduction Rice is grown in over 70 % of the area in Asia and it forms a staple food for about 2.8 billion people. Wide spread utilization of HYV & adoption of intensive practices of crop management, though resulted in substantial increase in yield simultaneously these practices improved the conditions of several pests viz., insects, diseases weeds, rodents and nematodes on the crop. The yield loss in rice is about 24-35 % with a loss to the tune of Rs. 100 crores/year. About 1400 insects covering 100 species are reported is the world to feed on this crop, of which about 20 species are of Economic significance from different parts of the country. In our state about 10-12 pests are important causing significant damage. PESTS OF PADDY Yellow stem borer Brown Plant hopper Green leaf hoppers Caseworm Gall fly White backed plant hopper Paddy skipper Rice leaf folder Earhead bug Horned caterpillar Thrips Other pests Rice stem borer There are 3-4 important stem borers of which the major ones are Scirpophaga incertulas Sesamia inferens chilo suppersatis Scirpophaga incertulas Pyralidae : Lepidoptera Rice stem borer is also commonly known as the paddy stem borer and yellow borer of rice. It is distributed in all Asian countries. It is a regular pest in all parts of India. Seasonal occurrence It occurs both in kharif and rabi/summer seasons. Peak incidence is between April to May The pest affects the crop in the nursery, soon after transplanting and also in the pre-ear head stage. Yellow stem borer (Scirpophaga incertulas (Walk.)) Bright yellowish with brown forewing, long (2 cm) and slender; Snout like labial palps with a clear single black spot on each forewing; Tuft of hairs are present at the tip of abdomen in the female moth; moths are attracted to light in the night Pupa Pupation inside the stem in a silken cacoon; pupal period 6-10 days Newly hatched larva will be pale white in colour with bark brown head and prothoracis shield; Later turn to pale yellow and around 2 cm long; Larval period 30-40 days Eggs are creamy white flattened, laid in mass near the tip of tender leaves and are covered with hairs; Each egg mass contains 15-80 eggs; IP – 5-8 days Ecology Egg development takes place at about 160C with an optimum temperature of 24 to 290C and relative humidity of 90 to 100 percent. Hatching is drastically reduced at low temperatures of 130C and relative humidity of 70 per cent. The rate of larval development is positively correlated to temperature range from 17 to 350C. The threshold for pupal development is 15 to 160C. Nature and symptom of damage Vegetative stage Larvae feed on green tissue of leaf sheath for 2 to 3 days. Bore into the stem at the nodal position and feed on inner tissue of plant – Under Severe conditions, it bores at the base and move upwards – Central leaf whorl does not unfold, turns brown – dries off. Lower leaves remain green. Heading stage • Larvae bore at the peduncle node. • White heads are the resultant effect. • Damage is maximum at this stage. Yield loss Early planted crop 1-19% Late planted crop 38-80% Brown Plant hopper, Nilaparvata lugens (Stal.) Delphacidae:Hemiptera Adults are brown in colour; 4-5 mm long and more or less wedge shaped Macropterans are strong fliers; Hind tibia with a long movable spur Biology: IP – 5 days; NP – 15 days Brachypterans are prolific breeders Eggs are elongated, cigar shaped inserted by female in two rows on wither side of the midrib of the leaf sheath Damaging symptoms • Stage of attack:- Early growth stage but some times serious infestation occurs at post flowering stage • Damaging stages:- Adults (especially brachypterans) and nymphs • Nature of damage:- Congregate at the base of the plant causing hopper burn • Peak occurrence is between NovDec and not cause damage to summer crop. They are also vectors of grassy stunt virus disease. Causes for outbreak • • • • • • • Use of heavy doses of nitrogenous fertilizers Heavy irrigation with constant standing water Use of heavy pesticides specially pyrethroids resulting in resurgence Continuous cropping of paddy (in both the seasons) (monocropping) Close planting will result in prevention of aeration & light. Use of susceptible varieties. In low lying areas severity is more White backed Plant hopper, Sogatella furcifera Delphacidae:Hemiptera The body colour is creamy white; adult measures 3.1-4.0 mm in length; the forewings are uniformly hyaline with darker veins. There is a conspicuous black dot around the middle of the posterior edge of each forewing; the pronotum is pale yellow Brachypterans are prolific breeders Eggs are elongated, cigar shaped inserted by female in two rows on either side of the midrib of the leaf sheath Leaf Folder Cnapholocrocis medinalis (guenee) Lepidoptera : Pyralidae The rice leaf folder, earlier considered as a minor and sporadic pest of rice in many Asian countries, appears to have become increasingly important with the spread of high yielding rice varieties and accompanying changes in cultural practices. It is distributed in many rice growing countries like India, Pakistan, Bangladesh, China, Burma, Bhutan, Indonesia, Japan, Nepal, Malaysia, Kerala, Vietnam, Srilanka, Taiwan, Thailand, Afghanistan and Australia etc. In India it is a serious pest in Karnataka, Madhya Pradesh, Orissa, Andhra Pradesh & Tamilnadu. Paddy Leaf Folder, Cnapahalocrosis medinalis (Guen.) (Pyralidae;Lepidoptera) These are small brownish orange coloured moths and have respectively two and one distinct dark wavy lines on the brownish fore and hind wings which have a dark brown to gray band on their outer margin. Larvae are pale yellowish to green in colour; They fold leaf margin longitudinally and feed the rolled leaves; larval period is 15-27 days; Pupation takes place inside the leaf roll (6-8 days); Total life cycle is 26-42 days. Eggs are laid singly or in pairs on the under surfaces of tender leaf blade; Incubation period is 4 – 7 days Seasonal Occurrence The pest is reported throughout the year although they are most abundant during wet season. Infestation usually higher during late growth stages of the crop. Ecology High humidity and optimum temperatures are conducive factors for the rapid multiplication of the pest. It occurs in abundance where ‘N’ fertilizer dose increase. Damaging Symptoms •Damaging stage:- Larvae •Site of damage:- leaf blade •Nature of damage:- Leaf margins are folded longitudinally and feed the rolled leaves by scraping chlorophyll. The affected leaf dries up. In a severely infested field the whole crop gives a sickly appearance with white patches. The infestation at boot leaf stage results in heavy loss of grain yield Gundhi Bug Leptocorisa oratorius Hemiptera : Alydidae Gundhi bugs are also called stink bugs as a characteristic foul odour is produced by scent glands present on the abdomen These stink bugs are distributed in all the tropical and sub-tropical regions. Seasonal occurrence The population build up is usually noticed at the end of rainy season and declines rapidly during dry months when temperatures are unfavorable. The maximum population is usually observed during September to November months. Paddy ear head bug, Leptocorisa acuta (Thumb) (Alydidae; Hemiptera) Adults are brown coloured with prominent legs and antenna; Female lays eggs on the leaf blade in long rows of 10 -15 eggs. The nymphs are slender and greenish; Both nymphs and adults emit a foul smell after disturbance. Biology: Fecundity; 250-300 eggs with incubation period of 8 days; Nymphal period id 12-15 days and adults live for about 3 – 4 months. •Stage of attack:- Before flowering stage and up to to milky stage •Damaging stages:- Both adults and nymphs •Nature of damage:- Suck the sap of the peduncle, tender stem and milky grains. •Symptoms:- Grains become chaffy; At the spot of the puncture water soaked spots appear and become brown with white center; The quality of the affected grain gets deteriorated. Apart from rice, they also breed on other grasses. Back Ecology All the stages of the pest are vulnerable to changes in temperature and humidity. Favourable conditions: 1. Temperature 27 –28° C Relative Humidity 80-82% 2. Flowering stage warm and cloudy weather and frequent drizzles favour population build up. 3. Extensive weedy areas near rice fields and staggered rice planting favour high population. Unfavorable conditions: Heavy rains reduce population. Confirmation The presence of the insect can be easily determined by an offensive smell. The grains are small, shrivelled, spotty, or deformed. Some grains are also empty. Economic threshold level (ETL) 1 or 2 bugs/Sq.mt or per hill Paddy green leaf hoppers (Cicadellidae; Hemiptera) N. virescens The black spots in the forewing do not extend up to the black distal portion N. nigropictus Male has two black spots extending up to the black distal portion on the forewing N.cincticeps No black spot distal ends of the wings transparent The leafhoppers attack all the aerial parts of rice plant. This pest is distributed in Bangladesh, Burma, Hongkong, Indonesia, Malaysia, Pakistan, Philippines, Taiwan and India. In India it is severe in Andhra Pradesh, Madhya Pradesh, Orissa and moderate to low in other rice growing states. Seasonal Occurrence The hoppers remain active year round In general two population peaks can be observed one in first crop season and the other in second crop season. The insects are usually more abundant during dry season than during wet season. Life History Adult female inserts their eggs in rows under the epidermis of leaf sheath in groups of 5-20, up to 100-135 eggs. Eggs hatch in 5-7 days. Nymphal stage completed in 14-21 days. Ecology The abundance of Green hoppers has been correlated to high temperature, low rainfall and abundant sunshine. The rate of nymphal development is faster at high temperatures. (14.1 days at 35° C and 37.3 days at 20° C). The rapid build up of pest population was observed at tillering and panicle initiation stages of rice crop. The insect can withstand long periods of starvation. They are highly attracted to light at nights. Nature and symptoms of Damage The nymphs and adults cause direct damage to rice crop by sucking sap from leaf sheaths and blades. The feeding marks predispose plants to fungal and bacterial infections. The affected leaves and plants turn to yellow colour and growth is retarded. They indirectly acts as vectors by transmitting virus diseases such as Tungro and Yellow dwarf. They also feed on some grasses like Cynodon dactylon, Echinochloa crussgalli and Eleusine indica, etc., Economic threshold level (ETL) Planting to Pre-Tillering 2 insects/hill in Tungro endemic area. 10 insects/hill in other areas. Mid-Tillering, Panicle Initiation to Tillering20 insects/hill. Rice Case Worm Nymphula depunctalis guen (Lepidoptera : Pyralidae) The rice case worm is an important pest of irrigated and rainfed wet land rice in South and Southeast Asia. Besides rice it infests various other grasses and millets. It is existing in low population in all rice growing areas. Seasonal occurrence In South India, moth population reach two peaks, one during November to December and another during May to June. These peaks coincide with periods of high rainfall and high humidity. Beyond November, they migrate to grassy areas. Life history o The adult moths are white in color & about 6 mm long with a wing expansion of 15 mm. o Eggs are laid in one or two adjacent rows in batches of 10 to 20 on the lower surface of leaves or on the leaf sheath near the water surface. o The egg period vary from 2 to 6 days. o The newly hatched larva is pale green and measures 1.2 mm long. Symptoms 1. Leaf cases floating on water 2. Leaves cut at right angles as with a pair of scissors 3. Leaves with papery upper epidermis that were fed on 4. Skeletonized leaf tissues usually appear ladder-like Asian Gall Midge, Orseolla oryzae Diptera : Cecidomyiidae The gall midge is primarily a pest of low land irrigated rice but has been reported in upland and deep water rice also. The extent and severity of gall midge infestation has significantly increased since 1970’s. The cultivation of high tillering varieties, intensive management and are low parasitization conducive to the rapid multiplication of this pest. It is distributed in almost all rice growing Asian countries. In India it occurs as a serious pest in Madhya Pradesh, Manipur, Orissa, Andhra Pradesh, Bihar, Karnataka and Kerala. About three bio-types were identified in different states. Seasonal Occurrence The gall midge attacks rice crop from the nursery to the end of tillering stage. The pest remains inactive as a pre-pupa in wild rice or weeds during dry season. The incidence is usually high during months of July and August during which period the maximum tillering takes place. Life History • Adult gall midge is similar to female mosquito in appearance. • Eggs are laid in singles or groups on the under side near the base of the rice leaf or on leaf sheath. • Single female is capable of laying 100 – 200 eggs. • Adults are nocturnal in habit and attracted by light. • Male mostly die in 12-18 hours after emergence – while female live for 3 days. • Eggs are shinning white or pinkish, red or yellow in colour – elongated tubular and measures 0.55 mm long. • Newly hatched maggots are grey white and fairly stout with a pointed anterior end. • Larval period is 15-20 days with 3 larval instars. • Pupation takes place inside the galls near the base of the plant. • Pupae have abdominal spines which enable it to wriggle its way to the tip of gall. • Pupal period varies from 2-8 days . • Adult emergence generally takes place at night or early morning. • Entire life cycle takes about 25-38 days. Ecology The pest require high humidity for proper development and hatching of eggs. The favorable condition for fly development is 26 to 300C and 82 to 88 % relative humidity. Heavy rains or storms cause high mortality. Nature and symptoms of damage Damaged tillers turns into tubular galls which dry off without bearing panicles. Main external symptom is SILVER SHOOT or GALL which resembles onion leaf. Fully developed gall is a silvery white hallow tube 1 cm wide and 10 – 30 cm long. Attack to rice seedlings leads to profuse tillering and these new tillers often become infested. Larvae develop only on growing primordia. Yield loss is 0.5% for every unit percent increase in incidence. Three bio types are noticed in India – Which are capable of damaging cultivars, resistant to other populations of the same species. Economic threshold level (ETL) Nursery - One Silver Shoot / Sq.mt. Planting to Pre-Tillering One gall /m2 (endemic areas) or 5 % affected tillers (Nonendemic areas). Mid-Tillering 5 % affected tillers. Paddy skipper Pelopidas mathias F. Hesperidae;Lepidoptera It is common but minor pest. Adult butterfly is dark brown with two white spots on the forewings. Damage They skeletonize the leaf by eating the entire leaf margins and leave the midrib uneaten. Hispa Dicladispa armigera (oliver) Coleoptera : Chrysomelidae This pest was reported to cause considerable crop losses in many Asian countries. It was observed to cause heavy losses even to the extent of 55% in Bangladesh. It is common in wet-land environments and sporadic out of breaks have been reported from many parts the pest usually occurs from July to October. Life History Adults are small shiny black beetles of 5.5 mm long with spines on their wing covers Longevity of female - 20 days and male - 15 days Female beetles lay eggs in singles with in the epidermal layers of the ventral surface of rice leaves. Newly hatched grubs mines to form bloches, pale yellow in color and 2 to 4 mm long. Ecology High humidity after rains and intermittent bright sunshine appears to favor Hispa development in South India. Heavy rainfall in July followed by unusually low rainfall in August and September was characteristic of epidemic years. The late planting in August suffers severe damage with little chance of recovery. Nature and symptoms of damage Both grubs and adult beetles feed on rice plants. Adults scrape chlorophyl first between the veins and the lamina. White parallel streaks on the leaves. Feed on veins also resulting in the formation of blotches on the leaves. In severe infestations the affected leaves turn to brown and the field presents a dried-up appearance. Economic threshold level (ETL) Planting to pre-tillering stage : 1 adult or 1 damaged leaf/hill. Mid-tillering stage : 2 adults or 2 damaged leaves/hill. Paddy thrips Stenchaetothrips biformis (Bagnall) Thripidae; thysanoptera Adults are tiny elongated bark brown insects with narro fringed wings. They are usually seen at the tip of the leaves and sheaths. The female lays eggs singly with in the leaf tissue Damage The infestation is more in the nursery and just transplanted crop.. Both nymphs and adults lacerate the leaf tissue and suck plant sap with the result the leaf margin and in sever cases seedlings are killed. The damage is severe under water stress conditions. Late planted crops are more prone for damage. Damaged leaves roll inwards along the margins, feeding causes leaf drying resulting poor crop growth. Paddy horned caterpillar Melanitis leda ismene C. Satyridae; Lepidoptera The butterfly is dark brown with large wings having a black and yellow and eye spot one on each of forewing It lays white round eggs singly on the leaves Caterpillar is green slightly flattened with two red horn like process on the head and two yellow process in the anal end It pupates in a greenish chrysalis which suspends from the leaf. Damage • The larva feeds on the leaf blade. • Each larva is capable of defoliating a great quantity of leaf tissue during its 3week larval period Whorl Maggot Hydrellia spp Diptera: Ephydridae • Several species of Hydrellia exist in Rice ecosystem . • The pest occurs in India, Bangladesh, Indonesia, Taiwan, Thailand and Phillippines. • The pest is more abundant in Rice crop grown with continuous standing water. • It is found as occasional pest in Rice fields. Life History • The adult flies are dull-grey coloured. • Newly hatched maggots are transparent to light cream in colour and later turn to yellow. • Maggots migrate to un open central leaves and remain there during entire larval period. Nature and symptoms of damage • The maggots attack the leaf blades even before unfurling and the initial damage is characterized by the presence of the blade margins. narrow stripes of whitish arean • Heavy infestation causes a marked stunting of the plant and reduction of tillers. Seasonal occurrence • The pest is abundant during early stages of crop growth. • The infestation ceases at the panicle emergence stage. Paddy swarming caterpillar and climbing cutworm Spodoptera mauritia and S.litura Noctuidae: Lepidoptera It is a miner post in the region The pest is active from July-Sept. Occurs both in nursery and main crop and swarm from field to field. The adults are stout dark brown moth with conspicuous marking on the forewing. Female lays eggs is mass of 200-300 and cover with grayish hairs. • Incubation period lasts for 3-5 days, larvae are green as they grow they become grayish pale green with reddish and yellowish stripes across the body. The larvae are active during night for 20-25 days. They pupate in a earthen cocoon and papal period is for 10-15 days. Symptoms of damage In nursery the larvae cut the plant at base and feed on the fallen plants. In the main field they feed on leaves by climbing the plants leaving behind midrib. If the population is heavy they from field to field causing heavy amount of loss in such cases the field appears as if it is grazed by cattle’s. Paddy grass hopper, (Acrididae;Orthoptera) Hieroglyphus banian : larger in size (3.75cm.) green with three transverse dark lines on the prothorax and poses bluish green hind tibia. It attacks rice sugarcane and other millets. Oxya chinensis : is smaller, about 2.5 cm long, green with longitudinal brown streak on either side of the thorax. This attack rice and grasses • The nymphs and adults feed on leaves leaving the midrib and stalks. • They also nibble the florets and base of panicle causing white ears. Usually they have one brood in a year. • The hopper hatch in June-July from the eggs laid in sandy soil in batches of 30-40 along the bund sides in the previous seasons (Oct-Nov). • The *nymphs feed on grasses of bunds after hatching and move to main crop when crop is planted. Oriental mole cricket Gryllotalpa orientalis Burmeister Orthoptera: Gryllotalpidae Adults and nymphs have enlarged and spade-like front legs Nature and symptoms of damage Adults and nymphs feed on sown seeds and roots. Young plants can die from root loss producing bare spots and missing plant stand in the field ON LEAF • • • • • • • Blast Brown spot Downy mildew Narrow brown leaf spot Leaf smut Stack burn disease : Leaf Scald : : : : : : • Eye spot : • Rust : : Pyricularia oryzae Heliminthosporium oryzae Sclerophthora macrospora Cercospora oryzae Entyloma oryzae Alternaria padwickii Gerlachia oryzae (Rhynchosporium oryzae) Helminthosporium gigantea Uromyces coronatus Puccinia graminis oryzae ON STEM & LEAF SHEATH • Stem rot • Bakane disease : : • Sheath blight • Sheath rot : • Myrothecium blotch : Sclerotium oryzae Fusarium moniliforme Gibberella fujikuroi : Rhizoctonia solani : Thanatophorus cucumeris Sarocladium oryzae : Myrothecium verrucaria GRAIN • False smut / Green smut :Ustilaginoidea virens Claviceps oryzae • Kernal smut :Tilletia barclayana • Udbatta : Balansia oryzae (Ephilis oryzae) • Grain discoloration :Curvularia spp. Blast Well known disease Widely distributed & destructive. Blast is also called as Rice fever disease in China, Japan, and Brusone in Italy. Metcalf (1907) called this as BLAST in English In India first reported from Tanjore -1918. Loss in severe case is to the extent of 70 – 80 %.. Loss due to blast (%) = Y= 0.69 X + 2.8 Where X = % panicle affected Symptoms • On all above ground except sheath. • Reddish brown, spindle shape with ashy gray centre. • 1.5 cm length → 0.5 cm breadth. • Seedling blast • Leaf blast • Nodal blast • Neck blast / Neck rot Leaf blast of Paddy- Pyricularia oryzae Nodal Blast NECK BLAST STEM BORER Reasons: • • • • • • • Susceptibility inversely related to soil moisture Silicification of epidermis is more by low moisture. High air humidity leads to more infection. High N2 induce susceptibility & less silicification Split application of nitrogen reduces susceptibility. Increase in potassium reduces disease. Dew period shortest near water surface and longer near top of rice canopy. Weeds as hosts : Panicum repens, Leersia hexandra & Brachiaria mutica Resistance : ↑ Silica content ↓ N2 application ↑ R Oxidation of polyphenols ↑ Peroxidase ↓ Catalase activity Resistance genotype – TKM – 1,ADT – 25, Tetep, Tadukan, Peta, IR – 8, 36 INTAN & IR 64 ---Earlier Resistance Now Susceptible Yield loss Estimation a) Yield in Epidemic & non epidemic area. b) Resistant & susceptible genotype c) Protected & unprotected by fungicide Sheath blight • Rhizoctonia solani (Thanatephorus cucumeris Perfect state) • This disease is more important in recent years because • Increase in fertilizers usage • High yielding cultivars • Increase in tillers • Increase in humidity Symptoms • Spots on leaf sheath • Oval in shape • Grayish white with brown margin • Cover larger area, above portion of lamina dies on water line surface, 20 % reduction in yield. Sheath blight of Rice – Coticium sasaki Stem rot : Sclerotium oryzae • • • • • • • • • • Very severe in Punjab . It was described in detail by Butler in 1918. Symptoms : Disease at later stage of crop growth. More number of tillers At the base of tiller rottening Black irregular lesion at the water line. Slowly it spreads in vertical manner Mycelial mat & sclerotia inside the sheath. Leading to drying of leaves, with lighter grains. Stem rot - Leptosphaeria salvinii False smut / Green smut Ustilaginoidea virens First report from Tirunelveli in Tamil Nadu in 1878. • More prevalent in seasons favorable for good growth and high yields • The farmers consider its incidence as an omen of God Harvest. Symptoms • • • • • Ears individual ovaries are transformed into large velvety green masses. These are round to oval attain a size of 10mm. Only few spikelets are infected Glumes are not affected but covered by a membrane. Colour changes when it is exposed by breaking of membrane. False smut - Claviceps oryzae (Ustilaginoidea virens) Bacterial diseases Earlier bacteria can affect only foliar parts. But NOW bacterial diseases observed from seedling to maturity So far 11 bacterial diseases of rice on leaf Been reported. Among them bacterial leaf blight and bacterial leaf streak are important. Bacterial leaf blight of paddy Xanthomonas campestris pv. oryzae. • In Fukuoka -1884. Earlier physiology origin / Acidic soil. Proved as bacterium by Ishiyama (1922). In India Srinivasan et. al., in 1959. Due to introduction of high yield strains like Tai Chung Native – 1 Susceptible to this disease it spread to a large area. Post typhoon disease or Rain borne disease Loss Loss is 20 – 30 % in Japan In India 6 – 60 %. The higher loss in India. Stage of crop affected Symptoms • Tiny water soaked lesion at margin of fully opened leaves. • Spots enlarge, turn yellow and roll when leaves are green and later dry. • Wavy Margin on leaf is noticed. • In severe case seedling die leading to “KRESEK” symptoms. • Bacterium spreads through Xylem vessels and reaches glumes, awns. Bacterial leaf streak Xanthomonas oryzicola oryzicola • Another symptom is yellowing of leaves mainly tip leaves • On the surface of young lesions milky/opaque dew drops may be observed in the early morning later dry as yellowish spherical beads • Chaffy grain, broken grain, poor quality grains. Epidemiology • Survival in soil is 1 – 3 months • On seed it survives for three months. • Rice stubbles/roots, pathogen survives for 3 months Entry through natural openings or • Wounds of leaves. → through roots at transplanting or chaffing • Heavy rain, irrigation water & wind increase the disease. • Kresek symptoms in 20 days at 310 C & • 40 days at 210C (i.e. high temp quickly Kresek symptom is seen.) Weeds/wild host Leersia hexandra, L. sayanuka, Leptochloa chinensis, Cyperus rotundus Forecasting : – Growing S & R in field and forecast regularly. – By climatic conditions. : Flood, rain, sunshine, wind & temp. 1. By Bacterial population. 2. Take samples from leaf & analyse. 3. By phage. Resistance : Resistance is related to Number of water pore or hydathodes. • Hardness of leaves. • Short narrow leaves with less horizontal spread • Susceptible have high concentration of free amino acids but less concentration of reducing sugars & poly phenol. • AiKoKu – soto – sango – kei & Nakashin 120 are resistant genes to all three groups of bacteria. • Resistant varieties → IR 20, IR 22, IR-8, TKM – 6, Lead rice from Burma. THANK YOU Narrow brown leaf spot- Cercospora oryzae Sheath rot - Acrcylindrium oryzae Narrow brown leaf spot- Cercospora oryzae Sheath rot - Acrcylindrium oryzae