Rice diseases part_3_zahid

Rice _diseases _part_3_ collected and edited by Syed zahid.
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1. Syed Zahid Hasan , SAU Rice Diseases in Bangladesh PART - 3

2. Leaf scald of rice CO: Microdochium oryzae Damage to plants scalded appearance of leaves Economic importance Leaf scald commonly occurs in Central and South America, where it has caused significant yield losses It also occurs in Asia, Africa, and the U.S The disease is found in upland, rainfed , irrigated, and mangrove areas In India and Bangladesh, yield losses of 23.4% and 20-30% were reported respectively

3. Symptoms Zonate lesions of alternating light tan and dark brown starting from leaf tips or edges Oblong lesions with light brown halos in mature leaves Translucent leaf tips and margins C ontinuous enlargement and coalescing of lesions result in blight of a large part of the leaf blade A ffected areas dry out giving the leaf a scalded appearance I nfected leaf tips also split near the midrib especially when there are strong winds

4. Zonate lesions of alternating light tan and dark brown starting from leaf tips Zonate lesions of alternating light tan and dark brown starting from leaf edges Affected areas dry out giving the leaf a scalded appearance

5. Factors favoring disease development H igh nitrogen W et weather C lose spacing of plants W ounded leaves S ources of infection such as seeds and crop stubbles

6. C ontrol measures Remove weeds Plow under of rice stubbles Remove infected rice ratoons Use resistant varieties Avoid high use of fertilizer. Apply Nitrogen in split Before sowing seed treatment with Knowin 50WP or Genuine 50WP or Turbo 50WP or Freshcozim 50WP @ 3 g/kg seeds Application of Popizole 250EC or Filia 525EC or Potent 250EC or Proven 250EC or Proud 25EC or Propicon 250EC @ 2ml/lit of water at 12-15 days interval for 2-3 times in the field

7. Bacterial leaf blight CO: Xanthomonas oryzae pv . oryzae Damage to plants wilting of seedlings yellowing and drying of leaves reduced yield Economic importance 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 In India, causing yield losses from 6% to 60 %

8. Symptoms Initially water soaked, elongated dull greenish or yellow spot (5-10mm) appear at the tip or margins of the leaf Gradually the spots increase in size forming linear, straw colored or yellow-orange stripes on leaf blades or leaf tips or blighted area on one or both margins of leaves. The inner margin of the lesion is wavy, irregular or ragged The stripes may coalesce to cover the entire leaf blade Drops of bacterial ooze or exudates may be observed in the morning on young lesions Severely infected field look like as it was burnt by fire.

9. Dried up bacterial ooze Bacterial ooze Severely infected field look like as burnt by fire linear, straw colored or yellow-orange stripes on leaf blades

10. Factors favoring disease development presence of weeds presence of rice stubbles and ratoons of infected plants presence of bacteria in the rice paddy and irrigation canals warm temperature (25−34°C), high humidity (above 70 %), rain and deep water over fertilization ( excess silica and magnesium) Potassium and phosphorus deficiency handling of seedlings at transplanting

11. Disease cycle

12. C ontrol measures Practicing field sanitation such as removing weed hosts, rice straws, ratoons , and volunteer seedlings Collect seeds from only healthy crop Practice balance fertilization providing good drainage during severe flooding proper plant spacing are recommended Dry the diseased field and allow to crack before irrigating Use resistant variety, such as IR-20, IR-22, BR-14,BR-11, etc Seeds treated with Agrimycin @ 0.025 % solution for 12 hrs before sowing Application of bleaching powder @15kg/ha in the field Application of Bactroban 20WP @ 500g/ha in the field

13. Bacterial leaf streak CO: Xanthomonas oryzae pv . oryzicola Damage to plants browning and drying of leaves reduced grain weight due to loss of photosynthetic area Economic importance Bacterial leaf streak is widely distributed in Taiwan, southern China, Southeast Asian countries, India, and West Africa Losses as high as 32.3% grain weight due to BLS were reported Based on reported, yield loss caused by BLS can range from 8− 17% in the wet season, and 1−3 % in the dry season

14. Symptoms Symptoms initially appear as small, water-soaked, linear lesions between leaf veins These streaks are initially dark green and later become light brown to yellowish gray The lesions are translucent when held against the light Entire leaves may become brown and die when the disease is very severe Under humid conditions, yellow droplets of bacterial ooze, which contain masses of bacterial cells, observed on the surface of leaves

15. light brown to yellowish gray linear streak on leaf

16. Factors favoring disease development presence of the bacteria on leaves and in the water or those surviving in the debris left after harvest high temperature( above 34 C ) and high humidity early stage of planting from maximum tillering to panicle initiation

17. Disease cycle

18. C ontrol measures Same as BLB

19. Tungro of rice Tungro virus disease is transmitted by leafhoppers, where in the most efficient vector is the green leafhopper, Nephotettix virescens The disease complex is associated with rice tungro baciliform virus (RTBV) and rice tungro spherical virus (RTSV) RTBV cannot be transmitted by leafhoppers unless RTSV is present Insects could acquire the virus from any part of the infected plant. After acquiring the virus, the vector can immediately transmit to the plants Damage to plants leaf discoloration sterile or partially filled grains

20. Economic importance Tungro is one of the most damaging and destructive diseases of rice in countries in Southeast Asia Plant infected with the virus at the early crop growth stage could have as high as 100% yield loss in severe cases The damage caused by the disease depends on-------- the variety used, the plant stage when infection occurs the virus particles, and the environmental conditions

21. Symptoms Plants affected by tungro exhibit stunting and reduced tillering The leaves become yellow or orange-yellow, may also have rust-colored spots Discoloration begins from leaf tip and extends down to the blade or the lower leaf portion Delayed flowering, panicles small and not completely exerted Most panicles sterile or partially filled grains

22. yellow or orange-yellow leaves with rust-colored spots Plants affected by tungro exhibit stunting Green leafhopper T ungro affected rice field

23. Factors favoring disease development Presence of the virus sources Presence of the vector Age and susceptibility of host plants Synchronization of the three above factors All growth stages of the rice plant specifically the vegetative stage

24. Transmission cycle of tungro disease (non-persistent type) of rice

25. C ontrol measures Elimination of weeds and diseased plants Adjusting the date of planting is recommended Planting of resistant varieties against tungro virus disease eg . Segadis , Pata , Mala, Brisail , BR-5, BR-8, Nizersail , etc Destroy GLH through light trapping Control the incidence of GLH by Malaton 57 EC or Fyfanon 57EC or Hilthion 57EC or Sumady 57EC or Malason 57EC or MB Malathion 57 EC or Anthion 57EC or Guruthion 57Ec or Maladion 57EC @ 2ml/lit of water at 12-15 days interval for 2-3 times in the field

26. Grassy stunt of rice CA: Rice grassy stunt virus (RGSV) T ransmitted by the brown planthopper ( Nilaparvata lugens ) Damage to plants reduces yields by inhibiting panicle production Economic importance The grassy stunt virus is not a widespread problem It became a serious problem during brown planthopper outbreaks During sporadic outbreaks, it can cause serious damage in limited areas Yield loss is higher when infection occurs early in the season

27. Symptoms Diseased hills are severely stunted with excessive tillering and a very upright growth habit Diseased hills has a grassy and rosette appearance Leaves short, narrow, and yellowish green with numerous small rusty spots or patches, which form blotches Retention of green coloration of the leaves after application of sufficient nitrogenous fertilizers Infected plants usually survive until maturity, but produce no panicles The symptom develops 10-20 days after infection

28. Diseased hills are severely stunted with excessive tillering , very upright growth habit and grassy & rosette appearance Brown planthopper short , narrow, and yellowish green Leaves

29. Factors favoring disease development Infected stubble and volunteer rice availability of the vector all growth stages especially tillering stage of the rice crop

30. Transmission cycle of grassy stunt diseases (persistent type) of rice

31. C ontrol measures Elimination of weeds and diseased plants Adjusting the date of planting is recommended Planting of resistant varieties against BPH like IR26, IR64, IR36, IR56, IR72 Control the incidence of BPH by Hilthion 57EC or Malasun 57EC or Razthion 57EC or Ashation 57EC or Mapathion 57EC or Quiathion 57EC or Sumady 57EC or Malason 57EC or MB Malathion 57 EC or Anthion 57EC or Guruthion 57Ec or Maladion 57EC @ 2ml/lit of water at 12-15 days interval for 2-3 times in the field

32. Ufra of rice CO: Ditylenchus angustus Ufra Disease a disease of deepwater rice caused by feeding damage of the nematode Ditylenchus angustus Normally , the disease is observed in deepwater rice growing areas such as Barisal, Dhaka, Sirajganj , Faridpur , Jessore , Khulna, Noakhali , Patuakhali and Sylhet districts The ufra nematode feeds ectoparasitically on the inner surface of unmerged leaves, sheaths, buds, and developing panicles In Bangladesh, irrigated or deepwater rice usually starts showing ufra symptoms from late July or August. Crop loss estimates were 17-57% The symptoms of ufra disease are noticed at three growth stages of rice plant   Seedling ufra / ufra -I Thor ufra / swollen ufra / ufra-II Pucca ufra / ripe ufra / ufra -III

33. Symptoms (Seedling ufra ) Splash of white patches appear on the growing leaves and leaf bases of rice The white patches turn into brown discoloration Severely infected leaves becomes wither and die Splash of white patches on the growing leaves and leaf bases of rice

34. Symptoms (Thor ufra ) The ear remains within the sheath, swells up but fails to emerge Ultimately the sheath enclosing the swollen ear becomes spindle shaped The panicle by this time becomes twisted and fails to produce grains or produce sterile grains. Twisted and distorted leaves & panicles and fails to produce grains

35. Symptoms ( Pucca ufra ) The ear emerges from the leaf sheath (Flag leaf ) The peduncle and spikelets become dark brown to black The lower part of the ear gives a burnt out appearance and produces few grains of poor quality near the tip lower part of the ear gives a burnt out appearance and produces few grains of poor quality near the tip

36. Factors favoring disease development High humidity during growing stages Temperature 28-30 C (Development and infection is favored)

37. C ontrol measures Burn the stubbles and debris in the field Rotation of crops Heat the soil upto a death of 3-4 inch and uniformly Completely drying fields when they are fallow Plough the land deep and expose it for drying Cultivate resistant varieties such as Raida , Bajail-65, Digha . Apply of Furadan 5G or Edfuran 5G or Brifur 5G or Cemifuran 5G or Promofuran 5G or Calfuran 5G or Dinafuran 5G @ 20kg/ha

38. Root knot of rice CO: Meloidogyne graminicola Root knot disease of rice is widely distributed in rice growing areas of the world, viz., India, U.S.A., South America, Burma, Vietnam, Taiwan, Indonesia, Philippines, Laos, Thailand Bangladesh and Pakistan M . graminicola is a damaging parasite on upland, lowland and deepwater rice The rice root-knot nematode is considered one of the limiting factors in rice production in all rice ecosystems. 20% losses have been reported under intermittent flooding, 30% in semi deep water and 70% under saturated condition 16 to 20% yield loss caused by M. graminicola in low land rainfed rice in Bangladesh

39. Symptoms The above ground symptoms of root knot disease of rice are yellowing, dwarfing, drying of leaves and wilting Infected plants fail to respond to irrigation and fertilizer below ground symptoms include formation of hook, spindle or club shaped galls on the roots system of rice plants

40. Galls on the roots

41. Factors favoring disease development Roots of infected plants S oil moisture of 20% to 30% Soil dryness at rice tillering and panicle initiation Susceptible rice plants P resence of relatively broad host range

42. What it does Infective second stage juvenile of M. graminicola penetrates through the root tips and takes about a minimum of 41 hours Females develop within the root and eggs are laid in the cortex Galls are formed in 72 hours The juveniles or immatures remain in the maternal gall or migrate intercellularly through the aerenchymatous tissues of the cortex to new feeding sites within the same root.

43. Continuous flooding Raising the rice seedlings in flooded soils Crop rotation Use resistant varieties Use nematicidal compounds: volatile (fumigants) and nonvolatile nematicides applied as soil drenches Treat seeds with EPN and carbofuran Apply of Furadan 5G or Edfuran 5G or Brifur 5G or Cemifuran 5G or Promofuran 5G or Calfuran 5G or Dinafuran 5G @ 20kg/ha C ontrol measures

44. THANKS TO ALL