Diseases of rice.ppt kill bill ingionggffdd

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1. Diseases of rice
Blast -Pyriculariaoryzae(Syn: P. grisea)
(Sexual stage: Magnaporthegrisea)
Leafblast:Ontheleaves,thelesionsappear
assmallbluishgreenflecks,whichenlarge
undermoistweathertoformthe
characteristicspindleshapedspotswithgrey
centreanddarkbrownmargin.
Nodalblast:Spotsalsoappearonsheath.
Blacklesionsappearonnodesgirdlingthem.
Theaffectednodesmaybreakupandallthe
plantpartsabovetheinfectednodesmaydie.
Neckblast:Thefungusattacksthepeduncle
andthelesionturnstobrownish-blackwhich
isreferredtoasrottenneck/neckrot/
panicleblast

2. Pathogen
Mycelium-hyalinetoolivaceousandseptate.
Conidiaproducedinclustersonlongseptate,olivaceousconidiophores.
Conidiaarepyriformtoellipsoid,attachedatthebroaderbasebyahilum.
Conidiaarehyalinetopaleolivegreen,usually3celled.
Ascosporesarehyaline,fusiform,4celledandslightlycurved.

3. •Primarilythroughairborneconidia
•Myceliumandconidiaintheinfectedstrawandseedsaremajor
sourcesofinoculum.
•Irrigationwatermaycarrytheconidiatodifferentfields.
•Thefungusalsosurvivesoncollateralhostsviz.,Panicumrepens,
Digitariamarginata,Brachiariamutica,Leersiahexandraand
Echinochloacrusgalli.
FavourableConditions
•Intermittentdrizzles,cloudyweather,moreofrainydays,
longerdurationofdewandhighrelativehumidity(93-99per
cent).
•Lownighttemperature(between15-20°Corlessthan
26°C).
•Availabilityofcollateralhostsandexcessdoseofnitrogen.
InJapan,thefirstleafblastforecastingmodelwasdevelopednamedas
BLAST.Laterseveralothermodelshavealsobeendevelopednamely,
PYRICULARIA,PYRIVIEW,BLASTAM,EPIBLAandPBLAST.

4. Management
Culturalmethods
Removecollateralweedhostsfrombundsandchannels
Useonlydiseasefreeseedlings
Avoidexcessnitrogen
ApplyNinthreesplitdoses(50%asbasal,25%attilleringphaseand
25%atpanicleinitiationstage)
UseresistantvarietieslikeCO47,CO52andTNAUricehybridCO4
andmoderatelyresistantvarietieslikeCO50andCO51inendemic
areas
Chemicalmethod
Spraytricyclozole75WP@500g/haormetominostrobin20SC@500ml/ha
orAzoxystrobin25SC@500ml/haafterobservinginitialinfectionofthe
disease
Biologicalcontrol
TreattheseedswithBacillussubtilisTNAUformulation@10g/kgofseeds
[email protected]
seedlings
[email protected]/ha
FoliarspraywithBacillussubtilisTNAU@5g/l

5. Brown Spot -Helminthosporium oryzae
(Syn: Drechslera oryzae)
(Sexual stage: Cochliobolus miyabeanus)
Symptoms
Thefungusattacksthecropfromseedlingto
milkystageinmainfield.
Symptomsappearasminutespotsonthe
coleoptile,leafblade,leafsheath,andglume,
beingmostprominentontheleafbladeand
glumes.
Thespotsbecomecylindricaloroval,darkbrown
withyellowhalolaterbecomingcircular.
Severalspotscoalesceandtheleafdriesup.
Darkbrownorblackspotsalsoappearon
glumesleadingtograindiscoloration.
Itcausesfailureofseedgermination,seedling
mortalityandreducesthegrainqualityand
weight.

6. Pathogen
Brown septatemycelium.
Conidiophores arise singly or in small groups.
They are geniculate, brown in colour.
Conidia are usually curved with a bulged center and
tapered ends. They are pale to golden brown in colourand
are 6-14 septate.
It produces peritheciawith ascicontaining 6-15 septate,
filamentous or long cylinderical, hyaline to pale olive green
ascospores.
It produces terpenoidphytotoxinscalled ophiobolinA ,
ophiobolinB and ophiobolinI.
Favourable Conditions
• Temperature of 25-30°C with relative humidity above 80%.
• Excess of nitrogen aggravates the disease severity.
Primary source -Infected seeds and stubbles
Secondary spread-Air borne conidia
The fungus also survives on collateral hosts like Leersia hexandra
and Echinochloa colonum.

7. Management
Fieldsanitation-removalofcollateralhostsandinfecteddebris
fromthefield.
Useofslowreleasenitrogenousfertilizersisadvisable.
Usediseasefreeseeds
Spraymetominostrobin@500ml/haafterobservinginitial
infectionofthedisease
Forcombinedinfectionofblastandbrownspot
Spraypropineb54.2%+tricyclazole15%WP@1250gm/ha
afterobservinginitialinfectionofthedisease.
Forcombinedinfectionofblast,sheathblightandbrown
spot
Sprayazoxystrobin16.7%+tricyclazole33.3%SC@500ml/ha
afterobservinginitialinfectionofthedisease

8. Sheath blight -Rhizoctonia solani
(Sexual stage: Thanetophorus cucumeris)
Symptoms
Thefungusaffectsthecropfromtilleringto
headingstage.
Initialsymptomsarenoticedonleafsheaths
nearwaterlevel.
Ontheleafsheathovalorellipticalorirregular
greenishgreyspotsareformed.
Asthespotsenlarge,thecentrebecomes
greyishwhitewithanirregularblackishbrownor
purplebrownborder.
Lesionsontheupperpartsofplantsextend
rapidlycoalesingwitheachothertocoverentire
tillersfromthewaterlinetotheflagleaf.
Thepresenceofseverallargelesionsonaleaf
sheathusuallycausesdeathofthewholeleaf,
andinseverecasesalltheleavesofaplant
maybeblighted

9. Pathogen
Mycelium is septate, which are hyalinewhen
young, yellowish brown when old.
It produces large number of spherical brown
sclerotia.
Favourable Conditions
• High relative humidity (96-97 per cent), high temperature (30-
32°C).
• Closer planting.
• Heavy doses of nitrogenous fertilizers.
Spread
The pathogen can survive as sclerotia or mycelium in dry soil for
about 20 months but for 5-8 months in moist soil.
Sclerotia spread through irrigation water. The fungus has a wide
host
range.

11. Management
Cultural method
Deep ploughing in summer and burning of stubbles.
Apply neem cake @ 150 kg/ha to soil
Botanical
Foliar spray with neem oil 3% @ 15 l/ha starting from
disease appearance
Chemicial method
Spray azoxystrobin @ 500 ml/ha or hexaconazole 75% WG
@ 100 mg/l.

12. Sheath rot -Sarocladiumoryzae(Syn:
Acrocylindriumoryzae)
Symptoms
•Initialsymptomsarenoticedonlyontheupper
mostleafsheathenclosingyoungpanicles.
•Theflagleafsheathshowoblongorirregular
greyishbrownspots.
•Theyenlargeanddevelopgreycentreandbrown
marginscoveringmajorportionsoftheleafsheath.
•Theyoungpaniclesremainwithinthesheathor
emergepartially.Thepaniclesrotandabundant
whitishpowderyfungalgrowthisseeninsidethe
leafsheath.
Pathogen
The fungus produces whitish, sparsely branched,
septate mycelium.
Conidia are hyaline, smooth, single celled and
cylindrical in shape.

13. FavourableConditions
• Closer planting
• High doses of nitrogen
• High humidity and temperature around 25-30°C
• Injuries made by leaf folder, brown plant hopper and mites increase
infection
Spread
•The disease spreads mainly through air-borne conidia and also seed-
borne.
•Primary source of inoculumis by means of infected plant debris.
Secondary spread is by means of air borne conidia produced on the
leaf sheath.

14. Management
Botanicals
Sprayneemoil3%orIpomoealeafpowderextract@25kg/haorProsopis
leafpowderextract@25kg/ha.Firstsprayatbootleafstageandsecond
at15dayslater
Chemicalmethod
Spraymetominostrobin@500ml/haorhexaconazole75%WG@100mg/
lit
Biologicalcontrol
TreattheseedswithBacillussubtilisTNAUformulation@10g/kgofseeds
[email protected]
seedlings
[email protected]/ha
FoliarspraywithBacillussubtilisTNAU@5g/l

15. Stem rot –Sclerotium oryzae (Sexual stage: Magnaporthe salvinii)
Smallblacklesionsareformedonthe
outerleafsheath
andtheyenlargeandreachtheinnerleaf
sheathalso.
Theaffectedtissuesrotandabundant
smallblacksclerotiaareseeninthe
rottingtissues.Theculmcollapsesand
plantslodge.
Thesclerotiaarecarriedinstubblesafter
harvest.
Pathogen
Whitetogreyishhyphae,sphericalblack
andshinysclerotia,visibletonakedeyesas
blackmasses.
FavourableConditions
•Infestationofleafhoppersandstemborer.
•Highdosesofnitrogenousfertilizers.

16. Thesclerotiasurviveinstubblesandstrawthosearecarriedthrough
irrigationwater.
Thefungusoverwintersandsurvivesforlongperiodsassclerotiain
theupperlayers(2-3inches)ofthesoilprofile.
Viablesclerotiahavebeenfoundinfieldsforupto6yearsaftera
ricecrop.
Thesclerotiaarebuoyantandfloattothesurfaceoffloodwater
wheretheycontact,germinate,andinfectricetillersnearthewater
line.
Management
•Deepploughinginsummerandburningstubblestoeliminate
sclerotia.
•Useofbalancedapplicationoffertilizer.
•Avoidflowofirrigationwaterfrominfectedtohealthyfields.
•Drainingirrigationwaterandlettingsoiltodry.

17. Udbattadisease -Ephelisoryzae
(Sexual stage: Balansiaoryzae-sativa)
Symptoms
Symptomsappearatthetimeofpanicleemergence.
Theentireearheadisconvertedintoastraightcompactcylindricalblack
spikelikestructuresincetheinfectedpanicleismattedtogetherbythe
fungalmycelium.
Thespikeletsarecementedtothecentralrachisandthesizeis
remarkablyreduced.Theentirespikeiscoveredbygreyishstromawith
convexpycnidiaimmersedinside.
Pathogen
Pycnidiospores are hyaline, needle shaped and 4-5
celled.
Management
• The pathogen is internally seed borne.
• Hot water seed treatment at 45°C for 10 min. effectively
controls the disease.
• Removal of collateral hosts Isachne elegans
, Eragrostis tenuifolia and Cynadon dactylon.

18. Stack burn disease -Trichoconis padwickii (Syn: Alternaria padwickii)
Symptoms
Leavesandripeninggrainsareaffected.
Onleavescirculartoovalspotswithdarkbrown
marginsareformed.
Thecenterofthespotturnslightbrownorwhite
withnumerousminutedots.
Ontheglumesreddishbrownspotsappear.The
kernelsmayshrivelandbecomebrittle.
Pathogen
Conidia are elongated with a long beak at the tip, 3 to
5 septate, thick walled and constricted at the septa.
Management
• Treat the seeds with Thiram or Captan at 2g/kg.
• Hot water treatment at 54°C for 15 minutes is also
effective.
• Burn the stubbles and straw in the field.

19. Bunt or Kernel Smut or black smut -Tilletia barclayana
Minute black pustules or streaks
are formed on the grains which
burst open at the time of ripening.
The grains may be partially or
entirely replaced by the fungal
spores.
The sorus pushes the glumes
apart exposing the black mass of
spores.
Only a few flowers are infected in
an inflorescence.
The fungus survives as
chlamydospores for one or more
years under normal condition and
3 years in stored grains.

20. Grain discolouration -Drechslera oryzae, D. rostratum, D.tetramera, Curvularia
lunata, Trichoconis padwickii, Sarocladium oryzae, Alternaria tenuis, Fusarium
moniliforme, Cladosporium herbarum, Epicoccum purpurascens,
Cephalosporium sp., Phoma sp.
Thegrainsmaybeinfectedbyvarious
organismsbeforeorafterharvestingcausing
discoloration,theextentofwhichvaries
accordingtoseasonandlocality.
Theinfectionmaybeexternalorinternal
causingdiscolorationoftheglumesorkernels
orboth.
Darkbrownorblackspotsappearonthe
grains.
Thediscolorationmaybered,yellow,orange,
pinkorblack,dependingupontheorganism
involvedandthedegreeofinfection.
Thisdiseaseisresponsibleforquantitativeand
qualitativelossesofgrains.

21. FavourableConditions
•Highhumidityandcloudyweatherduringheadingstage
Thediseasespreadsmainlythroughair-borneconidiaandthefungus
survivesasparasiteandsaprophyteintheinfectedgrains,plantdebris
andalsoonothercropdebris.
Management
Spray carbendazim+ thiram+ mancozeb(1:1:1) @ 0.2% at 50% flowering
stage
Spray tebuconazole50% + trifloxystrobin25% WG @ 200 gm/ha at 50%
flowering stage
For combined infection of sheath blight, leaf blast and neck blast
and grain discolouration-Spray tebuconazole50% + trifloxystrobin25%
@ 200 gm/ha
Store the grains with 13.5-14% moisture content.

22. Foot rot or Bakanae disease -Fusarium moniliforme
(Sexual stage: Gibberella fujikuroi)
Symptoms
Infectedseedlingsinnurseryareleanandlanky,
muchtalleranddieaftersometime.
Inthemainfield,theaffectedplantshavetalllanky
tillerswithlongerinternodesandaerialadventitious
rootsfromthenodesabovegroundlevel.
Therootsystemisfibrousandbushy.
Theplantsarekilledbeforeearheadformationorthey
produceonlysterilespikelets.
Pathogen
Fungus produces both macroconidiaand microconidia.
Microconidia are hyaline, single celled and oval.
Macroconidiaare slightly sickle shaped, and two to five
celled.
The fungus produces the phytotoxin, fusaricacid, which
is non-host specific.

23. False smut -Ustilaginoidea virens
(Syn: Claviceps oryzae -sativa)
Thefungustransformsindividual
ovaries/grainsintogreenishspore
ballsofvelvettyappearance.
Fewspikeletsinapanicleare
affected.
Pathogen
Smut spores are formed as spore balls
which are spherical to elliptical, warty
and olivaceous.

24. Spread
Grassesandwildricespeciesarealternatehosts
Ascosporesproducedfromsclerotiaactasprimarysourceofinfectionwhile
chalmydosporesaresecondarysourceofinfection.
Chlamydosporesareair-borne,abundantatheadingstage.
Favorableconditions
•Rainfallandcloudyweatherduringfloweringandmaturity
Management
Twosprayswithpropiconazole25EC@500ml/haorcopperhydroxide77WP
@1.25kg/haatbootleafand50%floweringstages

25. Bacterial leaf blight -Xanthomonas oryzae pv. oryzae
Thediseaseisusuallynoticedatthe
timeofheadingbutitcanoccur
earlieralso.
Seedlingsinthenurseryshow
circular,yellowspotsinthemargin,
thatenlarge,coalesceleadingto
dryingoffoliage.
“Kresek”symptomisseenin
seedlings,1-2weeks after
transplanting.
Thebacteriaenterthroughthecut
woundsintheleaftips,become
systemicandcausedeathofentire
seedling.

26. Ingrownupplantswatersoaked,translucentlesionsappearnearthe
leafmargin.
Thelesionsenlargebothinlengthandwidthwithawavymarginand
turnstrawyellowwithinafewdays,coveringtheentireleaf.
Thelesionscovertheentirelaminawhichturnswhiteorstrawcoloured.
Milkyoropaquedewdropscontainingbacterialmassesareformedon
younglesionsintheearlymorning.Theydryuponthesurfaceleavinga
whiteencrustation.
Theaffectedgrainshavediscolouredspots.Ifthecutendofleafis
dippedinwater,itbecomesturbidbecauseofbacterialooze.
Pathogen
Thebacteriumisaerobic,gramnegative,nonsporeforming,rodwithsize
rangingfrom1-2x0.8-1.0mwithmonotrichouspolarflagellum.
Bacterialcoloniesarecircular,convexwithentiremargins,whitishyellowto
strawyellowcolored.

27. FavorableConditions
•Clippingoftipoftheseedlingatthetimeoftransplanting
•Heavyrain,heavydew,flooding,deepirrigationwater
•Severewindandtemperatureof25-30C
•Applicationofexcessivenitrogen,especiallylatetop
dressing
Thepathogensurvivesinsoilandintheinfectedstubblesand
oncollateralhostsLeersiaspp.,Plantagonajor,Paspalum
dictum,and
Cyanodondactylon.
Thepathogenspreadsthroughirrigationwaterandalso
throughrainstorms.

28. Management
•Burnthestubbles.
•Useoptimumdoseoffertilizers.
•Avoidclippingoftipofseedlingatthetimeoftransplanting.
•Avoidfloodedconditions.Removeweedhosts.
•Spray20%freshcowdungextracttwice(startingfrominitial
appearanceofthediseaseandanotheratfortnightlyinterval)
•[email protected]/ha30and45days
after
plantingorspraystreptomycinsulphate+tetracyclinecombination
@[email protected]/ha.Ifnecessaryrepeat15
dayslater
•Applicationofbleachingpowder@5kg/haintheirrigationwateris
recommendedatthekresekstage
•Sprayneemoil60EC@3%orNSKE@5%forthecontrolofsheath
rot,sheathblight,graindiscolourationandbacterialblight

29. Bacterial leaf streak -Xanthomonas oryzae pv. Oryzicola
Symptoms
Fine translucent streaks are formed on the veins and the lesions enlarge
lengthwise and infect larger veins and turn brown.
On the surface of the lesions, bacterial ooze out and form small yellow band-like
exudates under humid conditions.
In severe cases the leaves dry up.

30. Rice Tungro Disease (RTD) -Rice tungro bacilliform virus
(RTBV) and Rice tungro spherical virus (RTSV)
Symptoms
Infectionoccursbothinthenurseryand
mainfield.Plantsaremarkedlystunted.
Leavesshowyellowtoorange
discolorationandinterveinalchlorosis
Youngleavesaresometimesmottled
whilerustyspotsappearonolder
leaves.
Tilleringisreducedwithpoorroot
system.
Paniclesnotformedinveryearly
infection,ifformed,remainsmallwith
few,deformedandchaffygrains.

31. Pathogen
Twomorphologicallyunrelatedvirusespresentinphloemcells.
Ricetungrobacilliformvirus(RTBV)bacilliformcapsid,circulardsDNA
genome
Ricetungrosphericalvirus(RTSV)isometriccapsidssRNAgenome.
Transmission-leafhoppervectorNephotettixvirescens
Boththeparticlesaretransmittedsemipersistently,inthevectorthe
particlesarenoncirculativeandnonpropagative.
PlantsinfectedwithRTSValonemaybesymptomlessorexhibitonly
mildstunting.
RTBV enhances thesymptoms caused by RTSV.
RTSVcanbeacquiredfromtheinfectedplantindependentlyofRTBV,
butacquisitionofRTBVisdependentonRTSVwhichactsasahelper
virus.

32. Physicalmethods
Setuplighttrapstoattractandcontroltheleafhoppervectorsaswellas
tomonitorthepopulation.
Intheearlymorning,thepopulationofleafhopperalightingnearthelight
trapshouldbekilledbyspraying/dustingtheinsecticides.Thisshouldbe
practicedeveryday
Chemicalmethod
Spray phosphamidon 40% SL 1000 ml/ha
carbofuran 3% CG 25 kg/ha
buprofezin 25% SC 800 g/ha
carbosulfan 25% EC 8001000 ml/ha
fipronil 5% SC 1000-1500 g/ha or fipronil 0.3% G 16.67-25 kg/ha
imidacloprid 17.8% SL 100 -125 ml/ha
thiamethoxam 25% WG 100 g/ha
The vegetation on the bunds should also be sprayed with the insecticides

33. Rice Grassy stunt disease -Rice grassy stunt tenuivirus
Symptoms
Plantsaremarkedlystuntedwithexcessivetillering
and an erect growth habit.
Leavesbecomenarrow,palegreenwithsmallrusty
spots.
Mayproduceafewsmallpanicleswhichbeardark
brownunfilledgrains.
Pathogen
Rice grassy stunt tenuivirus, flexuous, filamentous 950-1350nm long x 6nm
wide, ssRNA genome
Disease spreads by the brown plant hopper, Nilaparvata lugens, in a persistent
manner.
Ratoon crop and presence of vector perpetuate the disease from one crop to
other.

34. Rice dwarf –Rice dwarf virus
Symptoms
Infected plants show stunted growth, reduced tilleringand root system.
Leaves show chloroticspecks turning to streaks along the veins.
In early stage of infection no ear heads formed.
Pathogen
• The virus is spherical, 70nm diameter with an envelope, dsRNA genome.
Spread
Spreads by leafhopper feeding by Nephotettix cincticeps, Recllia dorsalis
and N. nigropictus in a persistent manner. The transmission is transovarial
through eggs.
Gramineous weeds Echinochloa crusgalli and Panicum miliaceaum serve as
source of inoculum.
Management
• Destory weed host that serve as source of inoculum
• Spray Phosphamidon or Fenthinon 500 ml or Monocrotophos 1 lit/ha.

35. Rice ragged stunt disease –Rice ragged stunt virus
Symptoms
• Formation of ragged leaves with irregular
margins, vein swelling, enations
on leaf veins may be formed
• Stunting of plants, delayed flowering, production
of nodal branches and incomplete emergence of
panicles
Pathogen
• Spherical virus (Figivirus), 65 nm diameter, dsRNA
genome
Spreads through brown planthopper, Nilaparvata
lugens transmitted in a persistent manner.

36. Rice yellow dwarf disease –Rice yellow dwarf virus
Symptoms
Prominentstuntingofplantsandexcessive
tilleringarethecharacteristicsymptomsofthe
disease.
Leavesyellowishgreentowhitishgreen,
becomesoftanddroop.
Plantsusuallyremainsterilebutsometimes
mayproducesmallpanicleswithunfilledgrains
Pathogen
• Caused by a phytoplasma (rice yellow dwarf
phytoplasma designated as a
novel taxon, ‘Candidatus Phytoplasma oryzae’)
The disease is transmitted by leafhopper vectors
Nephotettix sp.
The pathogen survives on several grass weeds.

37. Cultural method
Plough the stubbles as soon as the crop is harvested to prevent the
survival of orange leaf pathogen during offseason
Chemical method
Spray phosphamidon 40% SL 1000 ml/ha or
carbofuran 3% CG 25 kg/ha or
buprofezin 25% SC 800 g/ha or
carbosulfan 25% EC 8001000 ml/ha or
fipronil 5% SC 1000-1500 g/ha or fipronil 0.3% G 6.67-25 kg/ha or
imidacloprid 17.8% SL 100 -125 ml/ha or
thiamethoxam 25% WG 100 g/ha
The vegetation on the bunds should also be sprayed with the
insecticides