Rice _diseases _part_3_ collected and edited by Syed zahid. Read book for details.

1. Syed Zahid Hasan, SAU
Rice Diseases in Bangladesh
 PART - 3

2. Leaf scald of rice
CO: Microdochium oryzae
Damage to plants
 scaldedappearanceof leaves
Economic importance
 Leaf scaldcommonly occursin Centraland SouthAmerica,whereit
has causedsignificantyield losses
 It alsooccurs inAsia,Africa,and theU.S
 The diseaseis found in upland,rainfed,irrigated,and mangrove areas
 In India and Bangladesh,yield losses of 23.4%and20-30%
werereportedrespectively

3. Symptoms
 Zonate lesions of alternatinglighttanand dark brownstarting
fromleaftipsoredges
 Oblonglesionswithlight brownhalos in matureleaves
 Translucentleaf tipsand margins
 Continuousenlargementand coalescingof lesionsresultin
blight of a largepart of the leafblade
 Affectedareas dry out giving theleaf a scaldedappearance
 Infectedleaf tipsalso splitnearthe midribespeciallywhen
thereare strongwinds

4. Zonatelesionsofalternating
lighttananddarkbrown
startingfromleaftips
Zonatelesionsof
alternating lighttanand
darkbrownstarting
fromleafedges
Affected areasdryout
giving theleafa
scaldedappearance

5. Factors favoring disease development
 High nitrogen
 Wet weather
 Close spacing of plants
 Wounded leaves
 Sources of infection such as seeds
and crop stubbles

6. Control measures
 Removeweeds
 Plow under of ricestubbles
 Remove infectedriceratoons
 Use resistantvarieties
 Avoid high use of fertilizer.Apply Nitrogenin split
 Beforesowingseed treatmentwithKnowin50WPor Genuine50WPor
Turbo 50WPor Freshcozim50WP@ 3 g/kgseeds
 ApplicationofPopizole 250EC or Filia 525EC or Potent 250EC or
Proven 250EC orProud 25EC orPropicon 250EC @ 2ml/litofwater
at 12-15days intervalfor2-3times inthe field

7. Bacterial leaf blight
CO: Xanthomonas oryzae pv. oryzae
Damage toplants
 wiltingof seedlings
 yellowingand drying of leaves
 reducedyield
Economic importance
 Bacterialblight isone of themost seriousdiseasesof rice
 Yield loss due to bacterialblight can be as much as 70%
whensusceptiblevarieties are grown,inenvironments
favorable to thedisease
 Whenplantsareinfectedatbooting stage,bacterialblight
does not affectyield but resultsin poor qualitygrains and
a highproportionof broken kernels
 In India,causingyield losses from6% to60%

8. Symptoms
 Initiallywatersoaked,elongateddull greenishor yellow spot (5-10mm)
appear atthe tipor margins of theleaf
 Graduallythespots increasein sizeforminglinear,strawcoloredor
yellow-orangestripeson leaf blades orleaftips or blightedarea on one
orboth margins of leaves. The inner marginof the lesioniswavy,
irregularor ragged
 The stripesmay coalescetocover the entireleafblade
 Drops of bacterialooze orexudatesmay be observed in the morningon
young lesions
 Severely infectedfieldlook like as itwasburnt by fire.

9. Dried up
bacterial
ooze
Bacterial
ooze
Severelyinfectedfield
looklikeasburntbyfire
linear,strawcolored
or yellow-orange
stripesonleaf
blades

10. Factors favoring disease development
 presenceofweeds
 presenceof rice stubblesand ratoonsof infectedplants
 presenceof bacteriainthe rice paddy and irrigationcanals
 warmtemperature(25−34°C),high humidity(above 70%),
rainand deepwater
 over fertilization( excesssilica and magnesium)
 Potassiumandphosphorus deficiency
 handling of seedlingsat transplanting

11. Disease cycle

12. Control measures
 Practicingfieldsanitationsuchas removingweedhosts,rice straws,
ratoons,and volunteer seedlings
 Collectseeds fromonly healthycrop
 Practicebalancefertilization
 providing good drainage during severe flooding
 properplant spacingarerecommended
 Dry the diseasedfieldandallow tocrackbeforeirrigating
 Use resistantvariety, such as IR-20,IR-22,BR-14,BR-11,etc
 Seeds treatedwithAgrimycin @ 0.025 % solutionfor12hrs before sowing
 Applicationof bleachingpowder@15kg/hain the field
 Applicationof Bactroban20WP@ 500g/ha in the field

13. Bacterial leaf streak
CO: Xanthomonas oryzae pv. oryzicola
Damage to plants
 browningand drying of leaves
 reducedgrainweightdue toloss of photosynthetic area
Economic importance
 BacterialleafstreakiswidelydistributedinTaiwan,southernChina,
SoutheastAsiancountries,India,and WestAfrica
 Lossesashigh as32.3%grainweightdue toBLS werereported
 Basedon reported,yield loss causedbyBLS can range from8−17%in
thewetseason,and 1−3% in the dryseason

14. Symptoms
 Symptoms initiallyappearas small,water-soaked,linearlesions
betweenleaf veins
 Thesestreaksareinitiallydarkgreenandlaterbecome
light browntoyellowishgray
 The lesionsare translucentwhenheld againstthe light
 Entire leaves may become brownand diewhen
thediseaseis very severe
 Underhumid conditions,yellow dropletsof bacterialooze,which
containmassesof bacterialcells,observed on the surfaceof leaves

15. lightbrowntoyellowish
graylinearstreakonleaf

16. Factors favoring disease development
 presenceof the bacteriaon leaves andin thewateror those
surviving in the debris leftafterharvest
 high temperature(above 340C)andhigh humidity
 earlystageof plantingfrommaximum tilleringtopanicleinitiation

17. Disease cycle

18. Control measures
Same as BLB

19. Tungro of rice
 Tungrovirus disease is transmittedby leafhoppers,wherein the most
efficientvector is thegreenleafhopper,Nephotettixvirescens
 The diseasecomplexisassociatedwithrice tungro baciliformvirus
(RTBV)and rice tungrosphericalvirus (RTSV)
 RTBV cannot be transmittedby leafhoppersunless RTSV is present
 Insectscouldacquire the virus fromany partof the infectedplant.After
acquiringthevirus, thevector canimmediatelytransmittotheplants
Damage to plants
 leaf discoloration
 sterile or partially filled grains

20. Economic importance
 Tungro is one of the mostdamaging anddestructive diseases
of riceincountriesin SoutheastAsia
 Plant infectedwiththevirus at the earlycropgrowthstage
could have as high as 100%yield loss in severe cases
 The damage causedby the diseasedepends on--------
 the variety used,
 the plant stagewheninfectionoccurs
 the virus particles,and
 the environmentalconditions

21. Symptoms
 Plants affectedby tungro exhibitstuntingand reducedtillering
 The leaves become yellow or orange-yellow,may alsohave
rust-coloredspots
 Discolorationbegins fromleaf tipandextendsdowntothe blade
orthe lowerleafportion
 Delayed flowering,paniclessmalland not completelyexerted
 Mostpanicles sterileor partiallyfilledgrains

22. yellow ororange-yellow
leaves withrust-colored spots
Plantsaffectedbytungro
exhibitstunting
Greenleafhopper
Tungroaffected
ricefield

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. Transmissioncycle of tungrodisease(non-persistenttype) of rice

25. Control measures
 Eliminationofweedsand diseasedplants
 Adjustingthedate of plantingis recommended
 Plantingof resistantvarieties againsttungrovirus diseaseeg.
Segadis,Pata,Mala,Brisail,BR-5,BR-8,Nizersail,etc
 DestroyGLH throughlight trapping
 Controltheincidence of GLH by Malaton57 EC or Fyfanon 57EC or
Hilthion57EC or Sumady 57EC or Malason57EC orMB Malathion
57EC orAnthion 57EC or Guruthion57Ecor Maladion57EC @
2ml/litofwaterat 12-15days interval for2-3 timesin thefield

26. Grassy stunt of rice
CA: Rice grassy stunt virus (RGSV)
Transmitted by the brown planthopper (Nilaparvata lugens)
Damage to plants
 reduces yields by inhibiting panicle production
Economic importance
 The grassystuntvirus is not awidespreadproblem
 It became a serious problemduringbrownplanthopperoutbreaks
 Duringsporadic outbreaks,itcan causeserious damage in limitedareas
 Yield lossishigherwheninfectionoccursearlyin theseason

27. Symptoms
 Diseasedhills are severely stuntedwithexcessivetilleringand a very
upright growthhabit
 Diseasedhills has a grassyand rosetteappearance
 Leaves short,narrow,andyellowishgreenwithnumerous smallrusty
spots orpatches,whichformblotches
 Retentionof greencolorationof the leaves afterapplicationof sufficient
nitrogenousfertilizers
 Infectedplants usually survive untilmaturity,but produce no panicles
 The symptom develops 10-20days afterinfection

28. Diseasedhillsare
severely stuntedwith
excessive tillering,
veryuprightgrowth
habitandgrassy&
rosetteappearance
Brownplanthopper
short,narrow,
andyellowish
greenLeaves

29. Factors favoring disease development
 Infectedstubble and volunteerrice
 availabilityof the vector
 allgrowthstagesespeciallytilleringstageof the rice crop

30. Transmissioncycle of grassystuntdiseases(persistenttype) ofrice

31. Control measures
 Eliminationofweedsand diseasedplants
 Adjusting thedateof plantingisrecommended
 Plantingof resistantvarieties againstBPH likeIR26,IR64,IR36,IR56,IR72
 Controltheincidence of BPH by Hilthion57EC orMalasun57EC or
Razthion57EC orAshation57EC orMapathion57EC or Quiathion57EC or
Sumady 57EC or Malason57EC orMB Malathion57 EC orAnthion57EC
or Guruthion57Ec or Maladion57EC @ 2ml/litofwaterat 12-15days
intervalfor2-3 timesin thefield

32. Ufra of rice
CO: Ditylenchus angustus
 UfraDiseasea diseaseof deepwaterrice causedby feedingdamage
of the nematodeDitylenchusangustus
 Normally, the diseaseis observed in deepwaterrice growingareas
such as Barisal,Dhaka,Sirajganj,Faridpur,Jessore,Khulna,
Noakhali,PatuakhaliandSylhet districts
 The ufranematodefeeds ectoparasiticallyon the innersurfaceof
unmergedleaves, sheaths,buds, anddeveloping panicles
 In Bangladesh,irrigatedor deepwaterriceusuallystartsshowing
ufrasymptoms fromlate July orAugust.Croploss estimateswere
17-57%
 The symptoms of ufradiseasearenoticedat
threegrowthstagesof rice plant
 Seedlingufra / ufra-I
 Thor ufra/ swollenufra/ ufra-II
 Pucca ufra / ripeufra/ ufra-III

33. Symptoms (Seedling ufra)
 Splash ofwhitepatchesappearon the growingleaves
and leafbases of rice
The whitepatchesturnintobrowndiscoloration
 Severely infectedleaves becomeswitherand die
Splashofwhite
patches on the
growing leaves
and leaf bases
ofrice

34. Symptoms (Thor ufra)
 The earremainswithinthe sheath,swellsup but failstoemerge
 Ultimatelythesheath enclosing the swollenearbecomesspindleshaped
 The panicleby this timebecomes twistedand failsto produce grains or
produce sterilegrains.
Twistedanddistorted
leaves &paniclesand
failstoproducegrains

35. Symptoms (Pucca ufra)
 The earemerges fromthe leafsheath(Flagleaf)
 The peduncle andspikeletsbecome dark browntoblack
 The lowerpartof theeargives aburnt out appearanceand
produces few grains of poorqualitynearthetip
lowerpartoftheear
gives aburntout
appearanceand
producesfewgrains
ofpoorquality near
thetip

36. Factors favoring disease development
 High humidity during growing stages
 Temperature 28-300C (Development and
infection is favored)

37. Control measures
 Burnthe stubblesand debris in thefield
 Rotationof crops
 Heatthe soilupto a deathof 3-4inch and uniformly
 Completelydrying fieldswhentheyare fallow
 Plough the land deepand expose it fordrying
 Cultivate resistantvarieties such as Raida,Bajail-65,Digha.
 Apply of Furadan 5Gor Edfuran5Gor Brifur5Gor Cemifuran5Gor
Promofuran 5G or Calfuran5G orDinafuran5G @ 20kg/ha

38. Root knot of rice
CO: Meloidogyne graminicola
 Root knot diseaseof rice is widelydistributedin ricegrowing
areasof theworld,viz., India,U.S.A., SouthAmerica,Burma,
Vietnam,Taiwan,Indonesia,Philippines,Laos, Thailand
BangladeshandPakistan
 M. graminicolais a damaging parasiteon upland, lowlandand
deepwaterrice
 The riceroot-knotnematode is consideredone of the limiting
factorsin riceproductionin allrice ecosystems. 20%losses
have beenreportedunder intermittentflooding,30%in semi
deepwaterand70% undersaturatedcondition
 16 to20% yield loss causedbyM. graminicolainlow land
rainfedrice inBangladesh

39. Symptoms
 The above ground symptoms of root knot diseaseof riceare
yellowing,dwarfing,drying of leaves andwilting
 Infectedplants failtorespond toirrigationand fertilizer
 below ground symptoms includeformationof hook,spindleor
club shapedgalls on the rootssystem of rice plants

40. Galls on
the roots

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

42. What it does
 Infective secondstagejuvenile of M. graminicolapenetrates
throughthe root tipsand takesabout a minimum of 41 hours
 Femalesdevelop withintheroot and eggs are laid in thecortex
 Gallsare formedin 72 hours
 The juveniles or immaturesremain in the maternalgallor migrate
intercellularlythroughthe aerenchymatous tissuesof the cortex
tonew feedingsiteswithinthesame root.

43.  Continuousflooding
 Raisingthe riceseedlings in floodedsoils
 Croprotation
 Use resistantvarieties
 Usenematicidalcompounds:volatile (fumigants)and nonvolatile
nematicidesapplied as soildrenches
 TreatseedswithEPN and carbofuran
 Apply of Furadan 5Gor Edfuran5G orBrifur5G orCemifuran5G or
Promofuran 5Gor Calfuran5Gor Dinafuran5G @20kg/ha
Control measures

44. THANKS TO ALL