The document discusses several rice diseases that affect Bangladesh, including leaf scald, bacterial leaf blight, bacterial leaf streak, tungro virus, and grassy stunt virus. Leaf scald causes scalded lesions on rice leaves and can result in 20-30% yield losses. Bacterial leaf blight forms water-soaked lesions that enlarge to cause yellow stripes, and it is one of the most serious rice diseases, capable of 70% yield loss. Tungro virus stunts rice plants, causes discolored leaves, and sterile panicles, resulting in complete yield loss in severe cases. Control methods for these diseases include removing weeds, crop residues, and infected plants, using resistant varieties, seed treatment, and targeted

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