The document describes several rice diseases, their causal organisms, symptoms, and control methods. It discusses 16 fungal diseases, 5 bacterial diseases, 5 viral diseases, 2 mycoplasma diseases, and 4 nemic diseases that affect rice. Two diseases, brown spot and narrow brown spot, are then described in more detail including their symptoms, factors influencing disease development, disease cycles, and control measures such as use of resistant varieties, crop residue burning, and fungicide application. The document provides an overview of the many diseases that impact rice production worldwide.

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

2. RICE DISEASES
Name of the disease Causal organism
Brown spot Bipolaris oryzae
Blast Pyricularia oryzae
Narrow brown spot Cercospora oryzae
Leaf scald Rhynchosporium oryzae
Stem rot Sclerotium oryzae
Bakanae and foot rot Fusarium moniliforme
Sheath blight Rhizoctonia solani
Sheath rot Sarocladium oryzae
Stack burn Alternaria padwickii
False smut Ustilaginoidea virens
Damping off Fusarium sp., Pythium sp.
Collar rot Ascochyta oryzae
Downy mildew Sclerophthora macrospora
Leaf smut Entyloma oryzae
Rust Puccinia graminis f. sp. oryzae
Fungal diseases

3. Bacterial Diseases
Name of the disease Causal organism
Bacterial leaf blight Xanthomonas oryzae pv. oryzae
Bacterial leaf streak Xanthomonas oryzae pv. oryzicola
Bacterial grain rot Burkholderia glumae
Bacterial sheath rot Pseudomonas syringae
Bacterial stripe Acidovorax avenae subsp. avenae
Nemic diseases
Name of the disease Causal organism
Ufra Ditylenchus angustus
White tip Aphelenchoides besseyi
Root knot Meloidogyne graminicola
Root rot Hirschmaniella oryzae

4. Viral diseases
 Tungro (vector: GLH)
 Stripe
 Hoja blancha
 Orange leaf
 Dwarf
 Mosaic
Mycoplasma diseases
 Yellow dwarf
 Grassy stunt (vector: BPH)

5. Rice diseases on foliage
 Brown spot
 Blast
 Narrow brown spot
 Leaf scald
 Downy mildew
 Leaf smut
 Stack burn
 Rust
 Bacterial leaf blight
 Bacterial leaf streak
Rice diseases on leaf sheath
 Sheath rot
 Sheath blight
 Bacterial sheath rot
Rice diseases on stem
 Stem rot
 Bakanae and foot rot
 Sheath blight
Rice diseases on seedling
 Damping off
 Seedling blight
 Seedling ufra
Rice diseases on root
 Root knot
 Root rot
 Bakanae and foot rot
Rice diseases on grains and
inflorescence
 False smut
 Black kernel, grain spotting,
grain discoloration
 Bacterial grain rot
 Pucca ufra
 White tip

6. Soil borne diseases
 Sheath rot
 Sheath blight
 Stem rot
 Bacterial sheath rot
 Damping off
 Seedling blight
 False smut
Air borne diseases
 Rust
 Downy mildew
 Leaf smut
Seed borne rice diseases
 Brown spot
 Blast
 Sheath rot
 Bacterial leaf blight
 Ufra
 White tip

7. Brown spot of rice
CO: Bipolaris oryzae
Damagetoplants
 seedlingmortality
 qualityandnumberofgrainsaffected
 The diseasecausesblight on seedlings,whicharegrownfrom
heavily infectedseeds,and cancause 10-58%seedlingmortality.
 It alsoaffectsthe qualityand the number of grains perpanicle
and reducesthe kernelweight.
 The reductionin yield canbe as high as 45%in severe infection
and 12%in moderateinfection.
 The diseasewasconsideredtobe themajor factorcontributing
tothe “GreatBengalFamine”in 1942 resultingto yield lossesof
50%to90%and caused the deathof 2 millionpeople.
Economic importance

8. Symptoms
 Infected seedlings have small, circular or oval, brownlesions,whichmay
girdle the coleoptileand cause distortionof the primary and secondaryleaves
(symptom is called seedlingblight).
 Infected seedlings become stuntedor die.
 Youngor under developed lesions on older leaves are small and circular, dark
brownor purplish brown.
 Afullydeveloped lesionon older leaves is oval, brownwithgray or whitish
center withreddish brown margin.
 When infectionis severe, the lesions may coalesce, killinglarge areas of
affected leaves.
 Infected grains withblack discolorationor withbrownlesions

9. Youngor under
developed lesions
on older leaves are
small and circular,
dark brownor
purplish brown
Afully developed
lesion on older
leaves is oval,
brownwithgray
or whitishcenter
withreddish
brownmargin
Infected grains with
black discolorationor
withbrownlesions
Conidia of B. oryzae

10. Factors favoring disease development
 presenceof infectedseeds,volunteer rice,ricedebris,and severalweeds
 poorly drainedor nutrientdeficientsoils (K,Mg,Mn & Silica deficiency)
 abnormalsoils,whichare deficientin nutrientelements(Nitrogendeficiency)
 temperatureranging from25-300C
 waterstressandhigh humidity
 continue rainfalland cloudiness
 maximumtilleringup tothe ripeningstagesof the crop

11. Disease cycle

12. Control measures
 Theuseofresistantvarieties
 Cropresiduesburning
 Adjustmentofplantingtime
 Properfertilization
 Goodwatermanagement
 Hotwaterseedtreatment(53-54°C)for10-12minutesbeforesowing
 Presoakingtheseedincoldwaterfor8hours
 SeedtreatmentwithFreshcozim 50wp@2.5g/kgseedsorProvax 200WP
@3g/kgseedsorVitaFlo200FF@5ml/kgseeds
 ApplicationofFreshcozim 50WPorProvax 200WP@2g/litofwater;
VitaFlo200FF orEdifen50EC@2ml/litofwater at15daysintervalfor2-3
timesinthefield

13. Narrow brown leaf spot
CO: Cercospora oryzae
Damage to plants
 premature death of leaves
 premature ripening of grains
 Prematuredeathofleaves andleafsheaths,prematureripening
ofkernelsandlodging ofplantsareobserved duringsevere infection
 Itdecreasesthemarketvalue ofthegrainsbecauseitcausesgrain
discolorationandchalkiness,and reducesthemillingrecovery
 40%lossisobserved duringsevere infection
Economic importance

14. Symptoms
 Short,narrow,ellipticaltolinearbrownlesions usuallyon leaf blades but
may alsooccuron leaf sheaths,pedicels,and glumes orrice hulls
 Lesions about 2-10mm long and 1 mmwide
 Lesions narrower,shorter,and darkerbrownon resistantvarieties
 Lesionswiderand lighterbrownwithgraynecroticcenterson susceptible
varieties
 Leaf necrosismay alsooccuron susceptiblevarieties
 Lesions occurin large numbers duringthe latergrowthstages

15. Short, narrow,
elliptical to
linear brown
lesions usually
on leaf blades

16. Factors favoring disease development
 presence of rice crops grown on problem soil
deficient in potassium
 temperature from 25-28° C
 susceptibility of the variety to the fungus
 late growth stages of the rice crop

17. Control measures
 Theuseofpotassiumandphosphorusfertilizers
 Plantingofearlymaturingcultivarsearlyinthegrowingseason
 Theuseofresistantvarieties
 Seedtreatment&spraying offungicidesinthefieldsameasbrown
spotofrice

18. THANKS TO ALL