documents/Wheat_Diseases_Bangladesh.txt

COMMON WHEAT (GOM) DISEASES IN BANGLADESH
Farmer's Guide: Symptoms, Prevention & Control

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1. WHEAT BLAST (Gomer Blast Rog)
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Causal organism: Fungus (Magnaporthe oryzae Triticum pathotype)

SYMPTOMS
- Wheat spike (head) turns white at the point of infection, spreading quickly in warm, humid weather
- Blackish-grey spots appear where the spike is infected; upper part turns white
- If infection starts at the base of the spike, the whole spike dries and turns white
- Grains become shriveled, discolored, and unfit for use
- On leaves: small, water-soaked, eye-shaped grey spots
- Most damaging around heading to flowering stage

HOW IT SPREADS
- Spreads through infected seed
- Favored by 12-24 hours of leaf/spike wetness plus temperatures of 18-25°C
- Survives on grassy weeds between seasons

PREVENTION & CONTROL
- Use certified, disease-free seed
- Grow blast-tolerant varieties (BARI Gom 28, 30, 32) or resistant variety (BARI Gom 33)
- Sow between November 15-30 to avoid rain/high heat during heading
- Treat seed before sowing with Provax 200 WP or Vitavax 200 FF (3 g or 3 ml per kg seed)
- Keep fields and bunds weed-free
- Spray fungicide (Nativo 75 WG or Amistar Top 325 SC) once at heading and again 12-15 days later
- Wear gloves and a mask when spraying

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2. LEAF SPOT / SPOT BLOTCH (Pata Dhosa Rog)
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Causal organism: Bipolaris sorokiniana (fungus)

SYMPTOMS
- Small, elongated to oval, brown to blackish spots scattered on leaves
- As spots mature, centers turn light brown/tan with a dark brown margin
- Large, well-developed spots produce heavy spore growth and can cover most of the leaf
- Severely affected leaves dry up completely (blighted)
- Infection on stem and nodes can cause the plant to lodge (fall over)
- Ear/spikelets can also be infected under favorable conditions; grains become discolored, shriveled

PREVENTION & CONTROL
- Use disease-free, certified seed; treat seed with fungicide before sowing
- Practice crop rotation with non-cereal crops
- Avoid excess nitrogen; ensure balanced fertilization
- Remove and destroy infected crop debris after harvest
- Spray a recommended fungicide (e.g., Tebuconazole or Propiconazole based) if disease appears early, especially in humid weather
- Grow tolerant varieties where available

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3. STEM RUST / BLACK RUST (Kando Marchha Rog)
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Causal organism: Puccinia graminis f. sp. tritici (fungus)

SYMPTOMS
- Appears later in crop growth, usually after heading
- Elongated, reddish-brown (rust-colored) pustules erupt on stem, leaf sheath, and leaves
- Pustules burst, releasing powdery brown spores that spread to reinfect the crop
- As the plant matures, pustules turn dark brown to black (hence "black rust")
- Torn, tattered appearance of leaf/stem tissue where pustules erupt
- Can cause significant yield loss if infection starts early and weather stays warm and humid

HOW IT SPREADS
- Spores are carried long distances by wind
- Favored by warm daytime temperatures (25-30°C), wet weather, and prolonged dew
- Needs living plant tissue to survive; volunteer wheat/barley plants after harvest can carry it over

PREVENTION & CONTROL
- Grow rust-resistant wheat varieties
- Sow early (within recommended window) to avoid infection during grain-filling
- Destroy volunteer wheat/barley plants after harvest
- Monitor fields regularly after heading, especially in warm, humid weather
- Apply a recommended fungicide preventatively if rust is forecasted or first pustules are seen, targeting the flag leaf stage
- Avoid excess nitrogen fertilizer, which promotes lush, susceptible growth

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4. POWDERY MILDEW (Gura Sada Rog)
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Causal organism: Blumeria (Erysiphe) graminis f. sp. tritici (fungus)

SYMPTOMS
- Small yellow spots appear on leaves 5-7 days after infection
- White, fluffy/powdery fungal growth develops on these spots (leaves, stem, sometimes head)
- Infected leaves yellow and die early
- Later, small black specks (fungal fruiting bodies) appear on old infected tissue near plant base
- Most common in lush, early-sown, nitrogen-rich crops during tillering stage
- Usually does not persist much beyond ear emergence

PREVENTION & CONTROL
- Avoid highly susceptible varieties; choose tolerant ones
- Use recommended seed rate (about 100 kg/ha) — avoid overly thick/lush stands
- Avoid excess nitrogen; apply potassium fertilizer as recommended instead
- Remove volunteer wheat plants and crop debris from the field after harvest
- Maintain regular, balanced irrigation (avoid excess moisture and humidity buildup)
- Apply a sulfur-based or triazole fungicide if infection is severe early in the season

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GENERAL TIPS FOR ALL WHEAT DISEASES
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- Always start with healthy, certified seed and treat seed before sowing
- Follow recommended sowing time and seed rate for your area
- Avoid excess nitrogen fertilizer; balance with phosphorus and potassium
- Keep fields and field bunds free of weeds and volunteer plants
- Rotate crops where possible instead of continuous wheat
- Scout fields regularly, especially during humid or rainy weather
- When spraying fungicide, always wear gloves and a mask, and follow label instructions
- Contact your nearest agricultural extension office or BARI Wheat Research Centre for the latest recommended varieties and chemicals