documents/Maize_Diseases_Bangladesh.txt

COMMON MAIZE (VUTTA) DISEASES & PESTS IN BANGLADESH
Farmer's Guide: Symptoms, Prevention & Control

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1. FALL ARMYWORM (FAW) - Spodoptera frugiperda
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Type: Insect pest (not a disease)

SYMPTOMS
- Semi-transparent "window pane" patches on leaves (early larval stage, seedling to early growth)
- Holes in leaves and in the central whorl ("Infested Whorl")
- Larval droppings (frass) accumulate in the whorl
- Damaged, hollowed-out, or destroyed cobs with frass inside, from silking onward
- Large larvae can defoliate a whole plant in a single night

PREVENTION & CONTROL
- Plant early with the first rains; avoid staggered planting dates
- Use balanced fertilizer for healthy, vigorous plants
- Keep field borders free of weedy grasses
- Scout fields weekly from seedling emergence; check 10-20 plants at 5 spots per field
- Action point: spray if more than 20% of plants damaged at knee-high stage, or more than 40% of whorls damaged at shoulder-high stage; do not spray at tasseling/silking
- Hand-pick and destroy egg masses and larvae
- Use pheromone traps (35-40/ha) for monitoring and mass trapping
- Apply SNPV biopesticide (0.2 g/L water) every 10 days, 2-3 times
- Release natural enemies such as Bracon hebetor wasps where available
- Avoid broad-spectrum insecticides that kill natural enemies

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2. TURCICUM LEAF BLIGHT / NORTHERN CORN LEAF BLIGHT
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Causal organism: Exserohilum turcicum (fungus)

SYMPTOMS
- Long, elliptical (cigar-shaped), greyish-green to tan lesions on leaves
- Lesions run parallel to leaf veins and can merge, causing large areas of leaf to die (blight)
- Severe infection can destroy most of the leaf area, reducing grain fill
- Common in humid weather with moderate temperatures

PREVENTION & CONTROL
- Grow resistant/tolerant maize varieties
- Rotate maize with non-host crops (e.g., legumes)
- Remove and destroy infected crop debris after harvest
- Avoid overly dense planting; ensure good air circulation
- Apply a recommended fungicide (e.g., Mancozeb or Propiconazole-based) if disease appears early and weather stays humid

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3. COMMON RUST OF MAIZE
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Causal organism: Puccinia sorghi (fungus)

SYMPTOMS
- Small, round to elongated, reddish-brown pustules scattered on both leaf surfaces
- Pustules rupture and release powdery rust-colored spores
- In severe cases, leaves turn yellow and dry prematurely
- More common in cooler, humid weather

PREVENTION & CONTROL
- Use rust-tolerant varieties where available
- Avoid very early or very late planting that exposes crop to prolonged cool, humid weather
- Remove volunteer maize plants and crop debris after harvest
- Apply fungicide if rust appears early and is spreading rapidly, especially on susceptible varieties

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4. DOWNY MILDEW OF MAIZE
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Causal organism: Peronosclerospora species (fungus-like organism)

SYMPTOMS
- Young plants show pale green to yellow (chlorotic) streaking on leaves, running parallel to veins
- Leaves may appear stunted, narrow, and twisted
- White to greyish, downy fungal growth can appear on the underside of leaves in humid/wet conditions, especially in early morning
- Severely infected plants are stunted and often fail to produce normal cobs

PREVENTION & CONTROL
- Use certified, disease-free seed; treat seed with a recommended fungicide (e.g., metalaxyl-based) before sowing
- Avoid planting in low-lying, waterlogged fields
- Remove and destroy infected plants early (roguing) to reduce spread
- Practice crop rotation with non-cereal crops
- Ensure good field drainage

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5. BANDED LEAF AND SHEATH BLIGHT (BLSB)
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Causal organism: Rhizoctonia solani f. sp. sasakii (fungus)

SYMPTOMS
- Irregular, greyish-green, water-soaked bands/patches on leaf sheaths, starting near the base of the plant
- Bands spread upward to leaves and can reach the cob under humid conditions
- Infected sheaths and leaves rot and turn straw-colored
- Cobs may also be infected, showing rotting and poor grain fill
- Common in dense plantings with high humidity

PREVENTION & CONTROL
- Avoid excessive plant density; ensure proper spacing for airflow
- Avoid waterlogging; ensure good field drainage
- Remove and destroy infected crop residues after harvest
- Rotate with non-host crops
- Apply a recommended fungicide at the base of plants if disease appears early in humid seasons

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6. STALK ROT (Fusarium / Bacterial Stalk Rot)
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Causal organism: Fusarium species (fungus) or bacteria, often following stress/damage

SYMPTOMS
- Lower stalk becomes soft, discolored (brown to black), and shows a rotten smell (in bacterial stalk rot)
- Pith inside the stalk disintegrates, leaving the stalk hollow and weak
- Plants wilt suddenly, and stalks can easily break or lodge (fall over)
- Premature plant death, often near maturity

PREVENTION & CONTROL
- Avoid excess nitrogen and imbalanced fertilization
- Ensure adequate potassium fertilization, which strengthens stalks
- Avoid water stress and waterlogging; maintain balanced irrigation
- Control stem-boring insects, since wounds allow the pathogen to enter
- Harvest promptly once mature to avoid stalk rot–related lodging losses
- Practice crop rotation and residue destruction after harvest

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GENERAL TIPS FOR ALL MAIZE DISEASES & PESTS
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- Start with healthy, certified seed; treat seed before sowing when recommended
- Follow proper spacing and recommended seeding rate to reduce humidity buildup within the canopy
- Balance fertilizer application; avoid excess nitrogen, ensure adequate potassium
- Keep fields and field bunds free of weeds and volunteer plants
- Rotate maize with non-cereal crops such as legumes where possible
- Scout fields weekly, especially during humid or rainy weather and around key growth stages
- Remove and destroy infected crop debris after harvest to reduce carryover of disease
- When applying any pesticide or fungicide, wear gloves and a mask, and follow label instructions
- Contact your nearest Department of Agricultural Extension (DAE) office or the Bangladesh Wheat and Maize Research Institute for the latest recommended varieties and chemicals