🥜Oilseed & Pulse Crop Diseases — Pathogens, Symptoms, and Management

From Field to Lab — When Oilseeds and Pulses Fall Sick

India is the world’s largest producer of pulses and a major oilseed grower. Groundnut fields in Gujarat ravaged by Tikka leaf spot can lose 50% of their leaf area. Mustard crops in Rajasthan showing swollen, sterile “stag head” formations are suffering from white rust (Albugo candida). Chickpea plants that wilt and die in patches indicate Fusarium wilt — a soil-borne menace that can persist for years. Understanding these diseases is critical for both farm management and competitive exams.

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Groundnut Diseases

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1. Tikka Leaf Spot (Early + Late Leaf Spot)

Symptoms:

• Small dark brown spots and premature leaf shedding
• Both pathogens can co-infect the same plant

Management:

• Seed treatment with Carbendazim or Thiram @ 2 g/kg
• Spray Carbendazim 500 g or Mancozeb 2 kg or Chlorothalonil 2 kg/ha; repeat after 15 days if necessary

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2. Collar Rot / Seedling Blight / Crown Rot — Aspergillus niger and A. pulverulentum

Phase 1 — Pre-emergence rot:

• Seeds attacked by soil-borne conidia causing rotting of seeds
• Seeds covered with black masses of spores; internal tissues become soft and watery

Phase 2 — Post-emergence rot:

• Pathogen attacks emerging seedlings causing circular brown spots on cotyledons
• Affected portion becomes soft and rotten, resulting in collapse of the seedling

Phase 3 — Crown rot (in adult plants):

• Large lesions develop on stem below soil and spread upwards along branches
• Causes drooping of leaves and wilting of plant

Management:

• Crop rotation
• Destruction of plant debris
• Remove and destroy previous season’s infested crop debris
• Seed treatment with Trichoderma viride / T. harzianum @ 4 g/kg
• Soil application of Trichoderma viride / T. harzianum at 2.5 kg/ha with organic amendments (castor cake or neem cake or mustard cake @ 500 kg/ha)

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3. Bud Necrosis Disease — Groundnut bud necrosis virus (GBNV — Tospo virus)

Symptoms:

• First symptoms visible 2-6 weeks after infection as ring spots on leaves
• Newly emerging leaves are small, rounded or pinched inwards and rugose with varying patterns of mottling and minute ring spots
• Necrotic spots and irregularly shaped lesions develop on leaves and petioles
• Stem also exhibits necrotic streaks

Management:

• Control thrips vector with systemic insecticides
• Remove infected plants early
• Use resistant varieties

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Minor Groundnut Disease

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Rapeseed & Mustard Diseases

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1. White Rust / White Blister — Albugo candida

Symptoms:

• White or yellow pustules with variable sizes and shapes on the lower surface of leaves
• Infection covers all parts except roots
• Entire inflorescence replaced by swollen sterile structure called “Stag head”

Management:

• Seed treatment with Metalaxyl (Apron 35 SD) @ 6 g/kg
• Spray Mancozeb (0.2%) or Ridomil MZ (0.25%)
• Use resistant varieties

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2. Alternaria Blight — Alternaria brassicae

Symptoms:

• Concentric black spots on leaves, stem, and pods
• Spots have characteristic target-board appearance

Management:

• Spray Mancozeb (0.2%) or Iprodione (0.2%)
• Use resistant/tolerant varieties
• Crop rotation

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3. Downy Mildew — Peronospora brassicae

Symptoms:

• Yellow and irregular spots on upper surface with white growth on under surface of leaves
• Malformed inflorescence

Management:

• Seed treatment with Metalaxyl
• Spray Ridomil MZ (0.25%)
• Ensure proper plant spacing for air circulation

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4. Clubroot — Plasmodiophora brassicae

Symptoms:

• Roots develop abnormal swellings or “clubs”
• Plants show wilting, stunting, and yellowing

Management:

• Liming of acidic soils to raise pH above 7.2
• Long crop rotation (5-7 years)
• Use resistant varieties

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Sunflower Diseases

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1. Root Rot / Charcoal Rot — Rhizoctonia bataticola

Symptoms:

• Pathogen is seed-borne; causes seedling blight and collar rot in initial stages
• Infected plants show drooping of leaves and death occurs in patches
• Bark of lower stem and roots shreds; associated with large number of sclerotia

Management:

• Seed treatment with Carbendazim or Thiram
• Crop rotation with non-host crops
• Deep summer ploughing

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2. Alternaria Blight

Symptoms:

• Dark brown to black spots with concentric rings on leaves
• Severe defoliation in humid conditions

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3. Rust and Downy Mildew

• Rust and downy mildew also affect sunflower
• Manage with appropriate fungicide sprays and resistant varieties

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Red Gram / Pigeon Pea Diseases

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1. Wilt — Fusarium udum

Symptoms:

• Plants show wilting, yellowing, and drying of leaves
• Browning of vascular tissues visible when stem is split open
• Can occur at any growth stage

Management:

• Use resistant varieties (e.g., Maruti, Asha-ICPL 87119)
• Seed treatment with Trichoderma viride @ 4 g/kg
• Crop rotation with cereals

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2. Sterility Mosaic Disease (SMD) — Pigeonpea sterility mosaic virus (PPSMV)

Symptoms:

• Characterised by bushy and pale green appearance of plants
• Excessive vegetative growth, stunting, prominent mosaic on leaves, and reduction in leaf size
• Complete or partial cessation of flowering leads to sterility

Management:

• Control eriophyid mite vector with wettable sulphur or Dicofol sprays
• Use resistant varieties
• Remove and destroy infected plants

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Soybean Diseases

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1. Yellow Mosaic — Yellow mosaic virus

Symptoms:

• Conspicuous systemic bright yellow mottling of leaves
• Infected plants show reduced pod formation

Management:

• Control whitefly with systemic insecticides (Imidacloprid, Thiamethoxam)
• Use resistant varieties
• Early sowing to escape peak whitefly population

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2. Charcoal Rot — Rhizoctonia bataticola

Symptoms:

• Reddish black to brown necrotic lesion at crown portion

Management:

• Seed treatment with Carbendazim
• Summer ploughing and crop rotation

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3. Rust and Purple Seed Stain

• Soybean rust is an important foliar disease
• Purple seed stain affects seed quality and marketability

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Green Gram Diseases

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1. Yellow Mosaic — Yellow mosaic virus

Symptoms:

• Bright yellow mottling on leaves, transmitted by whitefly (Bemisia tabaci)
• Severe yield loss when infection occurs early

Management:

• Spray systemic insecticides to control whitefly
• Use resistant varieties (e.g., Pusa Vishal, SML 668)

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2. Cercospora Leaf Spot

Symptoms:

• Circular to irregular brown spots on leaves
• Premature defoliation in severe cases

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Minor Green Gram Diseases

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Bengal Gram / Chickpea Diseases

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1. Wilt — Fusarium oxysporum f.sp. ciceri

Symptoms:

• Plants show drooping and yellowing of leaves
• Browning of vascular tissues
• Can cause total crop failure in susceptible varieties

Management:

• Use resistant varieties
• Seed treatment with Carbendazim + Thiram (1:1) @ 2 g/kg or Trichoderma viride @ 4 g/kg
• Crop rotation with non-host crops

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2. Ascochyta Blight — Ascochyta rabiei

Symptoms:

• Circular brown lesions on leaves, stems, and pods
• Concentric rings visible on pods
• Severe in cool, wet weather

Management:

• Seed treatment with Thiram or Captan
• Spray Mancozeb (0.2%) or Chlorothalonil
• Use resistant varieties

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3. Botrytis Grey Mould — Botrytis cinerea

Symptoms:

• Grey mouldy growth on flowers, pods, and stems
• Favoured by dense canopy and high humidity

Management:

• Avoid dense planting
• Spray Carbendazim (0.1%) or Iprodione
• Use tolerant varieties

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Other Bengal Gram Diseases

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Sesame Diseases

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1. Phyllody — Phytoplasma (MLO)

Symptoms:

• Affected plants are stunted
• Entire inflorescence is replaced by a growth consisting of green, short, twisted leaves closely arranged on the stem with very short internodes
• Floral parts converted into leaf-like structures (phyllody)

Management:

• Control leafhopper vector with systemic insecticides
• Remove and destroy infected plants
• Early sowing to avoid peak leafhopper activity

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2. Leaf Spot

Symptoms:

• Circular to irregular spots on leaves
• Premature defoliation

Management:

• Spray Mancozeb (0.2%) or Carbendazim (0.1%)
• Use clean, disease-free seed

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Summary Cheat Sheet

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Quick Revision Table

Complete Oilseed & Pulse Disease Summary

Crop	Disease	Pathogen	Key Exam Fact
Groundnut	Tikka (Early leaf spot)	Cercospora arachidicola	Irregular, larger spots
Groundnut	Tikka (Late leaf spot)	Cercosporidium personata	Regular spots, less than 0.6 cm
Groundnut	Collar rot	Aspergillus niger	Three phases: pre-emergence, post-emergence, crown rot
Groundnut	Bud necrosis	GBNV (Tospo virus)	Vector: Thrips
Mustard	White rust	Albugo candida	Stag head formation
Mustard	Alternaria blight	Alternaria brassicae	Concentric black spots
Mustard	Downy mildew	Peronospora brassicae	White growth on lower leaf surface
Mustard	Clubroot	Plasmodiophora brassicae	Root swelling, favoured by acidic soil
Sunflower	Charcoal rot	Rhizoctonia bataticola	Seedling blight, sclerotia in stem
Pigeon pea	Wilt	Fusarium udum	Specific to pigeon pea
Pigeon pea	Sterility mosaic	PPSMV	Vector: Eriophyid mite
Soybean	Yellow mosaic	YMV	Vector: Whitefly (Bemisia tabaci)
Green gram	Yellow mosaic	YMV	Vector: Whitefly
Chickpea	Wilt	F. oxysporum f.sp. ciceri	Forma specialis specific to chickpea
Chickpea	Ascochyta blight	Ascochyta rabiei	Concentric rings on pods
Chickpea	Grey mould	Botrytis cinerea	Dense canopy + humidity
Sesame	Phyllody	Phytoplasma (MLO)	Vector: Leafhopper (Orosius albicinctus)