📈 Diseases of Chickpea and Pigeonpea

Chickpea (Cicer arietinum) and pigeonpea (Cajanus cajan) are the two most important pulse crops of India. Both are affected by devastating wilt and blight diseases that cause significant economic losses.

Diseases of Chickpea

Fusarium Wilt

Causal Organism: Fusarium oxysporum f. sp. ciceri

This is the most important disease of chickpea in India, causing yield losses of 10-90%.

Symptoms:

• Sudden drooping and yellowing of the entire plant
• Browning of vascular tissue visible on splitting the stem or root — the diagnostic feature
• Wilted plants dry up with leaves attached (do not shed leaves)
• Seedlings may show wilt within 25 days of sowing (early wilt) or at flowering (late wilt)

Disease Cycle: The pathogen is soil-borne and survives as chlamydospores in soil for 6+ years. It infects through roots and colonizes the xylem vessels, blocking water transport.

Eight races of the pathogen have been identified (Race 1, 2, 3, 4, 5, 6, 7, 8), making resistance breeding complex.

Management:

• Grow resistant varieties (e.g., JG 62, WR 315, Avrodhi)
• Seed treatment with Trichoderma viride (4 g/kg) + Carbendazim (2 g/kg)
• Long crop rotation (3-4 years) with cereals
• Soil application of Trichoderma + neem cake (150 kg/ha)

Ascochyta Blight

Causal Organism: Ascochyta rabiei (Teleomorph: Didymella rabiei)

Symptoms:

• Circular to elongated brown necrotic lesions with dark margins on leaves, stems, and pods
• Concentric rings of pycnidia (small black dots) visible in lesions
• Stem girdling causes breakage — entire branches may die
• Pod lesions lead to shrivelled, discoloured seeds

Favorable Conditions:

Management:

• Use disease-free certified seed
• Seed treatment with Thiram + Carbendazim (1:1 at 2.5 g/kg)
• Foliar spray of Mancozeb 75 WP (0.25%) at 10-day intervals
• Grow tolerant varieties and avoid very dense planting

Botrytis Grey Mold (BGM)

Causal Organism: Botrytis cinerea

Symptoms:

• Water-soaked lesions on stems, leaves, flowers, and pods
• Grey fluffy mold growth on affected parts under humid conditions
• Flower drop and pod rotting leading to 50-100% loss in severe cases

Management:

• Wide row spacing to improve air circulation
• Spray Carbendazim (0.1%) at flowering and podding stages
• Avoid excessive irrigation during flowering

Diseases of Pigeonpea

Fusarium Wilt

Causal Organism: Fusarium udum (syn. Fusarium oxysporum f. sp. udum)

Symptoms:

• Partial or complete wilting of the plant
• Purplish-brown streaking of xylem visible in longitudinal stem sections
• Leaves turn yellow and droop but remain attached
• Plants may show wilt at seedling stage or at flowering/podding

Disease Cycle: Pathogen survives in soil as chlamydospores for several years. Primary infection is through roots.

Management:

• Resistant varieties (e.g., Maruti, ICP 8863, ICPL 87119)
• Seed treatment with Trichoderma (4 g/kg) + Carbendazim (2 g/kg)
• Mixed cropping with sorghum acts as a barrier
• Crop rotation with cereals for 3+ years

Sterility Mosaic Disease (SMD)

Causal Organism: Pigeonpea Sterility Mosaic Virus (PPSMV) — an emaravirus

Vector: Eriophyid mite (Aceria cajani)

Symptoms:

• Leaves become small, pale green, and show mosaic mottling
• Excessive vegetative growth with bushy appearance
• Complete sterility — no flowers or pods form
• Partial mosaic shows mild symptoms with some pod set

Management:

• Grow resistant varieties (e.g., ICP 7035, Bahar)
• Control mite vector with Wettable sulphur (0.3%) or Fenazaquin
• Rogue out infected plants early
• Avoid planting near old pigeonpea fields

Phytophthora Blight

Causal Organism: Phytophthora cajani

Symptoms:

• Water-soaked lesions on stems near soil level, girdling the plant
• Rapid wilting and death of plants, especially in waterlogged areas
• Dark brown stem lesions with sharp margins

Management:

• Improve drainage; avoid waterlogged conditions
• Seed treatment with Metalaxyl (6 g/kg)
• Resistant varieties and raised-bed planting

Summary Cheat Sheet