Collar rot or seedling blight or crown rot: Aspergillus niger

Symptoms:
i. Pre-emergence rot:

• Rotting of seeds
• Seeds are covered with black masses of spores and internal tissues become soft and watery.

ii. Post-emergence rot:

• Circular brown spots on the cotyledons
• Brown discolored spots at collar region
• Collapse of seedling
• Collar region with profuse conidia
• Stem show shredding

iii. Crown rot:

• Mature plants show crown rot
• Large lesions on stem and spread upwards along the branches
• Drooping of leaves and wilting of plant

Seedling blight	Collar rot

Pathogen:

• Conidiophores: Septate, thick walled, hyaline or olive brown
• Vesicles: Globose and have two rows of hyaline phialides
• Conidial head: Dark brown to black with dark brown conidia in chains

Aspergillus niger

Favourable Conditions:

• Deep sowing of seeds
• High soil temperature (30-35⁰C)
• Low soil moisture

Mode of Spread and Survival:

• Pathogen survives on infected plant debris in soil
• Seedborne - primary infection
• Soil borne conidia from season to season

Management:

• Crop rotation
• Disposal of plant debris
• Seed treatment with Trichoderma viride @ 4 g/kg of seeds and soil application of T. viride @ 2.5 kg/ha with FYM @ 500 kg/ha
• Treat the seeds with carboxin 37.5% + thiram 37.5% DS @ 3 g/kg of seeds or carbendazim @ 2 g/kg of seeds