Alternaria leaf blight: Alternaria arachidis and A. tenuissima 

• Irregular lesions surrounded by yellowish halo on leaves
• Light to dark brown colour on tip of leaflets
• Blighted leaves curl inward and brittle
• Lesions coalesce giving ragged and blighted appearance

Alternaria leaf blight

Pathogen:

• Conidiophores grey
• Conidia obclavate, light olive with transverse and longitudinal septa in chains

Favourable Conditions:

• Relative humidity: > 85%
• Optimum temperature: 25-30⁰C

Mode of Spread and Survival:

• Primary spread: Infected volunteer plants
• Secondary spread: Airborne conidia

Management:

• Remove and destroy the infected plant debris
• Eradicate volunteer plants
• Treat seeds with carbendazim @ 2 g/kg
• Foliar application of mancozeb 72 WP (1000 g/ha) or copper oxychloride 50 WP (2000 g/ha) or carbendazim (500 g/ha)