Late leaf spot: Cercospora personata (Mycosphaerella berkeleyii)

Symptoms:

• Infection starts around 55-57 days after sowing in Kharif and 42-46 days after sowing in Rabi
• Black circular spots on the lower surface of leaf
• Aggregation of lesions cause early ageing and leaflet shedding

Late leaf spot	Late leaf spot and rust

Pathogen:

• Mycelium: Intercellular
• Conidiophores: Long, 1-2 septate and arise in clusters
• Conidia: Cylindrical, short, hyaline, straight with 1-9 septa
• Pseudothecium: Bear cylindrical to ovate asci with 8 ascospores
• Ascospores: Hyaline and 2 celled

Conidia

Favourable Conditions:

• Prolonged high relative humidity for 3 days
• Low temperature (20ºC) with dew on leaf surface
• Heavy doses of nitrogen and phosphorus fertilizers
• Deficiency of magnesium in soil

Mode of Spread and Survival:

• Primary infection: Ascospores or conidia from infected plant debris or infected seeds
• Secondary spread: Airborne conidia
• Rain splash and wind also spreads conidia

Management:

• Intercropping pearl millet or sorghum with groundnut (1 : 3)
• Crop rotation with non-host crops preferably cereals
• Removal of volunteer groundnut plants
• Treat the seeds with carbendazim @ 2 g/kg
• Spray carbendazim @ 500 g/ha or mancozeb @ 1000 g/ha or chlorothalonil @ 1000 g/ha. If necessary, give the second spray after 15 days