Downey mildew disease:
Causal organism: Peronosclerospora sorgi
Symptoms:
· It Development of chlorotic streak on the leaves within 2 weeks of sowing.
· Plant exhibits a stunted and bushy appearance due to shortening of the internodes.
· Dowing growth also occurs on the breasts of green unopened flower.
· On leaves lower surface of leaf white downy growth in seen.
· Proliferation of auxiliary bunds on the stalk of tassel and cob (Gassy top).
· The lower mature leaves may also show considerable quantity of symptoms only if the plants are systemically infected.
Favourable condition:
· Temperature: 20-30 degree.
· Relative humidity: 90%
· Young plant is highly susceptible.
Disease cycle:
Perennation:
· Spores are oospores present in the soil, crop debris.
Primary infection:
· Spores in soil, dormant mycelium presents in infected maize seeds.
Secondary infection:
· Through airborne conidia, irrigation.
Management:
Cultural method
· Deep ploughing.
· crop rotation with pulses.
· Use resistant varieties: CO1, COH1, COH2.
· Rogue out infected plant.
Chemical method
· Seeds treated with metalaxyl at 6g/kg.
· Spray the crop with Metalaxyl + Mancozeb@1kg on 20th day after sowing.
