Introduction to major field crops (1+1)

Diseases

Downey Mildew: Appearance of vivid green and white stripes on leaves. Stunted growth and failure to produce head at advance stage is observed. Seed dressing with Metalaxyl (Ridomil 25) at 1.0 g/kg control infection. In field, spray of' Metalaxyl0.01 per cent 40 days after germination check spread of Downey mildew.

Grain Moulds: This disease is caused by many fungal species. Grains infected with Fusariummoniliforme have white or pinkish colour, while grains infested with Curvularialunata have black appearance. Discolouration of grain, reduction in grain weight leading to 75-100 per cent damage. The harvested grains are also toxic to animals. Seed treatment with Captan 4 g/kg seeds is a preventive way. In field, three sprays of Aureofungin 200 ppm + Captan 0.3 per cent from 50 per cent flowering at 10 days interval is costlier but very effective. Spraying three timesDithaneM-45 and Bavistin 0.2 per cent from flowering at 10 days interval control grain mould.

Rust:Rust pustules invade the lower leaves. In susceptible varieties entire leaf tissues are destroyed by pustules. Use of clean seed, crop rotation and use of resistant varieties are preventive ways against this disease. Effective control in field could be achieved by four sprays of Dithane M-45 at 0.2 per cent at 10 days interval from 30 days after germination.




Fig: Rust.