Symptom

Spots on leaf 

• The disease appears as minute black or brown points surrounded by a pale green ring.
• These spots are visible on both the surfaces of the leaf.
• As the spots enlarge, the centre turns pale brown and then greyish-white surrounded by a deep brown band which may be narrow and sharp or broad and diffused.
• The fructifications of the fungus appear as tiny black dots in the white centre.
• The diseased spots often occur in great numbers scattered over the leaf and are roundish when young but may become irregularly angular when mature.
• When the spots are close together, the intervening leaf tissue withers and large brown patches of dried leaf may result

Management

• Spraying with Mancozeb 0.25%
• Spraying twice with Mancozeb 2.5g/lit at 10-15 day interval reduces the disease incidence.
• Treat the seed with Thiram or Captan 4g/kg seed.