Symptom

Dead seedling

• The disease first makes its appearance on both the surfaces of the cotyledonary leaves in the form of roundish patch of dull green colour which soon spreads to the point of attachment causing the leaf to rot and hang down.

Spot on older leaf    

• The infection further spreads to the stem with the result that the seedling is killed either due to the destruction of growing point or by the collapse of stem.
• The true leaves of seedlings and the very young leaves of older plants may also be affected; but ordinarily not much injury is caused.
• The leaf spots turn yellow and then brown and concentric zones of lighter and darker brown colour are formed.
• The disease spots coalesce at a later stage and cover almost the entire leaf.
• The affected leaves shed prematurely. Under moist conditions, a very fine whitish haze is found on the under-surface of the leaf spots.
• In case of mature plants also the disease may spread from young leaves to the stem through the petiole.

Management

• Ill drained, damp and low lying localities should be avoided for sowing castor.
• Seed dressing with 4g Trichoderma viride formulation on 3g Metalaxyl per kg seed can reduce disease incidence.
• Soil drenching with Copper oxychloride @3g /lit or Metalaxyl 2g/lit