Mode of Perpetuation and Effect of Environmental Factors on Target Spot of Soybean Caused by Corynespora cassiicola

摘要

The target spot of soybean pathogen (Corynespora cassiicola) over-seasons as mycelium in infected debris and seeds. The infected plant debris when incorporated in test plots developed disease much earlier and served as primary source of inoculum for infection. Blotter and agar plate tests confirmed the role of seed in the perpetuation and initiation of disease. Among environmental factors studied, a temperature range of 25-30C was found optimum for initiation and development of disease. RH at more than 80% was required for a successful infection and disease development. Disease severity was high at 100% RH and 25C. Twelve hours of alternate light and dark periods enhanced the disease development while exposure to complete light and dark resulted inreduced the disease.