Estimation of yield losses in soybean ( Glycine max (L.) Merrill) due to myrothecium leaf-spot disease in relation to crop age at the time of inoculation in India

Soybean crop inoculated with Myrothecium roridum at different days after sowing exhibited varying degrees of disease severity (44.4 to 83.3%) and yield losses (7.6 to 20.4%). Crops inoculated at 25 days after sowing had a maximum disease index (DI) of 94.4% and losses of 5.24 q/ha, which were significantly greater in comparison to those recorded in crops inoculated at 30, 35, 40 and 45 days after sowing. The yield losses were directly correlated with the disease index and every 1% increase in DI may result in further losses of 6.8 kg/ha. Delay in inoculation after the 25 day stage had a negative correlation with yield losses and a further delay of each day is likely to reduce the losses by 0.18 q/ha. Yield-contributory parameters of soybean also exhibited varying levels of losses due to the attack of myrothecium leafspot disease.

Keywords:

• Yield Losses
• Soybean
• Myrothecium Roridum