Effect of plant age on the development of early blight [Alternaria solani (Ellis and Martin) Jones and Grout] on tomato and correlation of weather parameters with disease severity under field condition.

摘要

Effect of plant age on the development of early blight [Alternaria solani (Ellis and Martin) Jones and Grout] on tomato was evaluated in relation to host susceptibility under controlled and uncontrolled environmental conditions. The per cent disease index (PDI) of early blight increased with increased age of tomato plant and an age of 50 days and above was found to be highly susceptible to the disease. The PDI of the infected plants with optimum condition in growth chamber (91.08% at 80 days old) was significantly higher than the infected plants in net-house condition (42.33% at 80 days old) at the same stage of plant. The weather studies revealed that PDI was progressing at linear rate throughout the plant growth and it was negatively correlated with minimum temperature (r=-0.8270) and relative humidity (r=-0.4106); while, rainfall (r=0.0227) had no significant correlation with PDI.