Estimation of yield loss due to powdery mildew in okra.

摘要

Powdery mildew caused by Erysiphe cichoracearum is an economically important disease of okra or bhendi (Abelmoschus esculentus). A field experiment was conducted to estimate the yield losses due powdery mildew by creating different disease gradients in an okra crop. A susceptible variety Arka Anamika was grown in the field and the crop was sprayed with a fungicide Penconazole (1%) at different growth stages after the natural appearance of powdery mildew symptoms to create varying disease severity levels. A total of seven treatments (6 sprays and a control) were planned in a RBD in four replications. The results revealed comparatively lower disease index (5.89%-7.98%) and increased yield (64.59 to 78.30 q ha-1) in plots receiving three to six sprays of penconazole. Disease was reduced to an extent of 81.48, 84.15, 84.85 and 86.34% when sprayed three, four, five and six times, respectively. Maximum yields were obtained from the plots receiving three sprays of penconazole compared to other treatments and untreated control (43.09 q ha-1). A crop yield loss model was developed as Y=74.26-0.79 PDI with R2=0.761.