Studies on the grain yield loss of Isabgol (Plantago ovata) caused byAlternarialeaf blight

Abstract

To estimate the losses caused by leaf blight of Isabgol at varied disease intensity levels, field experiment was conducted for two consecutive years i.e., 2008 and 2009 of Rabi season. Different disease of leaf blight were generated through varied inoculum densities on two cultivars, Udaipur local and RI-89, using respective virulent isolates. It was found that the disease severity increased with increased inoculums levels, and a significant reduction in grain yields at all the severity levels was observed as compared to the uninoculated protected (Dithane M-45) control in each cultivar. The disease was more in 2009 than in 2008, yet the trend in reduction in grain yield was similar. In these two years of testing the percent disease index (PDI) ranged from 22.36 to 78.12 resulting into 11.19 to 34.73 per cent reduction in grain yield over uninoculated protected (Dithane M-45) control in Udaipur local cultivar. In RI-89, 17.34 to 71.88 per cent disease index (PDI) resulted into 9.45–30.55 per cent loss in grain yield over uninoculated protected (Dithane M-45) control.