YIELD LOSS ASSESSMENT OF WHEAT DUE TO LEAF BLIGHT DISEASE CAUSED BY Bipolaris sorokiniana

Abstract

The experiment was conducted in the farm of Sher-e-Bangla Agricultural University and central laboratory of the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka-1207 during the Rabi season from November 2014 to June 2015. The experiment was laid out in a RCBD (one factor) with three replications. Multiple treatment experiment with 11 treatments, viz. To (control); Tl (1 spray with Tilt 250 EC @ 0.1%); T2 (2 sprays with Tilt 250 EC @ 0.1%); T3 (3 sprays with Tilt 250 EC @ 0.1%); T4 (4 sprays with Tilt 250 EC @ 0.1%); r,(5 sprays with Tilt 250 EC @ 0.1%); T6 (6 sprays with Tilt 250 EC @ 0.1%); T7 (7 sprays with Tilt 250 EC @ 0.1%); Ts (8 sprays with Tilt 250 EC @ 0.1%); T9 (9 sprays with Tilt 250 EC @ 0.1%); TIO (10 sprays with Tilt 250 EC @ 0.1%) were applied in the experiment to make the variation in the disease severity and respective yield of treated plot. Different treatment comprising different number of spraying had remarkable influence the disease severity of leaf blight, yield and yield contributing characters of wheat. The lowest (0.0%) percent disease index (PDI) and the highest yield (5.35t1ha) was recorded in case of treatment Tro where 10 spraying were done with Tilt-250 EC @ 0.1%. The highest PDI and the lowest yield were counted in case of treatment To (control). The disease severity and yield was varied significantly on the basis of number of spraying. Using the varied disease severity (PDI) and the corresponding yield the regression equation for yield loss assessment was constructed as Y = 2.58+ 0.40Xi where 0.4 % loss of yield would be incurred for increasing each percent of disease severity (PDI).