Plant Disease Research

The yield losses were assessed on four varieties of mustard viz., RH-30, RH-8113, RH-9304 and RH-9801 by maintaining plots free from disease by spraying Sulfex (0.2%) at 10 days interval The disease intensity recorded at the end of crop season revealed that average losses were between 19 and 293 per cent. It caused losses to the tune of 29.5 per cent in variety RH-9304, 26.4 per cent in RH-9801, 23.0 per cent in RH-8113 and the minimum 19.0 per cent in variety RH-30 when disease intensity in unsprayed plots ranged between 62 and 68 per cent The data also revealed that there was negative correlation between disease intensity and yield components. The average yield loss (24.5%) irrespective of the varieties was observed at maximum disease intensity (643%). Out of the 54 lines/germplasm/varieties screened under natural field conditions, four varieties viz. HC-1, HC-2, HC-9605, HC-9603 belonging to B. carinata and two genotypes B. alba and Sinapis alba did not contract powdery mildew. Five varieties viz., GSL-1, Midas, MNS-9605, YSPb-24 and TH-68 were considered as resistant Five varieties viz., Domo-4, BSH-1, TMH-50, TMH-52 and T-27 were moderately resistant.