Variation in occurrence and morphology of Alternaria brassicae (Berk.) Sacc. causing blight in rapeseed and mustard

The results revealed a considerable variation in the occurrence, incidence and intensity of Alternaria blight in all locations which coincided with later stage of crop growth. Maximum occurrence was noted at University farm (80%) followed by Asadpur (60%) and maximum incidence was also noted at University farm (93.3%) followed by Panjipur (86.7%) and Chherat (86.7%). However, disease severity was recorded to its maximum in Panjipur (73.3%) followed by University farm (62.5%), Batoti (56%) and Chherat (36.8%). All eight isolates of A. brassicae infecting rapeseed-mustard and collected from different localities of Aligarh were also found to be pathogenically diverse. The average conidial length varied appreciably from 112.0 to 185.6. The maximum conidial length, breadth and number of septation was recorded in isolate Atrauli, however, other isolates namely, Panjipur and Chherat had a few similarity, yet they differed considerably with remaining isolates.