The study demonstrate morphological and physiological variations in isolates of Alternaria brassicae and to evaluate the efficacy of fungicide (in vitro) on radial growth of the fungus and foliar sprays (field) against the disease severity on rapeseed-mustard. Morphological variations of A. brassicae obtained from various places were differed in their conidial size and septation. Physiological response of A. brassicae at varying temperatures, the fungus showed its maximum growth at 25°C followed 20°C and on different culture medium, maximum radial growth is on PDA. However, the fungus...