The leaf blight disease of mustard caused by Alternaria brassicae is among the most destructive diseases which cause high losses in mustard production. In present study the efficacy of fungicides as well as some botanicals was evaluated in vitro at three concentrations viz., 100, 150 and 200 ppm against mycelial growth of Alternaria brassicae. Among these fungicides it was observed that propiconazole 25% EC, propineb 70% WP and carbendazim 12% combined withmancozeb 63% WP was got hundred percent mycelial growth inhibition of Alternaria brassicae in-vitro at all three concentrations with comparison to control. The botanicals were also evaluated as crude extract in 20% concentration against A. brassicae under In-vitro conditions. Among these botanicals it was observed that A. sativum completely inhibited the growth of mycelium (0mm). Azadirachta indica and Eucalyptus amyladin also inhibit the growth of Alternaria blight significantly (11.33mm, 15.67mm respectively). The other plant extracts also showed blight growth inhibition significantly as compared to control which recorded maximum growth of mycelium (85.33mm) after seven days of inoculation