SCREENING OF NEXT GENERATION FUNGICIDES AGAINST Alternaria brassicicola CAUSING ALTERNARIA BLIGHT OF MUSTARD

Alternaria leaf blight/black leaf spot caused by Alternaria brassicicola is an important disease of mustard. Bioassay of twelve chemical fungicide(s) was verified against Alternaria brassicicola in vitro following poison food technique at the Plant-Microbe Interaction Lab, Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh. Total inhibition (100%) of mycelial growth of A. brassicicola was obtained by Hexaconazol (Contaf 5EC), Iprodion (Rovral 50 WP) and Carbendazim (Autostin 50WP) containing fungicides at the lowest (0.0125%) concentration. Other fungicides were either partially effective or ineffective. Two fungicides viz. Contaf 5EC and Rovral 50 WP were selected based on their in vitro performance sprayed in the field onto foliage of mustard plants in four different concentrations (0.0125%, 0.025%, 0.05% and 0.1%) to evaluate the Alternaria leaf blight incidence and severity and some yield contributing parameters in treated and control plots. Among the used fungicides, Contaf 5EC @ 0.1% concentration showed the best performance in reducing disease incidence and severity as well as increasing the yield parameters such as number of pod per plant (61), pod length (4.9 cm), number of seed per siliqua (26.01) and thousand seed weight (3.81g) followed by Rovral 50 WP @ 0.1% in single and double sprayed plots compared to control and other fungicidal treatments.