Efficacy of Fungicides and Plant Extracts against Alternaria Blight of Clusterbean

摘要

Alternaria blight caused by Alternaria cucumerina var. cyamopsidis is a serious foliar disease of clusterbean in northern India. Disease control efficacy of nine fungicides viz, mancozeb (Dithane M-45 75 WP 0.2%), zineb (Dithane Z-78 75 WP 0.2%), chlorothalonil (Kavach 75 WP 0.2%), copper oxychloride (Blue copper 50 WP 0.2%), carbendazim 2% + mancozeb 63% (Companian 65 WP 0.2%), propineb (Antracol 70 WP 0.2%), propiconazole (Tilt 25 EC 0.1%), hexaconazole (Controll 5 EC 0.1%) and difenconazole (Score 25 EC 0.1%) were evaluated against Alternaria blight of clusterbean variety RGC-936 during kharif seasons of 2006 and 2007. These fungicides were sprayed twice at 45 and 60 days after sowing (DAS). In another experiment, plant extracts viz, Azadirachta indica (neem leaf or seed kernel 10%), Nimbecidine (azadirachtin 0.03%), and leaf extracts (10%) of Withania somnifera, Aloe barbadensis, Calotropis gigantia, Ocimum sanctum, Nerium odorum and Vinca rosea were also tested. The disease intensity was significantly reduced by fungicidal sprays. The disease severity was low in treatments with difenconazole and chlorothalonil (<20%) compared to that in control (74%). Nimbecidine (azadirachtin) spray treatment provided a good level of disease control (59%). Treatments with aqueous leaf extract of Calotropis, and Azadirachta as well as its seed kernel extract were also effective in controlling blight. The highest and significantly enhanced grain yield was with difenconazole and the next best was with chlorothalonil. Azadirachtin, Calotropis leaf or Azadirachta seed kernel and leaf extracts also enhanced grain yields.