Evaluation of New Insecticides and Fungicides for Compatibility and Management of Defoliators and Late Leaf Spot in Groundnut
Laboratory and field studies were conducted to evaluate the compatibility and bio-efficacy of newly released insecticides and fungicides alone and in combination against defoliator pests, Aproaerema modicella (Deventer); Spodoptera litura (Fabricius) and late leaf spot in groundnut during Rabi 2012-13. Slight phytotoxic symptoms (chlorosis) were seen in combination treatments of Thiodicarb 75 WP + Hexaconazole 5 EC and Chlorfenapyr 10 SC + Hexaconazole 5 EC with phytotoxicity score of 1 (0 to 10%) only at recommended dose. spinosad 45 SC + mancozeb 75 WP, spinosad 45 SC + hexaconazole 5 EC, flubendiamide 20 WG + hexaconazole 5 EC and chlorfenapyr 10 SC + hexaconazole 5 EC combinations at recommended dose were found to be superior to the rest of tested combinations with a mean per cent A. modicella larval population reduction of 87.5 and comparable to that of insecticides alone. The mean per cent defoliation by S. litura in insecticide alone treated plots ranged from 8.4 to 14.1% whereas it was 7.7 to 17.6 % in insecticide and fungicide combination treated plots and did not reduce the efficacy of the insecticides when mixed with fungicides. The fungicide and insecticide combinations registered the same efficacy with respect to late leaf spot disease (31-40% disease severity) compared to fungicides alone. The dry pod yields are also highest in insecticide and fungicide combinations (1806 to 2590 Kg/ha) compared to insecticides (910 to 1155 Kg/ha) or fungicides (1259 to 1368 Kg/ha) alone and untreated control (764 Kg/ha).