STUDIES ON COMPATIBILITY OF AVERMECTINS AND CHITIN SYNTHESIS INHIBITORS WITH COMMON FUNGICIDES

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Date
2010
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD
Abstract
Studies on compatibility of avermectins and chitin synthesis inhibitors with common fungicides were carried out with Spodoptera litura Fabricius and Aspergillus flavus as test organisms in the Department of Entomology, College of Agriculture, Rajendranagar, Hyderabad during 2009-2010. The LC50 of the insecticides viz., abamectin, emamectin benzoate, novaluron and lufenuron against S.litura was determined as 210.23, 102.12, 350.45 and 453.78 ppm, respectively, whereas the fungicides viz., mancozeb, chlorthalonil, and carbendazim recorded LC50 values of 97.0, 1.16 and 40.94 ppm respectively. The test insecticides were non toxic to A.flavus at LC50, field recommended and other concentrations, whereas fungicides were also non toxic to S.litura. Of all the insecticide – fungicide combinations studied on the larval mortality of S.litura, the combination of emamectin benzoate with carbendazim at their LC50 values recorded maximum antagonism. Equivalism was observed in the combinations, abamectin with mancozeb, emamectin benzoate with chlorothalonil, lufenuron with mancozeb and lufenuron with chlorothalonil at their respective LC50 values. All other combinations showed varied degrees of synergism and antagonism. Abamectin LC50 in combination with mancozeb and carbendazim at field recommended and other concentrations showed synergism. Whereas, in combination with chlorothalonil, it showed antagonism at field recommended dosage and equivalent effect at concentration below the field recommended dosage. Emamectin benzoate LC50 in combination with mancozeb at three different concentrations showed antagonism. Whereas, with carbendazim resulted no change in the insecticidal activity when combined with emamectin benzoate showing equivalent effect at lower concentration. Novaluron LC50 in combination with fungicides carbendazim antagonism was observed and chlorothalonil at three test concentrations showed equivalent effect without any change in insecticidal activity. Whereas, the mancozeb at higher concentration showed synergism, but no effect at lower concentration. Chlorothalonil at all the three test concentrations when combined with lufenuron LC50 resulted in enhanced insecticidal activity indicating synergism. Similar effect was observed with fungicides carbendazim only at their higher concentrations. All other combinations resulted in equivalent effect showing no change in the insecticidal activity of lufenuron.(LC50). Of all the fungicide – insecticide combinations studied on the inhibition of spore germination of A.flavus, carbendazim in combination with abamectin at their respective LC50 values resulted in maximum antagonism. However, rest of the combinations showed varied degrees of synergism and antagonism. Mancozeb (LC50), showed antagonism in combination with emamectin benzoate at all concentrations while with abamectin, novaluron and lufenuron synergism was observed at field recommended and higher concentrations. Antagonism was observed at lower concentrations with the three insecticides. Carbendazim (LC50) showed antagonism in combination with abamectin at all test concentrations and with lufenuron at concentration higher than field recommendation. While antagonism was observed with emamectin benzoate and novaluron at all test test concentrations and with emamectin benzoate only at lower concentration. Chlorothalonil LC50 showed synergism in combination with abamectin, while antagonism was recorded with emamectin benzoate and novaluron at all test concentrations. However, in combination with lufenuron, antagonism was recorded at lower concentration and synergism at field recommended and higher concentrations. The wettability and emulsion stability of the insecticides remain unchanged when mixed with the fungicides. The wettability of the WP formulations of fungicides was not affected when mixed with any of the insecticides. All the fungicidal formulations remain unchanged when mixed with insecticides abamectin, emamectin benzoate, novaluron and lufenuron. WP formulation of fungicide viz., mancozeb, carbendazim and chlorothalonil altered the emulsion stability of abamectin on mixing. All the combinations of test insecticides and fungicides showed no phytotoxic symptoms on one and half month old groundnut plants at recommended concentrations.
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STUDIES,COMPATIBILITY, AVERMECTINS, CHITIN, SYNTHESIS, INHIBITORS,COMMON, FUNGICIDES
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