Bioefficacy and Persistence of Synthetic Pyrethroids in Cotton

Field trials conducted on the bioefficacy and persistence of two dosages of synthetic pyrethroids showed effectiveness of both the dosages in control of cotton bollworms in comparison to the recommended dose of conventional insecticide, carbaryl. No significant differences could be established between the two dosages except in flucythrinate. Minimum incidence of bollworms and maximum yield of seed cotton were recorded with flucythrinate applied at the rate of 50 g a.i./ha. The use of synthetic pyrethroids showed early opening of bolls and less stained seed cotton. The residues of synthetic pyrethroids were much lower than those of carbaryl and their level sharply declined in the second picking. Detected residues were below their prescribed limit in all the insectiadal treatments and considered safe even for cotton seed oil.