Argentine Ant Control on Citrus in California with Granular Formulations of Certain Chlorinated Hydrocarbons1

Abstract

Bentonite or attapulgus clay granules were found to be the most suitable substrates for general use with available types of dispersal equipment. The low volatile attapulgus clay particles were more desirable than attapulgus clay granules which tended to disintegrate in the presence of water and more quickly release the toxicant. The 30/60-mesh granules were preferred to larger granules. Granular formulations were found to be slightly more effective than spray formulations when equivalent amounts of toxicant per acre were applied. The practical dosage rate for granular treatments was found to be 50–100 lb/acre, depending upon toxicant used and the method of distribution. Uniformly dispersed over the surface of the ground these materials were effective for periods exceeding 10 months in greatly reducing or actually eliminating ant colonies established in citrus groves. Dispersal by aircraft was found to be the most effective method tested for applying granules. Residues occurring on and in the peel of fruit treated with air dispersions of chlordane and dieldrin granules were determined to be below established tolerances, and considerably lower than reported residues resulting from the use of these materials as aqueous sprays.