Controlled Release Temephos: Laboratory and Field Evaluations

Abstract

The development of controlled-release pesticides based upon the monolithic dispersion of a chemical agent in a polymer has been described in detail elsewhere.¹ Temephos, 0,0,0’,0’-tetramethyl-0,0-thiodi-p-phenylene phosphorothioate (C.A. Registry #3383–96–8), was incorporated in elastomeric matrices and a diffusion-dissolution type release mechanism was established.² Although a continuous release of the agent occurred for over three years, commercialization was not undertaken. Later it was discovered that long-term toxicant release from a plastic matrix could be achieved through a leaching process keyed to the use of a water-soluble additive whose emission led to the development of the necessary porosity in the matrix.³ The processing costs for such materials are relatively inexpensive, and consequently a number of controlled-release temephos materials are now commercially available. Unlike conventional formulations which are limited to solutions, emulsions, granules, and wettable powders, controlled-release plastic dispensers can be manufactured in any geometry conducive to the particular environment to be treated.