Granular Pesticide Formulations

Abstract

A granular pesticide formulation is one of the many options a formulator has to deliver the pesticide to the target. Granular formulations were first used for mosquito larviciding in swampy areas where foliage interfered with conventional pesticide formulations reaching the water. Today granular formulation use is widespread and most pesticides are formulated as a granule in addition to other formulations. Granules find use still for mosquito larviciding in addition to subsoil applications, soil surface applications, baits, and even some foliar applications (e.g. corn borer control). Granular carriers can be broadly separated into two categories, mineral and organic. Mineral carriers include sand, limestone, gypsum, kaolin, montmorillonite, attapulgite, diatomite, etc. Organic granular carriers include corn cobs, pecan shells, peanut hulls, recycled paper fiber, etc. In its simplest form, a granular formulation consists of the inert granule and the pesticide. If the pesticide is a liquid, it can simply be sprayed on the granule and distributed in the field. Often though, formulation aids such as solvents, stickers, deactivators and dedusting agents are included in the formulations. Each ingredient performs a specific function. Production methods usually involve spraying the pesticide onto the granules for even distribution while the granules are agitated. ASTM testing procedures for agricultural granules include sieve specifications, sampling procedures, bulk density, particle size distribution, resistance to attrition, particle count and liquid holding capacity. This article is a general introduction to granular formulations and provides specific information on carriers, formulation contents, use patterns, production methods and test procedures.