The biological activity of a pesticide, be it chemical or biological in nature, is determined by its active ingredient (AI - also called the active substance). Pesticide products very rarely consist of the pure active ingredient. The AI is usually formulated with other materials (adjuvents and co-formulants) and this is the product as sold, but it may be further diluted in use. Formulations improve the properties of a chemical for handling, storage, application and may substantially influence effectiveness and safety.[1]
Formulation terminology follows a 2-letter convention: (e.g. GR: granules) listed by CropLife International (formerly GIFAP then GCPF) in the Catalogue of Pesticide Formulation Types (Monograph 2); see: download page. Some manufacturers do not follow these industry standards, which can cause confusion for users.