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Agricultural spray adjuvants are used to enhance the effectiveness of pesticides. [1] [2] [3] They are used together with the pesticide itself (i.e. the active ingredient) to produce the mixture (pesticide formulation) which is then applied. The adjuvants do not control or kill pests, but they improve such properties as spreading, penetration, droplet size or other characteristics. Over twenty different types of adjuvants are on the market, including surfactants, oils, compatibility agents, buffering and conditioning agents, defoaming agents, deposition agents, drift control agents, and thickeners. [3]
Adjuvents may be part of an already formulated pesticide as purchased (in-can adjuvants), or may be added separately when the spray solution is being prepared (tank mix adjuvant). When delivered in-can, adjuvants may be quite effective. However, because of the limited space or limited compatibility in a pesticide formulation, not all necessary adjuvants may be included in-can. Thus, the addition of tank mix adjuvants may be necessary to optimize performance of the pesticide.
Agricultural spray adjuvants do not reduce the amount of pesticide needed below the recommended use rate on a pesticide label. In fact, it is illegal to use a pesticide in the US outside of the instructions on the label, although FIFRA, the US law governing pesticide use, does allow for the use of pesticides at rates below the label, as long as the label does not specifically deny such use. Agricultural spray adjuvants are used to enhance the performance of the legal amount of a pesticide that may be used. These adjuvants give more consistent performance and may make up for under-performance under certain conditions.
In the United States, agricultural tank adjuvants are essentially unregulated except in a few isolated cases. The states of Washington and California require that adjuvants be registered before they can be sold. Other states may or may not regulate adjuvants at some level. There is no federal regulation of tank mix adjuvants.
However, the industry itself has several efforts underway in order to self regulate the products. The ASTM International (ASTM) E35.22 committee is the committee that defines agricultural tank mix claims for the industry. The standard E1519 defines the various claims that an adjuvant may make and reference the methods by which the claim may be proven. The methods are tests, which when applied to a given sample, prove that the material meets the claimed standard.
Supporting the activities of ASTM is the Council of Producers & Distributors of Agrotechnology (CPDA), an organization of inert (or other) ingredient and adjuvant manufacturers. CPDA offers participating companies the ability to self-certify their spray adjuvant products in the USA by creating certain minimum standards that must be met in order to receive the CPDA stamp of certification.
In Canada, adjuvants are regulated by the Pest Management Regulatory Agency (PMRA) section of Health Canada. Each adjuvant must be tested and be proven to be safe and effective with every active ingredient with which it will be used. This much more stringent requirement prevents both the widespread use and questionable content present in the United States.
In the UK, the Chemical Regulations Directorate (CRD), part of the Health and Safety Executive, oversees the use of adjuvants. CRD defines an adjuvant as a substance other than water which is not in itself a pesticide but which enhances or is intended to enhance the effectiveness of the pesticide with which it is used. Adjuvants for use with agricultural pesticides have been categorised as extenders, wetting agents, sticking agents and fogging agents.