As a matter of convenience, adjuvants can be grouped into several distinct categories. The following is a list of these categories.
A. Wetting/spreading agents (surfactants): Sometimes referred to as wetting agents or spreaders. Generally used for the purpose of improving coverage and penetration of agrichemicals.
B. Penetrating surfactants:
C. Organosilicone super wetters: These products dramatically reduce surface tension to allow thorough penetration and maximum wetting and spreading properties on nearly all plant surfaces.
D. Stickers: This category name was chosen to designate an adjuvant that primarily imparts the property of adhesion of spray solutions. As a result of this property being added, spray droplets will have improved deposition and retention.
E. Water conditioning agents: When certain herbicide chemistries, such as glyphosate, sulfonylurea, imidazilinone, and phenoxy are added to water, the negative charges in the herbicide molecules attract the positive ions (cations) in water (i.e. calcium, potassium, magnesium). The herbicide and these cations form a strong complex, which can prevent or hinder uptake of the herbicide into the plant, effectively reducing herbicide performance. Water conditioners sequester and chelate cations freeing the herbicide molecules to perform more effectively.
F. Nitrogen containing adjuvants: These products have historically been used with herbicides, and are sometimes regarded as anti-antagonism agents to be used in conjunction with surfactant adjuvants. Success with this type of product seems to be specific with certain herbicide chemistries, weed species and carrier volumes. The exact mode of action of this group is still being debated; however, it is generally felt that their use promotes uptake and/or translocation of the herbicide. There may be some activity related to reducing impact of certain aspects of minerals in the spray water.
G. Basic N blend: Basic blends provide a higher pH combination of fertilizer source and non-ionic surfactant, facilitating solubility of sulfonylurea and stabilizing the mixture for micro rates on sugar beets.
H. Droplet size management (drift reduction):
This category of adjuvant product is usually a viscoelastic (having
both viscous and elastic properties) polymer that is added to spray
solutions to reduce the production of fine droplets. It is known that
very small droplets (usually under 150 microns in diameter) are most
susceptible to non-application as well as off-target application. Drift
reduction polymers tend to increase the size (and weight) of droplets
produced by a spray nozzle and as a consequence, reduce
opportunity for losses and off-target application.