Without proper wetting and spreading, spray droplets often run off or fail to adequately cover these surfaces. Too much surfactant, however, can cause excessive runoff or deposit loss, thus reducing pesticide efficacy. A surfactant with a negative charge is anionic, one with a positive charge is cationic, and one with no electrical charge is nonionic. Pesticidal activity in the presence of a nonionic surfactant can be quite different from activity in the presence of a cationic or anionic surfactant. Selecting the wrong surfactant can reduce the efficacy of a pesticide product and injure the target plant.
Anionic surfactants are most effective when used with contact pesticides.
Nonionic surfactants, often used with systemic pesticides, help pesticide sprays penetrate plant cuticles. Pesticide formulations often contain surfactants to improve the suspension of the pesticide s active ingredient. A sticker is an adjuvant that increases the adhesion of solid particles to target surfaces. These adjuvants can decrease the amount of pesticide that washes off during irrigation or rain. Many adjuvants are formulated as spreader-stickers to make a general purpose product that includes a wetting agent and an adhesive.