Many tree health professionals use adjuvants with their spray treatments to increase the results of their treatments or make them easier to apply. An adjuvant is an agent added to a solution to increase or aid in the effect of the treatment. Adjuvants can help with improved surface coverage, improved rainfastness, drift control, defoaming, and reducing product buildup in equipment.

Droplets will naturally bead up in larger groups, reducing the surface area contact with the leaf. Surfactants reduce the surface tension of droplets for superior coverage, penetration, and uptake of pesticide actives. Drift controlling adjuvants modify sprays to maximize droplets within the ideal size range - large enough to avoid drifting off target - small enough to avoid bouncing off the target. Without drift control, small droplets form and are harder to control. Anti-foaming adjuvants can help with herbicides and other pesticides known to cause excessive foaming and application equipment that continuously agitates spray solution.