Excerpt from the article “Activator Spray Adjuvant Selection: Crop Spraying” by Franz Niederholzer, UC Farm Advisor, Sutter/Yuba Counties, and Rhonda Smith, UC Farm Advisor, Sonoma Co. on the San Joaquin Valley Trees and Vines website.

Agricultural spray adjuvants are materials added to the spray tank when loading the sprayer. They include products classified as activator adjuvants and marketed as wetters/spreaders, stickers, humectants, and/or penetrators. Activator adjuvants are marketed to improve the performance of pesticides and foliar fertilizers. Activator adjuvants can have a place in tree (and vine) crop sprays, but matching the material to the job can be tricky. A bad match can lead to minor or major losses to the grower. Minor losses can result from excess spreading and pesticide runoff from the target plant. Phytotoxicity can cause major damage. This article describes ingredients and functions of activator adjuvants commonly sprayed on tree and vine crops. Suggestions regarding activator adjuvant selection are offered. Growers must make their own activator adjuvant use decisions based on experience, particular needs, and risk tolerance.

Read the full article on San Joaquin Valley trees and Vines.

Agricultural spray adjuvants are materials added to the spray tank when loading the sprayer. Photo by Jack Kelly Clark.