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By Dr Brian de Villiers
March 2026
The word “adjuvant,” means “to help.” These products are therefore used exclusively to help crop protection products (CPPs) reach their full potential. Adjuvants reduce the impact of adverse weather conditions and spray water, thereby stabilising the control of weeds, insects and diseases in a wider range of environments. Although these products
are intended to help CPPs, they can do exactly the opposite if used incorrectly. This is unfortunately a reality, and we often see the ugly side of adjuvants because of misconceptions and malpractices. Therefore, it is important to use these products correctly to ensure optimal efficacy, without causing any unwanted issues.
When adjuvants help
From the time when CPPs are included in the spray mixture until their function is completed on the leaf, they are exposed to detrimental conditions. These include poor water quality, low humidity, waxy and hairy leaves, and various others. Buffers are used
to decrease pH in order to limit alkaline hydrolysis, while salt adjuvants are used to address dissolved antagonistic cations. Deposition agents manipulate the droplet spectrum to get more product to the crop or weed. Surfactants and oil adjuvants increase coverage by reducing spray droplet bounce off the leaf. They also spread the droplet on the leaf to create a larger contact area and hydrate the waxy layers to help with the absorption process. When all these adjuvants are used responsibly, they increase efficacy and stabilize the activity of the CPP over various environments and water sources.
When adjuvants harm
Adjuvants are beneficial and will increase control, but if they are not used correctly, they can cause harm. Buffers and salt adjuvants that decrease the spray solution pH too much, can cause incompatibility, insolubility, and poor efficacy. Deposition agents with no other ingredients in the formulation are sometimes used incorrectly to replace other adjuvants like surfactants and oils. One must realize that when using some deposition
agents, surfactants and oils may still be necessary. By replacing one type of adjuvant with another, the chance for poor efficacy increases. One of the most common malpractices is that the recommended surfactant or oil is replaced with another product. Remember that different surfactants and oils differ in retention ability, spreading ability, and absorption ability. By replacing the registered adjuvant with another product, all these processes can be impaired and the chance for inefficacy and crop damage increases dramatically.
Villa’s stance
Please use adjuvants according to label recommendations, because although they help CPPs to reach their potential, they can also harm efficacy if used incorrectly. Contact your Villa agronomist for more information about adjuvants and water quality.