Understanding Adjuvants and Surfactants in Ornamental Crop Production

By Andi Anderson

Pesticides are essential tools for protecting ornamental crops from insects, weeds, fungi, and other pests. However, their performance can often be enhanced with the use of adjuvants, especially surfactants.

While pesticides target and control harmful organisms, adjuvants are substances added to formulations or spray mixtures to improve how pesticides work. They do not directly control pests but enhance effectiveness, safety, and consistency.

According to the “Weed Control Methods Handbook,” adjuvants improve pesticide performance by enhancing mixing, altering spray behavior, or reducing unintended effects. They are especially useful under challenging environmental conditions or when tank-mixing different products.

Unlike pesticides, adjuvants are not federally regulated, though some states, like California, classify them as pesticides and require reporting.

Different types of adjuvants serve specific purposes:

• Defoamers minimize foam during mixing, improving handling.
• Compatibility agents prevent separation or clumping in tank mixtures.
• Drift control agents reduce off-target spray movement by enlarging droplet size.
• Buffers or pH modifiers help maintain an optimal pH (5.5–7) to prevent pesticide breakdown.
• Extenders and stickers keep pesticides active on surfaces longer and improve adherence.
• Wetting agents improve the dissolving of powders for consistent spray solutions.
• Spreaders create uniform spray coverage for greater effectiveness.
• Safeners reduce crop injury and protect applicators.
• Emulsifiers help water-based pesticides mix with oil-based carriers.
• Penetrants improve absorption of systemic pesticides into plant tissues.
• Thickeners reduce spray drift and evaporation, prolonging absorption time.

Before selecting an adjuvant, growers should carefully read pesticide labels, technical sheets, or consult manufacturers for recommendations. Many pesticide products already include adjuvants, and unnecessary additions can reduce effectiveness or harm plants. Only adjuvants specifically manufactured for agriculture or horticulture should be used.

For best results, growers should test spray mixtures on a small area before widespread application.

Proper selection and use of adjuvants and surfactants can lead to more effective pest management, reduced costs, and improved crop health in ornamental production.

Photo Credit: gettyimages-v_zaitsev