While all adjuvants serve to improve crop protection performance, they do so in one of two specific ways. One group called special purpose/utility adjuvants, serve to make tank mix ingredients work better together. The other group, called activator adjuvants, get their name from what they do: activate crop protection products. To learn more about activator adjuvants, read our blog “Get to Know Adjuvants: Activators”.

What are Special Purpose/Utility Adjuvants?

Special purpose/utility adjuvants work by altering the physical characteristics of the spray solution for maximum performance. They correct issues in the tank mix that could negatively affect spray applications, so every droplet leaving the sprayer is providing effective weed control. This group includes drift control agents, deposition aids, compatibility agents, water conditioners, and other special purpose/utility adjuvants.

Types of Special Purpose/Utility Adjuvants

Drift Control Agents (Drift Reduction Agents)

Drift is the unintentional, off-target application of crop protection products. Factors such as severe temperatures, high wind speeds, nozzles used, and small droplet size can increase drift and decrease the performance of crop protection products. Drift control agents are especially important to use near sensitive sites to prevent damage to surrounding crops and when facing less than ideal weather conditions.

Drift control agents can help to improve the precise placement of a pesticide spray by increasing the spray droplet size. Larger droplets remain on leaves longer and spread better than smaller droplets, helping with improved foliar intake. Consult the product label for information about optimal droplet size and calibration of nozzles. Drift control agents are the most common adjuvant used with crop protection products, and some new dicamba herbicides even require an approved drift reduction agent (DRA) in the tank mix.

As shown in the image below, drift control agents create the ideal spray droplet size for penetration. Droplets that are too small will drift away (left). Droplets that are too large will bounce off leaves (middle). Ideal droplet size aids with placement and penetration (right).

Deposition Aids (Stickers)

Deposition aids, or stickers, are often used to increase the ability of water-soluble pesticide particles to stick to a plant’s surface, reducing evaporation for a waterproof coating. This stickiness helps to keep the particles in place through rain and irrigation while preventing degradation from UV rays. Deposition aids are one of the most used adjuvants on the market, and many include a surfactant for better coverage and stickiness on a target surface. As shown in the image below, deposition aids help to keep particles in place for better penetration.

Compatibility Agents

When aid is needed to stabilize and disperse formulations, compatibility agents are used. They ensure tank mix ingredients work together physically and chemically. By reducing clumps and uneven distribution in the tank, they prevent clogging of pumps and hoses, which can cause application problems and expensive cleanup and repairs.

Water Conditioners

Water is an essential and working part of any spray solution. The molecular, chemical and physical properties of water used in a tank mix can change the effectiveness of the solution. Before starting a tank mix, water should be tested to see if any properties need to be altered for maximum spray application effectiveness. Below are the different types of water conditioners used if hardness, acidity, or alkalinity is detected.

Conditioning Agents

Hard water can contain positively charged ions like potassium (K+), calcium (Ca+), magnesium (Mg+), and sodium (Na+). These ions can bind to and deactivate active ingredients, decreasing crop protection product performance. A water conditioner or water-softening agent will bind to molecules in hard water ions, ensuring the efficacy of the spray solution.

Acidifiers and Buffering Agents

Some crop protection products like herbicides perform best in slightly acidic water with a pH of 4.0-6.5. If water is alkaline, an acidifier adjuvant can lower the pH. Adding a buffering agent, or buffer can then stabilize the solution at an acceptable pH level for maximum performance.

Other Special Purpose/Utility Adjuvants

While 80 percent of adjuvants fall into five categories, surfactants or deposition aids (50%) and oils, foliar nutrients, and compatibility agents (30%), there are several smaller categories of adjuvants as shown in the figure below.

Now more than ever, it’s important for retailers to stay engaged with their CHS Agronomy representative to stay up to date on the latest adjuvant technology in order to select the best adjuvants for their operation and profitability. It’s also important for growers to talk with their agronomist about how adjuvants are vetted, selected, and used to enhance crop protection products applied to their operation.

CHS Agronomy develops and offers a full range of special purpose/utility and multifunctional adjuvants, from drift inhibitors and buffers to compatibility agents, deposition aids, and surfactants to enhance herbicide, fungicide, and insecticide technologies on the market.

For more information about adjuvants, download the CHS Agronomy white paper "Using Adjuvants to Improve Crop Protection Performance". For a listing of available adjuvants visit the CHS Agronomy website.