When deciding which adjuvants to use with active ingredients in a tank mix, it’s important to consider a few factors of the adjuvants. Before our products hit the market, extensive lab testing is conducted to understand how these adjuvants will behave and perform in real-world scenarios. These tests give valuable information to help users decide which adjuvants to include. One crucial test is measuring surface tension, which assesses how well a liquid can spread over a target, like a weed leaf or unwanted insect.
Since molecules are cohesive, a liquid wants to stay together, and the surface of a liquid allows it to resist an external force that prevents spreading over the target or breaking up into smaller droplets. A surface tension test measures that force. The surface tension measurement gives an idea of a formulation’s surfactant qualities. The lower the surface tension number, the better the formulation will spread.
At Exacto, Inc., we use a tensiometer to measure the surface tension. The process consists of the following steps:
To see the measurement in action, watch the video below.
Think about pulling your foot free from mud. It grabs you and doesn’t want to let go. The same thing happens with liquid on this plate, it just doesn’t hold on nearly as hard.
The same surface tension aids in the formation of emulsions, where substances like oil form small drops in water rather than mixing evenly. Lower surface tension helps create stable oil-water emulsions that last longer. In many tank mixtures, water is blended with oils and oil-based materials, making surface tension crucial to optimize a tank mix beyond just spreading on the intended target.
When a substance with a high surface tension is sprayed or dropped onto another surface, it beads up, causing it to roll off or sit on top of the surface without spreading out. This is often seen with pesticide tank mixes in both agriculture and turf. Pesticide spray droplets with high surface tension result in lower efficacy as more droplets roll off the target.
Adding a surfactant to a liquid can lower surface tension, encouraging wetting on grass and crop leaves, soil, and other surfaces. Better wetting means the droplet spreads out on the leaf, decreasing the likelihood that it will roll off target. Lower surface tension can also result in increased droplet size of spray fans.
Knowing the surface tension of a adjuvant is important because it tells its spreading capabilities. If the surface tension is under 50 newton meters per meter (Nm/m), the adjuvant has surfactant properties. Good surfactants at low concentrations (0.25%) can lower the surface tension of water to anywhere from 25 to 35 Nm/m, less than half the surface tension of plain water.
The surface tension test serves as a valuable tool for assessing adjuvant properties. When combined with other pertinent tests, such as contact angle and the Draves Test, it yields tangible data about the essential traits of a solution. Although these tests may not always show a direct one-to-one relationship with a solution’s ability to wet a surface, they do offer insights into the formulation’s characteristics. The process of wetting solid surfaces is intricate and influenced by a variety of factors, and measuring surface tension is a practical means of gauging the likelihood that an adjuvant will effectively cover a target
Understanding formulations starts in the lab. Knowing the specifications of a product can help users understand how they use may act and perform in the real-world. Exacto Chemist, Chris Walter, explains Contact Angle to help applicators better understand the chemistry behind surfactants, sticker spreaders, and wetting agents in this edition of the Research to Real-World series.
With tightening EPA regulations and increased label restrictions on dicamba, Corteva’s Enlist One® and Enlist Duo® are seeing increased adoption. As more growers make the change, choosing the right adjuvants to use with Enlist One and Enlist Duo is key to ensuring optimum weed control.
Explore UW-Madison’s turf research studies from the Wisconsin Turfgrass Association Field Day. Dr. Soldat’s Soil Science Program showcased an athletic field management study comparing conventional & organic approaches. Dr. Koch’s Plant Pathology Program highlighted a leaf mulching study.
With a dry spring hanging over the corn belt, concerns of returned crop stress remain going into the second half of the season. Regional drought monitor maps give reason for this concern as drought lingers in across much of the central US.
Turf needs water to survive. If not managed effectively, soil moisture can cause consistent problems such as water-repellancy that create dry patches, inconsistent turf appearance, and in severe cases, complete loss of turf. Turf wetting agents help move water into the soil, improve uniformity, and increase moisture retention.
Soil water management plays a big role in both agriculture and turf industries, but turf holds secrets to advancements in moisture management technology that haven’t reached agriculture yet. Agricultural wetting agents are here and ready to help farmers manage water and keep moisture in the soil.
As the heat of summer nears, so does the threat of fungal diseases infecting turf. Planning a fungicide application with adjuvants based on environmental conditions and the turf ecosystem can improve fungicide effectiveness.
Fungicides are an important part of plant health, protecting crops from disease. Corn tar spot, southern corn rust, and frogeye leaf spot are a few diseases that can be costly if not treated with an effective fungicide application. Planning an application with adjuvants specifically targeting these diseases is imperative to reducing disease pressure.
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