Stick the landing
Avoid temperature inversions and choose your adjuvants wisely to minimize drift
By Cullen Wiggins, GreenPoint Ag Crop Protection Marketing Manager
When spraying a crop-protection product, it’s more important than ever to stick the landing. With high input costs and increasing scrutiny over off-target movement, making sure that every drop of spray hits its intended mark has never been more critical. Whether you’re applying herbicides across thousands of acres or treating pastureland, the difference between an effective application and one that drifts away usually comes down to two key factors: weather conditions — specifically temperature inversions — and the adjuvants you include in your tank mix.
Let’s start with one of the most misunderstood — yet impactful — environmental factors: the temperature inversion. What is a temperature inversion? Most of the time, air near the ground is warmer than the air above it. However, during a temperature inversion, a layer of cool air becomes trapped beneath a warmer layer above. This stratified air pattern — often occurring during early morning or late evening hours — can essentially “lock” spray particles in place.
Think of a fog hovering over a field or the way smoke from a fire can sometimes hang low instead of rising. That’s a temperature inversion. If you spray during these conditions, your fine droplets may never reach the target surface. Even worse, they can drift for miles in a visible (or invisible) cloud, potentially damaging neighboring crops or environments.
While inversion-related issues have been widely discussed in the context of Dicamba or 2,4-D herbicides, the truth is that any herbicide can be compromised by these atmospheric conditions. Even glyphosate, which rarely causes visual off-target damage, can be adversely affected if caught in an inversion. That means you’re losing active ingredient — and money — into thin air.
Best practices for avoiding inversions This is really a matter of timing. To minimize risk, avoid spraying at dawn or dusk. Wait until the sun has warmed the surface layer — typically 9 or 10 a.m. — and shut things down at sunset. Pay attention to conditions like still air, dew, or fog, which can indicate an inversion is in place. Check the boom height Once you’re sure the conditions are right, there are mechanical issues to consider. One of those is boom height. With Dicamba, there are restrictions put in place that require a boom height of 24 inches above the crop canopy, and that’s a best practice for any crop protection product. This gives any wind less time to have an impact on the spray pattern and keeps the product on target. The sprayer operator should also pay close attention to speed — moving too fast can create wind off the sprayer itself.
A temperature inversion is easy to spot — think of a fog hovering over a field as depicted in the photo above. If you spray during these conditions, the fine droplets may never reach the target surface and are in danger of drifting far off target.
Adjuvants: The unsung heroes of every tank mix Even under perfect weather conditions, herbicide applications need help to be effective, and that’s where adjuvants come in. Think of them as the behind-the-scenes crew that ensures the stars of the show — your herbicides, fungicides, and insecticides — reach their full potential.
Products like WinField United’s InterLock® optimize droplet size for maximum deposition and minimal drift. They chemically alter the spray solution to create more uniform, heavier droplets that stay on target and resist bouncing off the leaf surface or evaporating midair.
Other formulations in the “Lock” family, including MasterLock®, PowerLock®, UltraLock®, and StrikeLock®, combine drift reduction technology with other key benefits, such as enhanced surfactant properties or compatibility with high-performance herbicides. For example, MasterLock is a go-to option for corn fungicide applications because it won’t contribute to arrested ear syndrome — a risk associated with some surfactants applied during VT-R1 growth stages.
Meanwhile, UltraLock is a great fit for growers using Enlist™ herbicide systems, offering tank mix flexibility without compromising on drift control. These adjuvants are not just extras — they are essential tools for safeguarding herbicide performance and ensuring coverage, even under challenging field conditions. Understanding your water and weed targets Before choosing an adjuvant, understand the composition of your water and the biology of your target weeds. Hard water can tie up active ingredients, reducing efficacy. In these cases, conditioners like Class Act NG® help maintain herbicide performance by preventing cation interference and enhancing absorption on the leaf surface.
Similarly, for weeds with thick waxy cuticles or leaf hairs, surfactants or oils like Destiny HC® or StrikeLock® improve penetration and maximize herbicide uptake — especially under hot, dry conditions when leaf surfaces are most resistant.
In a time when every acre — and every drop — counts, don’t leave your results to chance. Visit with your local Co-op or GreenPoint Ag advisor to ensure you’re using the right adjuvants, in the right combinations, under the right conditions. Whether you’re managing pastures, row crops, or custom applications, the path to cleaner fields and better yields starts with smarter spraying.
Correct boom height gives any wind less time to have an impact on the spray pattern and keeps the product on target. The sprayer operator should also pay close attention to speed — moving too fast can create wind off the sprayer itself.
By Mark Johnson,
Contact mark@bigharvestcreative.com