When it comes to applying pre-emergent herbicides, many no-tillers may hesitate if the soil is frozen, especially in colder regions. The thought of spraying on frozen or nearly frozen ground might seem counterintuitive, but under certain conditions, it can be an effective strategy.
Brian and Darren Hefty, fourth-generation farmers, agronomists and hosts of Ag PhD, spoke at the Commodity Classic show in Houston about the advantages of spraying pre-emergent herbicides on semi-frozen soil.
"The biggest advantage is you get to spread the workload in addition to the better control you have,” Brian says. We just tell you, don't spray in January when it's going to be frozen for two months or anything like that."
If the ground is frozen in the morning, but thawing in the afternoon, that is the perfect time to spray pre-emergent, according to the Heftys.
Why Spray on Semi-Frozen Soil?
Spraying pre-emergent herbicides when the ground is firm reduces the risk of tracking up the field, which is a common concern with wet or thawing soil. Applying herbicides when the ground is still partially frozen gets the job done early, distributing the workload more evenly throughout the season.
One of the key benefits of spraying on semi-frozen soil is the potential for improved weed control, according to Brian.
“We will go out there and spray on days that are below 32 degrees, so the ground is firm,” Brian says. “We aren't tracking up the field. I know it sounds nuts and you don't want to spray it on frozen ground, but here's what I want you to think about. We're just out there spraying. The ground is firm, and it thaws in the afternoon. When we spray early, we get more of a chance for rain or snow to work it down in the ground.”
Pre-emergent herbicides are designed to remain effective even in less-than-ideal conditions. Unlike some herbicides that can break down through photodegradation or evaporation, the Heftys say these herbicides do not lose their efficacy under the cold conditions typical of semi-frozen soil.
Considerations for Safe & Effective Application
It’s crucial not to apply herbicides too early. The best practice is to time the application so that it coincides with conditions where the soil will thaw soon after, ensuring effective herbicide incorporation, according to the Heftys.
“Don't spray in January when it's going to be frozen for 2 months,”Brian says. “Don't spray a month or 2 before you're going to plant if it's an area that might flood out or have any problems like that. And if you can't keep your sprayer in a heated shop, you probably don't want to be spraying in March, when many times, the nighttime temperature is 20 degrees.”
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