Each spring your crop is pitted against a range of weeds in a competition for nutrients, moisture and sunlight. I’m talking about those weeds we love to hate: foxtail barley in cereals, kochia in lentils and volunteer canola in soybeans. You can give your crop the advantage by hindering these weeds with post-harvest soil applied herbicides before they even get out of the ground.
This is why soil-applied herbicides have become a critical tool in the progressive farmer’s toolbox. They provide residual control and help fight herbicide resistance by also offering different modes of action. Pssst: if you grow pulse crops and deal with herbicide-resistant kochia or wild mustard, you’ll want to pay attention.
Fall vs. spring
The herbicides Focus®, Valtera™, and Fierce® are applied to the soil surface and require moisture to activate. The amount of moisture required by each differs, which makes late fall the ideal time to apply. Snow melt moves the herbicide further into the soil and impacts the amount of herbicide available for absorption by germinating weeds.
Residual that counts
Controlling weeds early protects against those nasty yield robbers, and enhances your in-crop herbicide application by holding the weeds until you can apply your first in-crop application.
Pro Tips for fall application
- Wait until the ground becomes cool, usually mid-late October just before the snow covers the ground for good.
- Make sure not to use much tillage/soil disturbance after application as this can break the barrier. Ideally, after you spray the only type of soil disturbance is at seeding.
- For best results add glyphosate when spraying an herbicide on the soil in the fall to control any of the perennial or winter annual weeds already present.
- 10 gallons of water is recommended at spraying.
Certain conditions dictate caution, such as sandy soils and droughts, but for the most part soil applied herbicides boast more pros than cons. If you’d like to talk through the benefits, contact your local Cargill agronomist.
Tackle herbicide resistance
Herbicide resistance is spreading, but studies have shown that using products containing multiple modes of action lowers the risk of developing resistance exponentially. Use glyphosate as a standalone pre-burn herbicide no longer!
Soil applied products slow resistance by reducing the selection pressure on post-emergent herbicides. Products like Focus® are great for this because they will target wild oats and cut down the wild oats population you see in-crop as well as expose the weeds to a different chemistry group. Group 1- and 2-resistant wild oat numbers are on the rise, and since we are limited with grassy weed control options, it’s only a matter of time before resistance is present on your farm. Soil applied products containing groups 8, 15 and 3 are useful for controlling group 1- and 2-resistant wild oats.
Focus® is a registered trademark of FMC of Canada. Fierce® is a registered trademark of Nufarm Agriculture Inc. Valtera™ is a trademark of Valent U.S.A. Corporation. Always read and follow label directions.