Early control and smart herbicide use help protect crop yield and soil health
Weed management is an essential part of successful crop production. Weeds compete with crops for water, nutrients, sunlight, and space. If they are not controlled early, they can reduce yields and increase long-term problems in farm fields.
In corn, weeds can affect yield at a very early growth stage. Research shows that yield losses can begin as early as the V2 stage. For best results, weed control should start before V2 and continue until at least V14. During this time, corn plants are most sensitive to competition, and early action helps protect yield potential.
“If we are spraying at that V2 stage in corn and that would be similar to V2/V3 soybeans, we have a pretty good chance of getting coverage across that whole 30-inch row,” said Troy Deutmeyer, Pioneer field agronomist.
“When we are spraying early, the weeds are going to be small if there are any emerged, and then the other thing is our crop is not going to take up much herbicide, therefore our chance of having a crop response to the herbicide becomes much smaller,” said Troy Deutmeyer.
Soybean crops also need close attention in their early growth period. The first four weeks before canopy closure are critical for weed control. While a closed canopy helps suppress weeds naturally, farmers should continue to monitor fields to prevent late-emerging weeds from spreading.
One effective approach is using a sequential weed management program. This involves applying preemergence herbicides followed by postemergence herbicides. Preemergence products help stop weeds before they emerge and allow more flexible timing for later applications. This approach also reduces weed seed production and improves overall control.
If preemergence herbicides cannot be used, postemergence herbicides should be applied as early as possible. Using recommended rates, adding residual herbicides, and following label instructions are important steps. High-quality adjuvants and follow-up treatments may be needed to control weeds that escape early sprays.
“The best program you can use is to mix it up every time you’re in that crop,” said Bradley Mason, Pioneer senior sales agronomist. “So, you shouldn’t be going back-to-back-to-back with those [same] herbicide modes of action. We need to make sure we continue to mix them up, to make sure we continue to have those modes of action in the future.”
Herbicide resistance is a growing challenge. Resistance can develop quietly and may suddenly affect a large portion of the weed population. Farmers can reduce this risk by rotating crops, using different herbicide modes of action, and avoiding repeated use of the same products.
Environmental conditions also play a role in herbicide performance. Dry weather can increase the risk of herbicide carryover, which may harm the next crop plant. To avoid injury, farmers should always follow label guidelines and consider rotation intervals.
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