With planting season coming soon, farmers may want to start addressing the weeds that could already be lurking in their fields. The issue of herbicide-resistant weeds poses a major threat to soybean yields throughout the United States. Armed with a plan, however, farmers can effectively manage herbicide-resistant weeds, according to Larry Steckel, Ph.D., of the University of Tennessee.
“By having a plan up front for weed control and spraying for weeds in a timely manner, farmers can save money and have much more consistent weed control,” Steckel says.
In this interview, Steckel, a row-crop weed specialist and associate professor at the university, discusses the importance of starting planting season with clean fields.
Q: Why is it so important for farmers to begin their planting season with clean fields?
A: The bottom line is farmers have to make sure they are ahead of weeds. If weeds have already emerged before the crop starts coming up, those weeds are going to have a huge advantage. Weeds compete for the same nutrients as soybeans – nitrogen, light and water – and typically weeds get first dibs. We have documented Palmer amaranth going from a small seed to 8 inches tall in 13 days. Soybeans would be lucky to be a couple of inches tall at that point – there is really no contest. So farmers have to start out clean with clean fields; if they don’t, weeds can easily outgrow their crop.
Q: What should farmers be thinking about now to prevent weeds from popping up in their fields this year?
A: Farmers should be preparing to apply their burndown applications. Since we have had a hard winter, winter annuals will not have as much of a head start on soybeans, giving farmers a chance to effectively control the weeds more so than last year. Glyphosate-resistant marestail and ryegrass have caused the most problems in the past, but this year’s winter weather should make them easier to control.
Q: What are the best weed-management practices for farmers to use to achieve a clean field before planting?
A: Here in Tennessee, we try to start applying the first burndown applications the first part of February, when weeds like horseweed and marestail are still relatively small and easier to control. Typically, you can get by with 8 ounces of dicamba or 24 to 32 ounces of 2-4D. Once you get closer to planting season, you have to use greater amounts or you have to start applying other methods to get any kind of consistent control.
Q: What weed-management tips do you have for after planting?
A: The key to resistant pigweed species is overlapping residuals. After applying the residual with the first burndown application, about 14 to 20 days out, we are applying another residual and trying to activate them. Ideally, both residuals activate and start doing their job fighting weeds. The key is keeping the weeds from coming up in the first place and that’s where overlapping the residuals comes into play.
Q: The checkoff has led an industry-wide weed-management program called Take Action. How do you think farmers can benefit from the materials being developed as part of that program, such as weed-identification and herbicide-classification charts?
A: I have had a great response from the materials. They have been a great educational tool and an impactful resource for anyone who sprays — farmers and retailers both. The posters can easily be hung in shops or wherever a farmer prefers, and then they conveniently have herbicide modes of action to refer to. We have to start using more than one effective mode of action in order to fight herbicide resistance. Educational materials that the checkoff creates, such as these posters, are a great way to spread that message.
Q: How can the use of cover crops help farmers with weed management?
A: Using cover crops is a much more sustainable system than what we can do with herbicides only. We’re seeing that cover crops are helping us eliminate a whole round of herbicide application in marestail. Usually you have to burn down marestail twice. But with cover crops, you only have to burn down the cover crop once, because if you have a good stand of cover crop, you won’t have much marestail, if any. We’re also seeing great control on pigweed.
Source : unitedsoybean.org