When it comes to controlling herbicide-resistant weeds in your cornfields, it’s important to have a lot of tools in your toolbox. A program approach with preemergence and postemergence applications that include multiple modes of action and residual activity is one of the best tools you can use. However, it’s not the only one.
Farmers know cultural practices can be very useful for keeping difficult weeds at bay. One of those practices is crop rotation, and there is one big benefit it can bring to a weed control program.
Steve Cromley is a retail product agronomist for Brevant® seeds. He says the No. 1 reason crop rotation is beneficial to a corn weed control program is that it helps you manage herbicide resistance.
“Crop rotation itself does not prevent herbicide resistance, but it does make resistance management and prevention easier,” Cromley says. “Having multiple crops in the rotation provides the farmer with more herbicide options, making it easier to select multiple modes of action that will effectively control weeds.”
“Having multiple crops in the rotation provides the farmer with more herbicide options, making it easier to select multiple modes of action that will effectively control weeds.”
Being able to apply, say, soybean herbicides one season and then corn herbicides the next keeps weeds from adapting to any one mode of action too quickly. This also reduces the likelihood weeds will develop resistance to the herbicides.
“Crop rotations provide more herbicide choices and application timing to control troublesome weeds. It’s important to use multiple effective modes of action to slow herbicide resistance,” Cromley says. “In a single crop system, overreliance on the same modes of action can lead to herbicide resistance. Having multiple crops in the rotation provides the grower with more herbicide options to select multiple effective modes of action.”
And the benefits of crop rotation aren’t limited to weed control. Cromley says rotating from corn in a field one season to soybeans in that field the next season has other advantages.
“Corn and soybeans grown in rotation tend to have higher yields, reduced pest pressure and improved soil health. Corn grown after soybeans usually yields more than corn grown after corn,” Cromley explains. “Soybeans grown after soybeans usually yield less than when grown after corn. Pest pressure reduces yield when allowed to build on one host.”
“Corn and soybeans grown in rotation tend to have higher yields, reduced pest pressure and improved soil health.”
While there are a lot of benefits to crop rotation, Cromley says, there are some considerations for farmers.
“When considering a new crop rotation, it’s important to think about the added cost to the operation. Will equipment need to be purchased?” Cromley asks. “Can I plant and harvest the crop with current machinery on the farm? If considering another crop not commonly grown in the area, is there a stable market?”
Cromley says these are all questions you’ll want to ask your ag retailer or other trusted advisers when planning a new crop rotation. He says it’s entirely possible a rotation won’t work for your farm or fields. However, it’s a good tool to consider if you’re having trouble with difficult, herbicide-resistant weeds.
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