CAUTION NEEDED: Any herbicide with a 4.5-month or longer rotation restriction applied in corn or soybeans has the potential to injure winter wheat.

Review herbicide program before winter wheat

Consider corn and soybean herbicide rotation restrictions if you're planning on planting winter wheat.

More than a few eastern Nebraska growers are considering planting winter wheat this fall. If you are one of those farmers, you should start planning or reviewing your 2018 corn and soybean herbicide programs with next fall in mind.

Many herbicides have rotation restrictions, the minimum time required after the herbicide application and before another crop can be planted. Any herbicide with a 4.5-month or longer rotation restriction applied in corn or soybeans has the potential to injure winter wheat next fall and thus should not be used this spring. This is to safeguard against herbicide residual activity in the soil that could potentially damage winter wheat planted this fall.

For that field or fields where you intend to plant wheat this fall, here are some suggestions for your corn and soybean herbicide programs.

Corn herbicide programs
A variety of products that can be used after corn planting but before crop emergence will not affect winter wheat this fall because they have less than a four-month rotational restriction for winter wheat. They include Acuron, Anthem Max, Balance Flexx, Callisto, Corvus, Hornet, Instigate, Outlook, Resicore, Sharpen, SureStart and Verdict. All other products, especially those that contain higher rates of atrazine, should not be used as they have rotational restrictions longer that 4.5 months, some as much as two cropping seasons, so choose wisely. Likewise, check the rotation restrictions of herbicide products used for postemergence applications in May and June.

Soybean herbicide programs
Preemergence soybean herbicides that are safe for winter wheat include Afforia, Anthem Maxx, Authority Assist, Authority First or Authority Max, Authority XL, Envive, Enlite, Fierce, First Rate, Latir, Outlook, Pursuit, Torment, Valor, Valor XLT, Warrant and Warrant Ultra. As we move into postemergence products with residual during June, you need to check the label again for rotation restrictions.

Check for yourself
The rotation restrictions can be found on the herbicide label and should be checked each year since they can change. You can also view labels online before buying your herbicide products. Information is also available in Nebraska Extension’s 2018 Guide for Weed, Disease, and Insect Management in Nebraska, which includes rotation restrictions on Pages 172-185.

The guide also provides herbicide efficacy tables for the most common weeds for each herbicide, including the herbicides listed in the corn and soybean programs described above.

In addition, for those interested in planting cover crops, including wheat, in the fall a Nebraska Extension NebGuide has valuable information. Herbicide Options for Planting Forage and Cover Crops Following Corn and Soybeans provides information on the planting interval of several cover crops in the fall after applying corn-soybean herbicides in the spring.

This report comes from UNL CropWatch.

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