Herbicide History Determines Seed Purchases Back »

Figure 1. Atrazine injury on oat. Browning starts on older leaves at the leaf tip and progresses toward the stem. Photo courtesy of R. Klein, et al.

Written collaboratively by Sara Berg and Gared Shaffer.


Although 2016 row-crop harvest is still underway, many seed suppliers have started promoting ‘early bird’ incentives on next year’s seed purchases. We all like a good deal when we see one, but it’s important to keep track of field history, and think about your future crop rotation before making decisions.

Checking Field History

With the lag in grain markets over the past several months, you might be considering changing your rotation by adding a crop, or maybe you’d like to try out cover crops. This may be a great choice for the agronomics of your farm, but don’t forget to double check your field history.

Rotation Restrictions

Many herbicides have rotation restrictions following application; if a product has a restriction, it is always stated on the label. For example, adding oats as a third crop to an existing corn/soybean rotation is great from a soil health and diverse plant environment aspect, but if a fomasafen product (Flexstar®) was sprayed the previous season, there is an 18-month rotation restriction before oats should be planted. A failure to realize this before an oat crop is planted could be disastrous. The same caution should be taken if a change in herbicide program occurs as well. University of Wisconsin Extension and Michigan State University Weed Science have provided rotation restriction tables that summarize many cover crops, common cash crops, and herbicides with the associated rotation restriction.

Other Considerations

Of course many other factors should go into making rotation or chemical program changes such as potential for disease, insect pressure, fertility needs, soil health, grazing impacts or restrictions, and of course, marketing and economics. For more information see the links above or contact Sara Berg or Gared Shaffer.

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