Several thousand acres of cover crops were planted in the Midwest last fall, many by farmers who have not used cover crops in the past. The time to terminate these cover crops is quickly approaching in northern climates and already happened farther south.

Trials completed in Iowa taught farmers and those making recommendations a lot last spring, especially the importance of timely control of winter grains used for cover. In the fall of 2012, several replicated strip trials were seeded with a drill after soybean harvest that compared untreated strips with strips seeded to tillage radish, tillage radish plus oats, tillage radish plus fridge triticale and tillage radish plus fridge triticale plus crimson clover.

The spring of 2013 was extremely wet in Iowa, making it difficult for the triticale to be terminated in a timely manner. Instead, the cover crops strips were terminated just prior to planting. In the limited trials with fridge triticale, there was a negative yield response but it was obvious what was going on.

It’s generally recommended that cover crop containing triticale be terminated 10-14 days before planting to avoid the allelopathic effect of the winter cereals on corn. Soybeans typically are not affected by this.

In the 2012 Iowa trials, strips with tillage radish and the tillage radish annual oats had yield increases compared with no cover crops.

Cereal rye is the most common cover crop that will need to be terminated in the spring, but others like annual ryegrass and triticale may need to be terminated as well.

Extensive information on terminating cover crops can be found in the Purdue University “Terminating Cover Crops” publication.