MONROE, MI -- Overwintering cover crops have provided many benefits to farmers in Monroe County and the western basin of Lake Erie. They hold soil (and nutrients) in place so that neither ends up in the surface or groundwater. They help minimize soil compaction, allow for additional microbial activity in the soil, act as a nutrient “sink” and provide a habitat for wildlife.
Now that spring is here, it is time to kill off those crops so that the 2016 crops can be planted. When not effectively terminated, cover crops can themselves become weeds in the annual grain crops and can slow down soil drying. Cover crop escapes that are allowed to mature and produce seed can be troublesome for more than the current growing season.
Control of cover crops can be done with herbicides, tillage, a crimping tool or even harvesting the cover crops. Some crops such as radishes or oats should have already winter killed and should not require any additional burndown. Some radishes could survive for even a year or two, depending upon the situation.
In general, the smaller the size of the cover crop, the easier it will be to kill. Before choosing a herbicide, consider what winter annual or other weeds might be present. Depending upon the crop to be grown, there might be a label restriction that precludes planting for a certain number of days after a herbicide has been applied.
In general, glyphosate may be the most effective herbicide for most cover crop control. For 2016, there are 60 different glyphosate products for sale in the state of Michigan as listed in the 2016 Weed Control Guide for Field Crops by MSU. They are not all formulated the same, with some requiring various surfactants, such as a non-ionic surfactant at varying rates.
Purdue University has two extension publications available free of charge to help. One is; Successful Termination of Cover Crops, and the other is; Successful Annual Ryegrass Termination with Herbicides.