Current cool temperatures increase the risk of failures in terminating cover crops. While cereal rye continues to grow during these conditions, activity of herbicides is reduced.

Translocation of glyphosate to growing points is reduced under cool temperatures, slowing activity and increasing the potential for control failures. It is generally recommended to avoid applications when nighttime temperatures fall below 40 degrees F, and temperatures at application should preferably be at least in the mid-50s with clear skies. Based on current forecasts, herbicide applications to terminate in many areas of Iowa should be delayed until more favorable conditions exist.