Several challenges exist to maximize the potential of interseeding cover crops. One issue related to interseeding is the impact of the preemergent herbicide application on the establishment of the cover crop approximately 6 weeks later. We have initiated a study to assess the impacts of various common herbicides on the establishment of the ryegrass, red clover, and white clover seeded at sidedressing. Our initial results were encouraging with successful establishment under most of the herbicide regimes. More evaluation of this issue is necessary before we can make recommendations. It may be that a reduced rate preemergence program followed by a non selective glyphosate or glufosinate application at sidedress may be the optimum solution.
Another weed management issue is the termination of the cover crop. One of the most successful cover crops, ryegrass, can be difficult, but not impossible to kill in the spring. Careful attention to glyphosate rates is necessary to effectively terminate the crop.
Interseeding would also be an additional cost to the producer, but if the seeding could be combined with another trip across the field, then this cost could minimized. And if the potential benefits can be documented from nutrient savings, increased yield of corn on corn, additional revenue from stover or forage, and decreased runoff and leaching, then cost of establishment will be less of an issue.