Cultural, chemical, and mechanical options are available to terminate cover crops prior to planting the next cash crop; below is the latest information from around the Midwest.
Cover Crop Termination Guidelines for Unfavorable Spring Weather Conditions
provides helpful tips for thinking through your options when the weather doesn’t go according to plan.
Managing Cover Crop Profitably (SARE Handbook Series Book 9) by Andy Clark (2007, 3rd ed.) is a good resource for getting started with cover crops.