Sampling Volunteer Cereal Rye In Wheat (IMAGE) American Society of Agronomy Caption Cover crops must be rolled at the right time, or they might set seed and cause trouble later. Research technician Mark Dempsey and undergraduate research assistant Samantha Bollinger sample how much cereal rye is in a winter wheat field. Credit Clair Keene Usage Restrictions Please use with story only. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.