Wheat (IMAGE) Michigan State University Caption Once upon a time, it was thought that crop diseases affected only crops. New research shows, however, that a common wheat virus can spread and harm perennial native grasses. Credit Photo by Layne Cameron Usage Restrictions None 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.