Abstract
The leafhopper C. montanus (Van Duzee) acquired the agent of the Green Valley type of X-disease from cherry and transmitted it to celery and to healthy Mazzard cherry seedlings. Transmission rates to celery increased throughout the growing season from 0 in April to a high of 25% in Aug. Cherry may be a source of inoculum for spread to cherry and other host plants. C. montanus did not transmit the agent of the peach yellow leaf roll type of X-disease from peach in field and greenhouse experiments.