X-Disease is a disease that is associated with peach, nectarine, and cherry trees around the Great Lakes. This disease is characterized by the leaves of affected plants turning a red-yellow color, shriveling, and ultimately falling off.

The cause of this disease is a small organism called a mycoplasma. The spread of the disease is caused by leafhoppers that feed on infected chokecherries, cherries, peach, or nectarine trees and pass it on to other healthy trees.