Leaves curl upward, gradually turn completely yellow, and drop from the tree.
The only other common disorder on peaches that produces similar symptoms is nitrogen deficiency. However, nitrogen deficiency generally causes more uniform yellowing throughout the tree, and the red spots on leaves are more uniformly round. X-disease does not appear to spread from one infected peach tree to another. Sweet cherry trees can also carry X-disease and provide inoculum for infecting nearby peach orchards. Ever since it was discovered in Connecticut in the 1930's, X-disease has been a somewhat cyclical disease in areas where chokecherries are prevalent.