See:
Cherry (Prunus spp.) - Prunus Necrotic Ringspot
Peach (Prunus persica) - X-Disease
Peach (Prunus persica) - Plum Pox (Sharka)
Cause There have been very few peach virus or virus-like diseases from Oregon diagnosed by the OSU Plant Clinic. Prunus necrotic ringspot virus has been found. Peach wart disease (unknown) and X-disease (Candidatus Phytoplasma pruni) have also been found. It was suspected that some peach samples had peach calico (peach latent mosaic viroid) or prune dwarf virus but were not confirmed.
The old Index of Plant Diseases (Ag handbook #165 from 1960) indicated the following for Idaho: peach calico virus (most likely peach latent mosaic viroid), peach mottle virus, peach wart virus, as well as X-Disease.
The following virus and virus-like problems have been found in peach by the Prosser virus testing lab: cherry virus A was common among peach samples followed by prune dwarf virus, prunus necrotic ringspot virus, X-disease phytoplasma, pear decline phytoplasma (transmitted by the pear psylla from pear orchards), hop stunt viroid (HSVd), nectarine virus M (asymptomatic), nectarine stem pitting associated virus (largely asymptomatic), plum bark necrosis stem pitting associated virus (asymptomatic), peach latent mosaic viroid (asymptomatic) and cherry necrotic rusty mottle virus.
The pear decline phytoplasma in peach results in a disease called peach leaf yellow leaf roll and has symptoms that are similar to X-disease. Symptoms include general chlorosis, leaf tips and margins roll downward, and mid-rib and lateral veins are enlarged and swollen. But unlike X-disease, leaves are normal in size and there is no shotholing. Trees also decline and die more rapidly with this phytoplasma than with X-disease.
Reference Hadidi, A., Barba, M., Candresse, T., and Jelkmann, W. 2011. Virus and Virus-like Diseases of Pome and Stone Fruits. St. Paul, MN: APS Press.