Mule's ear of peach

Mule's ear is a distinct phytoplasma-induced disease primarily affecting peach trees. The causative agent is a wall-less bacterium that inhabits the phloem of the host plant, systematically disrupting its nutritional transport and development processes.

This disorder is specific to certain stone fruit species, with peaches being the most common host. The pathogen causes a significant physiological imbalance, leading to long-term structural changes that manifest during the active growing season.

The primary clinical symptoms include severe leaf malformation where leaves appear elongated, thickened, and coarse, resembling the ears of a mule. Furthermore, the tree exhibits shortened internodes and stunted growth, often leading to a rosette-like appearance of the terminal shoots.

Development and spread are facilitated by insect vectors, particularly leafhoppers, which transmit the phytoplasma while feeding on the phloem sap. The disease can also be introduced into an orchard via infected grafting material or nursery stock, making sanitation a top priority.

The overall damage is significant as the disease affects the tree's vigor, reduces fruit set to zero, and compromises the tree's immunity to secondary infections and environmental stress. Since there is no cure, management relies on strict preventative measures, including the destruction of symptomatic trees and the rigorous control of insect populations to minimize transmission risks.