Peach yellows

Peach yellows is a severe plant disease caused by a phytoplasma, a type of wall-less bacterium that lives in the plant's phloem tissue. The disease causes systemic disruption of the host's physiological processes, leading to stunted growth, nutrient imbalance, and eventual death of the tree.

The primary hosts of this disease are various species of the Prunus genus. Peach and nectarine trees are the most susceptible, but the infection also affects plums, apricots, and almonds. The presence of these hosts in proximity significantly increases the risk of an outbreak within a commercial or private orchard.

Symptoms are distinct and progressive. Foliage often exhibits premature yellowing and drooping, followed by the appearance of thin, stunted, and upright shoots known as «witches' brooms». Fruits on infected trees often ripen prematurely, appearing small, bitter, and distorted with reddish-purple spots on the skin.

Transmission occurs primarily through the plum leafhopper, Macropsis trimaculata. These insects feed on the sap of infected trees, acquiring the phytoplasma, and then introduce it into healthy trees during subsequent feeding sessions. The spread is facilitated by warm climates and high insect population densities during the growing season.

There is no known cure for infected trees. Once a tree tests positive or shows clear symptoms, it must be removed promptly and destroyed by burning to prevent further spread of the pathogen. Prevention strategies focus on utilizing certified virus-free nursery stock, controlling the leafhopper population through regular insecticide applications, and strictly adhering to quarantine protocols.

• Immediate removal and destruction of infected trees
• Use of disease-free certified nursery material
• Integrated pest management targeting plum leafhoppers
• Regular inspection of orchard health
• Removal of wild Prunus species in the vicinity