Shot hole disease

Shot hole disease, caused by the fungus Wilsonomyces carpophilus, is a common and destructive fungal infection that affects a wide variety of stone fruit trees. This pathogen is globally recognized for its ability to cause necrotic spots on leaves, leading to the characteristic appearance of small holes in the foliage.

The disease primarily impacts stone fruits, including peaches, apricots, cherries, and plums. It is a versatile pathogen that attacks nearly all aerial parts of the tree, such as buds, twigs, blossoms, and fruits, often causing significant aesthetic and physiological damage to the host plant.

Symptoms are most visible on leaves as circular spots that start as reddish-purple dots. As the affected tissue dies, it eventually falls out, leaving small holes in the leaf blades. On fruits, the disease manifests as scabby, sunken lesions, while twigs may show signs of cankers and gummosis.

The development of the fungus is heavily dependent on environmental conditions. It thrives in cool, moist, and rainy weather, which promotes the dispersal of spores. The pathogen overwinters as mycelium within infected buds, bark cankers, and debris, allowing it to re-emerge as a threat every spring.

Effective control requires an integrated approach that includes strict sanitation practices. Growers should remove and dispose of infected twigs and fallen leaves to reduce inoculum levels. Chemical control involves the application of appropriate copper-based fungicides or synthetic systemic treatments, scheduled carefully before the infection period begins to protect developing plant tissues.