Shot hole

Shot hole disease, caused by the fungus Wilsonomyces carpophilus, is a severe fungal infection affecting stone fruit species worldwide. This pathogen specifically targets plant tissues, leading to lesions on leaves, buds, shoots, and fruits, which significantly reduces the tree's health and yield potential.

The disease frequently attacks essential commercial crops, including peaches, apricots, cherries, and almonds. The infection often leads to premature defoliation and severe damage to developing fruit, causing scabs and deformities that render the produce unmarketable in an orchard setting.

The diagnostic symptom is the appearance of small, round, reddish-brown spots on the leaves. As the infection progresses, the dead tissue within these spots dries and falls out, leaving small, clean-cut holes, which gives the disease its common name. In severe cases, twigs may develop sunken cankers accompanied by gummosis.

Development of the disease is highly dependent on environmental conditions, particularly moisture. Spores are spread primarily by splashing rain and overhead irrigation during spring and autumn. The fungus survives unfavorable conditions as mycelium or spores within infected buds and bark cankers, ready to germinate when temperatures rise.

Management strategies emphasize reducing inoculum sources through rigorous sanitation and timely chemical applications. Copper-based fungicides are standard for dormant season treatments, while localized applications during the growing season are crucial for managing outbreaks in high-humidity areas.

• Pruning out infected branches to reduce the pathogen population.
• Improving air circulation through proper tree canopy management.
• Applying fungicides during the dormant and early flowering stages.
• Removing and destroying all fallen leaves and infected debris.