Plum trees (Prunus) are deciduous fruiting trees belonging to the rose family (Rosaceae). Native to North America, Asia and Europe, the plum tree prefers well-drained, drier soils in partly shady to fully sunny locations. Shot hole disease commonly affects plum trees.
A bacterial pathogen (Xanthomonas arboricola pv. pruni) causes plum tree shot hole disease. The pathogens overwinter in infected twigs and spread by splashing water, infected gardening tools or insects.
Initial symptoms include tiny, water-soaked spots forming on the plum tree leaves. These spots turn brown or purple as the disease progresses.
Infected leaf tissue weakens and falls out of the leaf, leaving a distinct hole. Leaves with several holes tend to turn yellow or drop from the branch.
Affected twigs often form lesions, while infected fruit develop sunken, brown spots.
Preventive measures include removing and discarding fallen plum tree leaves. Gardeners should avoid watering plum trees using overhead irrigation methods.
Shothole borers (Scolytus rugulosus) feed on plum tree leaves, often causing holes similar to those triggered by shot hole disease. Copper spray injuries and earwig infestations also cause similar symptoms.