Spotting on plum tree (Prunus salicina) leaves is an indication of a problem the tree owner needs to address. Most causes for spotting result from fungi or bacteria attacks on the tree, according to North Dakota State University. It is important to examine trees often for infected area treatment or removal, preventing the spread to the remainder of the plum tree.
Raise plum trees in growing zones 5 though 9. Areas with too much moisture lead to increased potential for leaf spotting problems. Moderately dry soil and plenty of sun exposure are ideal geographical locations.
Spotting on plum tree leaves often means that entire plum tree orchards can become infected. Regular examination of trees and controlling the cause of the spotting is imperative to reduce the possibility of losing trees or large quantities of plum crops.
Growing plum trees in dry climate regions is the best prevention for spotting on leaves. Humidity and wet conditions lead to the plum tree's susceptibility to diseases that cause the spotting. Some fungus diseases respond well to benomyl fungicide solutions, according to North Dakota State University.
A white powdery substance, later followed by black spotting, is caused by powdery mildew fungus (Podosphaera oxyacanthae). Bacterial spot (Xanthomonas pruni) and shothole (Pseudomonas syringae) create water spots that turn from brown to black on the plum tree leaves. Cherry leaf spot (Coccomyces hiemalis) fungus forms very small yellow spots that eventually turn brown.
Fungus diseases that cause leaf spotting on plum trees produce spores that infect the surrounding soil. The fungus spores are also airborne. Early detection and control is imperative to prevent loss of entire orchards and crops.