The Yoshino cherry tree (Prunus x yedoensis) is a fast-growing, deciduous tree that belongs to the Rosaceae family. Celebrated during cherry blossom festivals in Macon, Georgia, and Washington, D.C., this cherry tree is known for its delicate white to pink blossoms that bloom before the leaves develop. The Yoshino cherry tree is native to Japan, China and Korea. While the Yoshino cherry tree has a reputation for being pest resistant, it is still susceptible to several diseases.
Cherry shothole, also called cherry leaf spot, is a fungal disease (Blumeriella jaapii) that weakens the tree and reduces its flowering. Shothole causes small brown or purple spots to form on the leaves. The centers of these spots often fall out, giving the tree a "shot hole" appearance. The shothole pathogen overwinters in fallen leaves. Control includes raking and burning the fallen leaves before spring winds and rains can spread the fungal spores.
Black knot is another common Yoshino cherry tree problem. Caused by the Apiosporina morbosa fungus, this disease causes black knots to develop on branches and twigs. These knots start out soft and green, but harden and darken as the disease matures. Older knots are sometimes partly covered with a white or pink fungal growth. Untreated cherry trees bloom poorly, lose vigor and eventually die. The fungus overwinters in the knots on branches or twigs, and the fungal spores are spread by the wind. Infected areas should be pruned out as soon as possible.
Witch's broom is a fungal infection (Taphrina wiesneri) that causes branches to form large tufts that look similar to straw brooms. Infected branches have fewer flowers and leaf earlier than healthy branches. The brooms don't bear any fruit, and the base of the stem is often thicker than the actual branch. The affected leaves turn red and often have white fungal growths on the under suface. Control is achieved only by pruning out the witch's broom.
Powdery mildew is a fungal disease that often appears on the stems, leaves, flowers and buds of Yoshino cherry trees. Powdery mildew looks like a fluffy, light gray or white coating of dust. This dust is actually the fungal threads, called mycelium, and fungal spores, which are called conida. Powdery mildew is prevalent during cool and humid weather. Young Yoshino cherry trees are more susceptible to damage than mature trees. Powdery mildew is controlled by pruning out the diseased plant tissue and applying fungicide to the rest of the tree.
Verticillium wilt is caused by a soil-borne fungus (Verticillium dahliae). Mild verticillium wilt symptoms include yellowing foliage, brown leaf edges, shoot or branch dieback, and sudden wilting. Severe symptoms include red leaf color, total dieback and curling leaves. A lethal case of verticillium wilt causes the entire plant to collapse. Verticillium wilt symptoms are most likely to appear during hot weather conditions late in the summer.