The flowering or ornamental cherry tree features showy pink blossoms in the spring, but the tree is fairly delicate and may be plagued with many problems if not carefully tended. To ward off common problems, keep the flowering cherry watered and fertilized regularly, according to University of Maryland Cooperative Extension. Prune annually to increase air circulation, which naturally discourages bacteria and fungal disease.
Powdery mildew causes a fine white powder on leaves and cherry buds. Gardeners can apply a preventative dose of wettable sulfur or horticultural oil so trees affected with powdery mildew the previous year will not succumb again. Rake up fallen leaves and dispose of them so the fungus cannot overwinter in the soil and re-infect the tree the next year.
Flowering cherry trees affected with leaf spot develop small purple lesions on the leaves. The leaves then develop holes that turn yellow; eventually, affected leaves drop from the tree. To prevent infection the following year, rake up fallen leaves and dispose of them in the garbage bin. Leaf spot may also be treated with a fungicide.
Several insect pests prey on ornamental cherry trees, including aphids, borers, tent caterpillar and scale. Scales may have a soft or hard shell and generally creep along the branches of cherry trees. Difficult to notice due to their small size, they suck nutrients from leaves and twigs.
Aphids are another insect pest that feed on the tree's sap; they produce a sticky substance called honeydew. They range in color from yellow to black and respond well to treatment with insecticidal soap. Borers include certain beetles and moths; they are most effectively treated with insecticides containing permethin.
Cherry trees can develop root rot that will eventually kill them. To protect against root rot, plant the tree in well-draining soil and avoid overwatering. Root rot is difficult to detect in the early stages since initial symptoms occur underground, at the roots. If your cherry tree experiences dieback of twigs or browning of leaves, you may have root rot.