Japanese weeping cherry trees in full bloom make a dramatic statement in the garden. Thousands of showy pink-white blooms cover the entire tree as it trails to the ground. Weeping cherry trees work well as specimen trees. They require full sun to bloom well, and they grow in USDA hardiness zones 5 to 8. While fairly low-maintenance, the trees can be affected by disease.
Black knot is a fungus that grows exponentially during wet spring weather. The disease causes hard, black, swollen lumps, called galls, on the twigs and branches of the Japanese weeping cherry. The knots cut off the flow of nutrients and water to the branches, leading to wilting, stunting and dieback. The knots can kill the tree if the infection is severe. Black knot can be controlled by removing and destroying infected twigs and branches when the tree is dormant. A general fungicide sometimes controls the disease.
Silver leaf is a fungal disease that appears as a silver sheen on infected leaves. The first symptoms are dying twigs and branches, with the leaves turning brown in the middle and at the edges. As the fungus spreads, it can kill branches or the entire tree. Prune your tree at the first sign of silvering, destroying all diseased pieces. There is no chemical that can control silver leaf.
Cherry Leaf Spot
The cherry leaf spot fungus affects Japanese weeping cherry’s leaves, twigs and stems. It is commonly found in areas with humid weather. Symptoms include leaves turning yellow, except for dark green spots. The leaves may drop prematurely, and white patches may appear on the bottom of the leaves in the middle of the dark spots. A general fungicide can control leaf spot, as can raking and destroying any fallen leaves.
Bacterial canker is caused by bacteria. The disease has symptoms similar to leaf spot. But bacterial canker produces cankers that ooze a gummy substance during late spring and summer. Spots on infected leaves are dark brown and often surrounded by yellow. Outbreaks of bacterial canker generally occur after cool, wet weather. To control bacterial canker, remove diseased branches when the tree is dormant and spray with a fungicide that contains basic copper sulfate in the fall.