Growing to a height of about 50 feet, the weeping willow (Salix babylonica) is an imposing tree that is cultivated for the sweeping, cascading habit of its branches. Though the weeping willow is susceptible to a host of problems, many gardeners still find the tree to be worth the effort to keep it in good shape.
Weeping willow is susceptible to a long list of pests, including the willow and poplar borer, and both armored scale and soft scale. The black, bristly willow borer chews bark and new shoots, boring holes into the bark and weakening the overall tree. Symptoms include holes in the tree and a fine dust around the holes. Scale may appear as a cottony, soft mass (soft scale) or as a tough, bumpy mass (armored scale). Scale sucks nutrients from the tree, and may appear on leaves or on bark. A scale infestation may cause cracked, bleeding bark or excess branch breakage.
Common willow diseases include root rot, which can infect the tree's root system and cause overall health decline, and willow scab, a fungus which kills new growth and causes cankers on the tree. Fungal infections can usually be battled by pruning and destroying diseased branches. Willow trees should be fertilized frequently to help keep the plant healthy against disease. Other less serious diseases include powdery mildew, which causes a dusty white coating on foliage, and rust, which causes spots on leaves, occasionally killing leaves. Fallen diseased leaves should be collected and destroyed to keep them from re-infecting the tree or other healthy trees.
The weeping willow is not a low maintenance tree. Weeping willow trees have weak, brittle wood that is prone to breakage, especially during storms. The tree sheds leaves, twigs and branches constantly, leaving a mess below it that is unsightly and a hassle to clean up on a regular basis. The amount of debris under the tree also makes it extremely difficult to garden under, which may be unacceptable for those with limited yard space. Regular pruning is necessary to remove unhealthy branches and to promote a strong structure for the tree. Always seeking water, the deep roots of the plant may clog sewer and water pipes on the property.