Why Is My Weeping Willow Thin in the Top?

Age

• The weeping willow (Salix) is a relatively short-lived tree that typically survives no more than 30 years. With this in mind, an otherwise healthy weeping willow can quickly show signs of old age, including becoming thin in the top. Boasting a rounded, weeping crown, the tree normally grows to a height of between 45 and 70 feet with a similar canopy spread. It is not tolerant of urban conditions, a characteristic that can contribute to a lack of vitality.

Water

• A weeping willow that is thin in the top could be suffering from a lack of water. It is moderately drought-tolerant but will lose leaves if deprived of hydration over an extended period of time. The tree does very well in moist soils and should be well-watered to allow it to develop enough vigor to survive and maintain its full, dense crown when periods of drought do arrive. The wood of the tree is weak with broken branches in the crown contributing to the appearance of thinning.

Environment

• A lack of vigor contributes to the decline of the tree and loss of thickness in branches and foliage on the top of the weeping willow. The tree thrives best in U.S. Department of Agriculture plant hardiness zones 2 through 9a and will grow with less zeal in tropical or bitterly cold locales. It enjoys a mixture of full sunshine and partial shade, while adapting nicely to a wide variety of soil, including those with high levels of alkaline.

Pests and Disease

• Insect pests of the weeping willow include caterpillars, borers, aphids, scales and gypsy moths, all of which damage the leaves and branches of the tree, sometimes seriously. High levels of infestation can lead to fallen branches and defoliation of the top and all of the tree. Diseases like root rot contribute to the decline of the tree, while willow scab attacks young leaves. Other diseases of the willow that thin out the tree include willow blight, cankers and a number of fungal diseases.