Weeping willows are a fast-growing ornamental tree with drooping, pendulous branches. Though weeping willows are a brittle, soft wood, the tree will root so easily that downed weeping willow branches will often put out new roots to form new trees. Willow bark can be treated to make a form of aspirin as well as a rooting hormone. Though weeping willows can suffer from a wide range of maladies, they can usually be nursed back to health. The key to curing a sick weeping willow is to diagnose the problem early and take steps to treat the tree before it becomes too sick to survive.
Pick a pendulous branch from a weeping willow tree and examine the leaves. Yellowing, stunted leaves are a sign of leaf scab. Leaf scabs often leave a mass of olive-colored spores on the underside of the leaves. A dusty residue on the leaves may be a sign of powdery mildew. Black spots on a leaf may be a sign of leaf spot.
Climb a ladder to reach into the canopy of your willow tree. Examine your willow branches for signs of disease. Leaf scabs may turn the twigs at the end of branches black. Black canker will leave cancerous sores on the branches of a willow. The two diseases often occur simultaneously on a weeping willow. Powdery mildew will leave a dusty white residue on the branches.
Mix a solution containing one part bleach and nine parts water. Soak pruning tools such as hand saws and branch loppers with this solution. Remove branches affected with leaf scab and black canker to remove the diseases from a willow. Soak your tools in between removing each affected limb to stop the spread of these diseases.
Watch your weeping willow for signs that powdery mildew or leaf spot has reemerged. If pruning the tree to remove affected branches does not stop the spread of the mildew or leaf spot, you must spray the tree with a fungicide. Commercial fungicides may be purchased pre-mixed in spray bottles and sprayed over your tree's canopy.