Weeping willow trees are beautiful additions to your home's landscape. If the leaves of your tree are forming brown spots and are yellowing, it may be suffering from willow blight.
Willow blight is a combination of two willow tree diseases: black canker and willow scab. Black canker is a fungus that begins to appear in late spring or early summer as brown spots on leaves. This fungus can continue to grow on twigs and branches infected with willow scab.
Willow Scab and Black Canker
The fungus Venturia saliciperda is the main culprit behind willow scab. It infects new shoots by overwintering on infected twigs. Willow scab often appears after rainy spring weather that keeps tree branches moist. Black canker is caused by the fungus Glomerella miyabeana and grows from overwintering spores on twigs.
One way to avoid the spread of willow blight is to prune away branches infected with the disease. Another preventive measure is to rake up and remove any dead leaves or branches before new spring growth appears. Applications of fungicide can also be an effective preventive measure.