Dead Branches on a Willow

Identification

• Willow trees are susceptible to cytospora canker caused by Valsa sordida. The fungus commonly enters trees through damaged bark and twigs. Most willow tree species are prone to the disease.

Damage

• Initial symptoms include the appearance of sunken, elongated and discolored patches on infected bank. There is splitting of bark along the canker margins. Often the fungus kills whole twigs without the presence of visible cankers. Infected sapwood and bark turn brown, yellow, gray or black. Wood becomes odorous and wet as it rots. Entire branches are killed as fungus spreads.

Management

• Keep trees in good health to resist fungal infection. Obtain trees from reliable sources and use resistant varieties. Avoid wounding trees. Prune infected areas to several inches below the cankers. Remove and destroy severely infected trees.