Disease Problems On Willow

The main two problems with the willow are these diseases:

Willow Scab

Willow scab is caused by the fungus Venturia saliciperda and causes scab-like, black lesions to form on the shoots. The young shoots and leaves are most susceptible to the fungus and, once afflicted, can die within a very short time. Early signs of willow scab include masses of olive green spores along the veins of the underside of leaves. Willow scab often occurs with black canker on willow trees. The fungus continues to reside on the destroyed twigs over the winter and becomes the main reason for infection on new growth in the spring. Willow scabs can be controlled with a combination of chemical and cultural treatments. Chemical control includes the use of fungicides to reduce infection and pruning of infected twigs and stems is recommended to reduce the severity of the disease.

Black Canker

The willow trees that have willow scabs often have black canker as well. Black canker results from the fungus Glomerella miyabeana and afflicts willow trees later in the season. The disease causes cankers to appear on the larger stems of the tree and leaves. Tree foliage starts to show dark brown to black lesions or spots. As the disease spreads towards the stem it causes leaves to shrivel and die. Gradually the fungus colonizes the stem tissue and starts to create dark brown and black cankers. Black canker can be controlled with the timely application of recommended fungicides and pruning of the infected limbs.

On a large scale the best organic control is to use a Bordeaux mixture which you can mix yourself please follow this link for some more details: http://en.wikipedia.org/wiki/Bordeaux_mixture