With the cool wet spring that has occurred in the Bismarck/Mandan area, residents are seeing many ash trees lose their leaves. The cause of the problem is Ash Anthracnose; a fungal problem that occurs when the weather is cool and wet.

Along with the leaves dropping, the leaf may have brown “blotches” and distortion of the leaf. Severe cases may cause twigs to die. In most cases this disease will not cause permanent damage to large mature trees but may stress younger trees that have experienced other stress factors in the last couple of years, such as root damage, drought or flooding.

Although there are fungicides that will prevent Ash Anthracnose, it is too late this year for chemical applications to be effective. The best thing home owners can do at this point is use cultural control measures such as raking up and removing fallen leaves and twigs from infected ash trees to help reduce the amount of fungi that survive from one season to the next. The fungal spores remain alive throughout the winter in this debris material. If the following year brings another cool, wet spring the spores will cause infection in susceptible trees.

For more information on Ash anthracnose and other pest problems check out the Bismarck Forestry link below.