Ash anthracnose

photo of ash anthracnose effects.

The cool wet weather (at least in central MN and Twin Cities) has added to the slowed leaf development and produced environments favorable to anthracnose diseases. Ash, in particular, are showing symptoms of infection. Watch for leaf drop, which can involve green leaves as well as discolored leaves, and brown to black blotches on leaf blades and petioles. Ash anthracnose cannot be cured, but can be prevented through fungicide applications. Because anthracnose rarely affects the long-term health of the tree, prevention is usually not needed. This year, severe anthracnose may add to the stress caused by the winter injury and may thus lead to decline. It is too late for effective treatments this year. But those with struggling ash may want to consider preventative treatments next year. Talk to a forester or certified arborist about the need for and timing of preventative treatments.