May 23, 2007

Plant Disease Clinic Update - May 23, 2007

Samples with the following problems have been seen in the Clinic recently:

Anthracnose of ash

Canker on dogwood

Cedar-quince rust on juniper

Ash anthracnose

Why do my ash tree leaves look so awful this spring? Some of the new leaves and shoots are falling off, some are misshapen, and the older leaves have large black or tan regions. The Plant Disease Clinic has been getting these questions lately because the cool wet conditions in Iowa this spring have been very good for a fungus that causes anthracnose on ash. Anthracnose is just a big word for a number of diseases on trees and shrubs that result in blotchy black or brown lesions on leaves, deformation of leaves around the lesions, and complete defoliation in severe cases.