Cool and wet weather conditions in the spring are favorable for anthracnose fungi. Symptoms of ash anthracnose are beginning to appear. Infected leaflets often fall to the ground prematurely. A close look at the leaflets will reveal brown to black blotches. These spots commonly start at the margin and develop to the midvein. The leaflets tend to curl around the affected areas, causing a distorted appearance.
Images of ash anthracnose symptoms can be found on the Plant Disease Clinic website :
Anthracnose rarely causes significant damage to established shade trees, so control practices are generally not needed. Cultural practices that will help reduce leaf disease problems include raking and removing fallen leaves, removing any dead branches, and proper tree spacing to promote good air circulation. Protectant fungicide use is seldom justified.
Additional information on anthracnose can be found in Pm-1289, "Anthracnose of Shade Trees". This bulletin is available from your local Extension office or from the Iowa State University Extension Distribution Center, 515-294-5247.
This article originally appeared in the May 17, 2002 issue, p. 63.