Reports of anthracnose on ash have been received from a number of counties across the state. The presence of this common springtime disease is usually noted when complaints are received that leaves are falling from ash trees.
A close look at the leaflets will reveal brownish-black blotches. These brown areas usually begin at the outer margin and develop inward to the midvein. Blotches may also occur on the tips of the leaflets. Distortion of the leaflet often occurs because the tissue tends to grow around the diseased areas. Images of ash anthracnose can be found under the disease of the week on the Plant Disease Clinic web page .
Damage from ash anthracnose is usually minor. Trees recover by producing new leaves. Protectant fungicide use is seldom justified. More information on anthracnose can be found in Pm-1280 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 25, 2001 issue, p. 61.