Anthracnose is a common springtime disease of ash, especially when we have wet weather. Diseased leaves show brown to black spots, usually developing from the margin inward. Leaf tissue often appears distorted as it sometimes curls or bends towards these leaf spots. People become aware of anthracnose on ash when infected leaves begin to fall in the spring. Although significant defoliation may occur, trees usually recover by producing new leaves. Fungicide sprays are generally not warranted.
Further information on anthracnose and photos of the disease symptoms can be found in Pm-1280 "Anthracnose of Shade Trees". This bulletin can be obtained from county Extension offices or from Extension Publications Distribution, Iowa State University, Ames, IA 50011.
This article originally appeared in the May 25, 1994 issue, p. 79.