My green ash trees have been dropping leaves this spring. Why?
My green ash trees have been dropping leaves this spring. Why?
The leaf drop is probably due to anthracnose. Anthracnose is a common fungal disease of trees in Iowa. Anthracnose may occur on ash, sycamore, maple, oak, walnut, and other deciduous trees (see encyclopedia article Anthracnose on shade trees). Cool, rainy weather in spring favors anthracnose development. Symptoms of anthracnose vary with the tree species. On ash, brown or black blotches typically appear on the leaflets. Affected leaflets often become distorted (they tend to curl toward the blighted areas) and fall from the trees.
Fortunately, anthracnose does not cause serious harm to healthy, well established trees. The affected trees will continue to leaf out. Leaves that develop later in spring are usually not affected as weather conditions are less favorable for anthracnose development. There is no need to apply a fungicide to affected trees.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on . The information contained within may not be the most current and accurate depending on when it is accessed.