The Purdue Plant and Pest Diagnostic Laboratory

What's Hot on May 27, 2005
at the P&PDL!

Ash Anthracnose

Gail Ruhl, Plant Disease Diagnostician, Purdue University

Last week the question was “Why is my sycamore tree losing leaves?” Now the hot topic is “What is wrong with my ash tree?”  The answer to both questions is “Your tree is infected with a fungal disease called anthracnose.”

Ash anthracnose is caused by a species of the fungus Discula.  Leaf blight due to infection by this fungus can be seen in neighborhoods and landscapes alike.  Leaflet drop may be so great that anthracnose-infected leaflets practically carpet the walks and lawns nearby.  Dead tissue appears along leaf veins or at the leaf edges because infections occur where moisture lingers longest as dew or droplets on those parts of the leaf. Although defoliation may be extensive, the tree is not dying.  However, since a new set of leaves will need to be produced, at a cost of carbohydrate reserves, invigoration with root zone fertilization might be beneficial.

For more information refer to Anthracnose of Shade Trees - BP-9-W (PDF 493K) 

Images courtesy of Mark Chu, Plant & Pest Diagnostic Lab

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ash anthracnose

ash anthracnose

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service