P&PDL Picture of the Week for
May 17, 2004

Anthracnose of Shade Trees or Wind Injury:
Look Alike Symptoms Can Be Perplexing

Gail Ruhl, Senior Plant Disease Diagnostician, Interim P&PDL Director, Purdue University

The cool, wet weather of the past few weeks has been ideal for anthracnose of shade trees. Symptoms of this fungal disease are now showing up on ash, maple, oak, walnut and sycamore. Some trees are exhibiting extreme leaf blighting, and many sycamores will begin to look more dead than alive from extreme dieback of new shoots due to the canker phase of anthracnose and massive leaf drop.

Abiotic (noninfectious) factors such as environmental injury from excessive winds or frost damage that may have occurred earlier this spring may also cause similar foliar symptoms on various deciduous trees.

There is no need to spray anything on established trees for any of these problems. The most appropriate course of action at this time is to apply fertilizer to help trees push new growth and to water regularly during extended dry periods this summer. For additional information refer to BP-9, Anthracnose of Shade Trees located on the web at: http://www.agcom.purdue.edu/AgCom/Pubs/BP/BP_9_W.pdf (PDF 496K - Requires Adobe Acrobat to view and print). You may also download http://www.hort.purdue.edu/ext/HO-140.pdf for fertilization recommendations. Another article for reference is by Nancy Pataky in the Illinois Home, Yard, and Garden Pest Newsletter issue 04-4 called "Anthracnose or Wind Tatters or What?".

See previous article on Wind/Frost Damage

See previous article on Sycamore Anthracnose

See previous article on Anthracnose of Shade Trees

Click image to enlarge

Wind/frost damage

Sycamore anthracnose

Anthracnose on maple

Anthracnose on oak

Anthracnose on ash

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service