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

The cool, wet, weather experienced periodically this spring has been ideal for the development of anthracnose on shade trees.

 

Anthracnose is the common name for a type of leaf spot and canker disease caused by certain kinds of fungi. Anthracnose diseases affect many trees, but are particularly prevalent on ash, maple, sycamore, white oak, walnut and dogwood. Each species of tree is infected by a different species of fungus, thus the fungus does not spread from oak to maple or maple to ash or ash to sycamore. A different fungal species is also responsible for dogwood anthracnose.

 Symptoms will vary depending on the type of tree and the stage of plant development at the time of infection: leaf spots or blotches; twig dieback and wilting; and browning or death of emerging leaves are all possible. Premature leaf drop often occurs with anthracnose diseases, however, most of the trees infected with anthracnose usually show good resilience, and are not permanently damaged by this early season leaf blight.

 Sycamore anthracnose causes severe blighting of newly emerging leaves and shoots, and eventually causes twig and branch cankers which distort growth. Twig and branch cankers, shoot blight, and leaf blight are all symptoms of the fungus that causes sycamore anthracnose. Leaflet drop, as well as dead tissue along leaf veins or at the leaf edges is a symptom for ash anthracnose. Although defoliation may be so great that anthracnose-infected leaflets practically carpet the walks and lawns nearby, the tree is not dying, it simply puts out a new set of leaves. Anthracnose symptoms on maple and oak range from leaf spots to enlarged blighted dead areas along veins and sometimes to shoot blight.

 Abiotic (noninfectious) injury from environmental factors such as excessive winds or late frost/cold damage have also occurred this spring and may also cause foliar symptoms similar to anthracnose on various deciduous trees.

The most appropriate course of action for established trees suffering from severe effects of anthracnose is to rake and remove fallen leaves from beneath the tree; stimulate vigorous new growth with a balanced fertilizer after the leaves open and the spring rains have stopped; water regularly during extended dry periods this summer; avoid irrigation systems that wet leaves. 

​Leaf Diseases BP-143-W (pdf file)​​​

Gail Ruhl, Senior Plant Disease Diagnostician - Purdue Plant and Pest Diagnostic Laboratory

Purdue Master Gardener Program seeking new volunteers

Noblesville, IN (June 2, 2017) - Beginning August 14^th, the Purdue Master Gardener Program intern training will be offered for residents of Hamilton County and surrounding areas.  “The purpose of the Master Gardener Program is to help others grow.  The members of the Hamilton County program are a vibrant and active group that annually donate over 10,000 volunteer hours on approved projects throughout the county.” said Diane Turner, Master Gardener Coordinator with Purdue Extension. 

Training will be held from 5:30 p.m to 8:30 p.m. on Monday evenings (one Saturday workshop is included) at the Hamilton County 4-H Fairgrounds, Noblesville.  Participants will be exposed to a wide range of subjects including understanding soil and basics of plant science, diagnosis of plant problems, using pesticides safely, and growing a healthy vegetable, flower, landscape, and/or fruit plants. 

The Purdue Master Gardener Program is a volunteer training program that provides a learning framework for participants to increase their knowledge on a wide variety of horticultural subjects.  In turn, participants represent Purdue University as volunteers, sharing knowledge while providing leadership and service in educational gardening activities within their communities.

 Materials and expenses for the series of classes cost $150.00 per participant. This expense fee covers such items as reference notebooks, mailings, and name badges.  These materials all become part of the participants personal collection. 

While the class will be encouraged to create new educational outreach programs, there are already plenty of opportunities for which volunteers are needed.  Some of these projects include helping with the annual plant sale, staffing information booths at gardening events, teaching public education classes, speaking to local clubs and organizations, and hands-on demonstration gardens. 

The Purdue Master Gardener Program is an educational outreach of the Purdue Cooperative Extension Service.  If you'd like an application or have questions about the Purdue Master Gardener Program, please contact Purdue Extension Hamilton County at (317) 776-0854.  For more information about Purdue Extension in Hamilton County, visit www.extension.purdue.edu/hamilton.