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

New Video: Tree Pruning Essentials

Pruning has been called "one of the best, worst maintenance practices" performed on trees. The process creates wounds, which have a major impact on plant processes. Improper cutting on a tree causes severe damage or even death.  Click below to see the full video with tips on proper tree care with Lindsey Purcell, Purdue Specialist in Urban Forestry.

We Need Your Help Scouting for Asian Long Horned Beetle

Indiana residents are being urged to spend a few minutes checking trees in their yards and neighborhoods for signs of the Asian longhorned beetle (ALB), an invasive and potentially highly destructive pest.

Purdue University entomologist Clifford Sadof said early detection is the best way to contain the pest and minimize the risk to healthy trees.  "For ALB, the only tool we have is to eradicate the hosts," Sadof said. "No one wants to see apparently healthy trees cut down but the reality is that once the ALB is there, those trees are already dead."

Trees at risk of Asian longhorned beetle infestation include maple, birch, elm, willow, ash and poplar.  Identifying ALB early means fewer trees would have to be removed, he said.

"The sooner we find it, the smaller the area that could be affected," Sadof said. "The best way to protect our trees is by looking at them and reporting any suspicious signs. It takes just a few minutes to look around and it could save a lot of trees."

The Asian longhorned beetle originated in Asia and has no natural enemies in the Midwest. Infestations have been reported in Chicago and Cincinnati, putting Indiana squarely in the at-risk zone, Sadof said. He cautioned that the potential damage caused by Asian longhorned beetles is even greater than the risk posed by the emerald ash borer.

"That's because the Asian longhorned beetle can affect a greater variety and greater number of trees," Sadof said.

The Asian longhorned beetle is easy to recognize, Sadof said. Distinctive markings include:
* A shiny black body about 1-1 1/2 inches long with white spots.
* Long antennae with black and white bands.
* Six legs with bluish feet.

Signs of Asian longhorned beetle infestation are:
* Round exit holes, the size of a dime or smaller, in tree trunks and branches.
* Round or oval scars in the bark.
* Sawdust-like material on the ground near the tree or in branches.
* Dead branches or limbs falling from an otherwise healthy looking tree.

Residents who detect any of these signs should contact the Indiana Department of Natural Resources toll-free hotline, 1-866-663-9684 (1-886-NO EXOTIC). They can also download the Purdue Tree Doctor app for their mobile devices.

"The app provides photos that homeowners and professionals can use to identify both the Asian longhorned beetle and emerald ash borer," Sadof said.

Writer: Darrin Pack
Source: Clifford Sadof

Agricultural Communications: Keith Robinson 

Purdue Extension - Top 5 Tips for Tree Selection and Planting

Purdue Extension - Top 5 Tips for Tree Selection and Planting: Spring is a prime time for improving your property with new trees. They provide many benefits which everyone can share. Wise planning is essential to ensure the new trees meet your design needs and functional solutions as well. Follow these tips to get your tree started right and make it a long-lasting sustainable planting.

Purdue University Offers Four Plant Doctor Apps for Plant Problem Diagnosis

I would like to encourage you to take a look at the Purdue Plant Doctor suite of smart phone apps. These handy tools will help you diagnose and find recommendations to manage the most common insect, disease and environmental problems on the most common trees, annuals, perennials, and tomatoes in home gardens. The apps are a pocket encyclopedia that uses over 2,000 photos to identify and fix more than 200 problems on over 200 kinds of plants. 

Screenshots from Tree Doctor App

Imagine you are in your home garden and you notice a problem on the leaves of with your favorite shade tree. These apps will help you diagnose plant problems with an app in three easy steps. First identify the kind of plant that has the problem. So, for example, if you are using the Purdue Tree Doctor, choose the kind of tree (eg. oak, maple, or pine) to narrow your search. Second, you choose the part of the plant that looks bad (leaves, flowers, branches, trunk or roots) to narrow your search even further. Third, you match the problem on the plant with our photos by swiping through our collection of high resolution photos. To save you time, the app arranges the photos for each of the plants so that the most common problems show up first! You can confirm your diagnosis by reading details linked to the photo.

If you already know the problem you have, just skip the diagnostic process and look it up from a list. Then you can get detailed information about the damage the problem can cause, its life cycle and how to control it with some combination of cultural practices and, if needed, a pesticide or fungicide.

You may purchase all of the above mentioned apps by clicking on this link to buy from the iTunes or Android store.

Excerpts taken from Turftips Article by Cliff Sadof, Department of Entomology and Janna Beckerman, Department of Plant Pathology Purdue University