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Sunday - September 25, 2011

From: Washington, PA
Region: Mid-Atlantic
Topic: Non-Natives, Diseases and Disorders, Pests, Trees
Title: Swarming insects on non-native willow in Washington PA
Answered by: Barbara Medford


I have had a very large, beautiful pillow willow bush/tree growing next to our garage for about 8 years. Last year at the end of August, it began to attract white-faced hornets and yellow jackets by the hundreds, which I wrote off as a passing swarm once the weather cooled. However, the same thing happened again this year and I feel, with small children and dogs, we have a problem that needs addressed for safety reasons. Right now, there are thousands of both white and yellow "stingers" focused on the base of the tree. I cannot get very close to the tree, but have noticed a layer of small, black, rice-sized bugs covering sections of the far reaching branches. The trunk of the tree also looks like it has been splashed with black stain. Is the tree too far gone? Should I rip it out and start again by rooting some clippings or will the problem transfer? It hangs out over a grape trellis so I have hesitated to use poison.


Okay, we give up. Our research did not turn up any plant called a "pillow willow." We can pass on to you, if you wish, the websites where you can order a pillow with a picture of a willow on it. So, with your permission, we will address the problem of the generic willow tree.

The thing is, we're not crazy about willows, regardless of their name. There are members of the Salix (willow) family native to North America. They are not, generally speaking, considered landscape plants, but mostly occupy wetlands in their native areas. From the webpage on Salix bebbiana (Bebb willow), which is native to North American, here are the Conditions Comments:

"Short-lived and fast-growing. Susceptible to insect, disease, and wind damage."

This basically sums it up for willows, wherever they come from. Here are links to some previous answers on this subject, so we don't repeat ourselves:

From Cumbola, PA

Disease in non-native willow

We searched the Internet on "hornets and yellow jackets in willows" and found this article A Yellow Jacket Infestation in Willow Trees. Then, we looked at "Pests and Diseases of Willow Trees." From one of our favorite sources for horticulture information, North Dakota State University, we found Questions on Willows.

Now to cut to the chase. We think the tree needs to go. Obviously, you need to wait until the stingers have gone away for the winter, and even then, it would probably be better to have a professional arborist remove it and as much of the roots as possible. Then, during the winter, go to our Native Plant Database, click on Pennsylvania, and search on "tree" under General Appearance. You can also, in the same Combination Search, specify the amount of light the growing space has, how moist the soil, even desired height of the tree. We don't recommend taking cuttings to replace it, but to find a better-adapted healthy tree, native to your area-one that has a long lifespan ahead of it, and is less likely to develop diseases that will cause the sort of problem you are having now. Be happy with a willow pillow and forget the pillow willow-you'll be better off in the long run.


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