Are Walnut and Ash Trees At Risk?

Are Walnut and Ash Trees At Risk?

I have been advised that a beetle has become a threat to walnut trees, is in the USA’s West, and could cross the Mississippi River soon. I was also advised that walnut grown west of the Mississippi River should not be brought (or shipped) to anywhere east of the Mississippi River to prevent the disease from spreading. Also, that a beetle has invaded North America from China. It is attacking Ash trees, and some foresters are saying that it will probably wipe them off the face of the continent. Is there truth to these stories, or are they just legends? – Bill Greaves

Rob Johnstone: Both of the stories you have talked about are true. The black walnut tree threat is in many Western states and, according to some unverified reports, has indeed crossed the Mississippi River to the east. The emerald ash borer is moving unchecked across the Eastern hardwood forests. Barring a successful chemical or biological treatment, it will certainly be the end of the ash tree population as we know it.

Tim Inman:¬†Harry Truman had it right when he said, “History is just one damned thing after another.” I live in southwest Iowa. For years, our walnuts (they grow like weeds here) have been on the second tier of favored woods at the sawmills. Seems as though we have some little grub that lives under the bark. It doesn’t kill the trees, but the woodpeckers that enjoy them, in their quest for lunch, do damage that lasts forever in the wood. Now we have another invader to finish off what the other ones couldn’t.

Although I did live through the Dutch elm Disease era, when every Iowa town went from forested streets to desert, I’m not totally pessimistic. That’s how Iowans speak positively, by the way; to say I’m mildly optimistic would be “too much.” Mixed forest stands, selective cutting, and NOT transporting wet wood or green logs would be just commonsense things we can do while the scientists work on the problem. Sawed, dry wood (lumber) can be safely moved about, so there will be American black walnut for us to use for many many more years. We now have disease-resistant American elms, so there is hope.

We have green ash here. We do not yet have emerald ash borer in Iowa (except for one tiny spot on an island in the Mississippi river in the northeast corner of the state). Our ash is not a long-lived tree anyway. We have many other borers and insects that enjoy damaging it. But there’s always something!

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