Saving the Ash Tree

Emerald Ash Borer" (CC BY-NC 2.0) by Macroscopic Solutions

It’s been argued there was no more important kind of tree in the eastern half of North America than the American Chestnut. The “Chestnuts roasting on an open fire” at Christmas were American Chestnuts. The village blacksmith sat under an American chestnut. One of North America’s first “modern day” species to go extinct, the passenger pigeon, relied on American Chestnuts for food as did other wildlife.

Now they are all but gone; the victim of a blight that immigrated to North America from abroad. There are a few still alive and an effort to save the last remaining few, hybridize them and backcross them to come up with a blight resistant, modernized version to repopulate the landscape with these beautiful and important trees. It won’t happen in our lifetimes.

Now, a different invasive species is winning (has won, some say) another tree war here in the central part of the U.S.A. and Canada. The emerald ash borer, a native of Asia was first found in southern Michigan in 2002.

The war was on, but relentlessly, the insect spread far and wide and is now endemic in over 30 states and provinces – basically where ever ash trees are found. The sad part is an infested tree, like the chestnut tree with the blight, is doomed. Borer infestations have killed almost all mature ash trees in the northern two-thirds of Indiana and Illinois. The invasion is advancing south. Without intervention, all ash trees in these states will likely die.

Efforts to contain the spread were made, but basically, the war is over. Wild ash trees will not be a part of America’s woodlands soon. Not all are dead now, but soon.

It’s possible to treat individual trees with chemical insecticides to ward off ash borers and even save or prolong the life of the tree. Some homeowners are doing just that, but it’s expensive and, at least for the near future, treatment is something that will need to be done on an on-going basis.

In the worst case scenario, ash trees will go extinct in North America. Seeds from now-alive ash trees can be stored and planted, but just how long they will remain viable is up for conjecture.

That’s why the Indiana DNR is taking steps now to make sure at least some ash trees in Indiana will survive the invasive emerald ash borer invasion. The agency plans to use chemical treatments to protect large specimens of ash trees in areas unaffected so far by the borers and will attempt to keep them from becoming victimized when the EAB war comes to them. The project includes trees in Turkey Run State Park and in several nature preserves.

Candidate trees were identified and tagged by staff from DNR Nature Preserves. Treatments will take place this spring and will include at least a few specimens of all ash species found in Indiana: white, black, blue, green and pumpkin ash.

Saving ashes from the borers will require commitment. They must be treated every two to three years. Once the EAB “killing wave” passes through, and most ash trees are gone, treatments may not need to be as frequent.

The DNR is hoping to save these important trees for everyone to enjoy. But there are several other and important reasons for saving at least some large ash trees. One of the most important is that female ash trees that are saved can serve as a seed source for EAB-resistant ash breeding efforts. There’s hope, breeding and hybridizing efforts, combined with potential developments through chemical or genetic breakthroughs in the future may produce resistant trees or the ability to keep borer populations in check. Eventually, this could lead to the re-establishment of ash trees throughout its range.

For some, the chance to see these large trees in years to come is reason enough.
The big ash trees that one sees when walking the trails at Turkey Run State Park and Big Walnut Nature Preserve are inspiring. They could become future living monuments.


  1. Purdue is working on 3 EAB specific predators so there may be some hope for the future. We have treated some trees on our place to have a seed source for the future and keeping our fingers crossed

  2. I’ve got baby ash trees literally coming out of my ears here in Brazil, IN. I think they came from bags of cheap brown mulch from Wal-Mart. Everywhere I put the mulch has baby ash trees (variety unknown) sprouting up in it. I’ve not pulled any of them, I’ve moved a few, but in a few years, these saplings are going to become a problem. Most of the big ash here are dead or close to it, so that’s why I don’t bother the saplings. If anyone knows anyone in DNR that wants to come and dig these things up and take them, I’m all for it!

  3. Join the fight against emerald ash borers by donating to the Indiana Parks Alliance’s Save Our Ash Trees (SOAT) campaign. 100 percent of every donation goes toward treating ash trees in state parks or state nature preserves. Nearly $29,000 has been raised so far but much more is needed. Go to for more information on the ash tree campaign and how you can support it with an online donation. The Indiana Parks Alliance is a charitable organization whose mission is to support and advocate for Indiana State Parks and Nature Preserves.


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