“Kiss Your Ash Good Bye”


That’s what the Massachusetts state forester told me – the emerald ash borer is on the loose in southern Berkshire County where my wife and I have our 130-acre woodlot and within the next couple of years this pest is expected to kill virtually all the native ashes, or roughly 5% of the forest trees, in this region. In fact, this mortality is expected to become general throughout Connecticut, too, and eventually throughout southern New England and beyond. And to my mind, it is a good argument for the creation of GMO plants.

Ash infested with borers (Daniel Herms, The Ohio State University, Bugwood.org)

This loss of trees to an introduced Asian pest is even more grievous in context. My region lost all its American chestnut trees (as much as 1/4th of the hardwood trees) to the ravages of an introduced Asian virus in the early part of the 20th century. More recently, it lost most of its hemlocks (an estimated 6% of the forest trees) to an introduced Asian insect pest. If the Asian Longhorn Beetle ever escapes from its limited urban outbreaks into the forest in general, 73% of the forest trees in southern New England would be at risk.

Asian ashes, chestnuts, and other trees which evolved alongside the Asian pests have a natural resistance. American scientists have tried to interbreed these Asian trees with their American relatives to transfer the resistance but given the long time it takes a tree to grow from seed to sexual maturity, progress has been painfully slow.  A 35-year effort by the American Chestnut Foundation to breed a resistant American chestnut, for example, has only begun to produce significant results in the last few years.

Genetic engineering offers a far more efficient way to insert genes for pest resistance into the DNA of American trees. This has already been accomplished with American chestnut trees and Dr. Paula M Pijut, a research plant physiologist with the U.S. Forest Service, has been working on something similar for several species of North American ash trees in her laboratory at Purdue University. Both of these projects have been accomplished in a time scale of years rather than decades. An additional advantage of genetic engineering is that it is possible to produce resistant trees that differ from their American ancestors by only a handful of genes rather than the compromise Asian-American hybrids produced by conventional breeding techniques.

I’m no fan of GMO food, but GMO trees seem to me a far better alternative than a biologically impoverished forest.

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My father was a compulsive tree planter, but it was my mother who taught me the finer points of gardening.

Her homeschooling was followed by two years in the New York Botanical Garden’s School of Professional Horticulture, and then ten years as horticulturist at an Olmsted Brothers designed estate on the Hudson River Palisades.

I’ve worked as a horticultural journalist for 35 years, contributing to publications ranging from Martha Stewart Living to the Journal of the Royal Horticultural Society and The New York Times.  My most recent book is Nature Into Art: The Gardens of Wave Hill, which is a tour of the lessons to be learned from that great public garden.  I’m currently focusing on my new podcast (at thomaschristophergardens.com) which features weekly interviews with leaders of environmentally-informed gardening.

My special enthusiasms include sustainable gardening, especially sustainable lawns;  heirloom chicken breeds; and recreating vintage New England hard ciders.


Contact Tom by email


  1. Yes. Like any technology, GMO is evil only in inappropriate applications. When unregulated and applied for the short-term profit of a particular company (I’m looking at you, Monsanto) it will not have our common interests at heart, let alone nature in general. Having introduced the pests, there are no natural and satisfactory responses, only best of several imperfect choices. GMO focused on resistance to an introduced pest sounds just right. It’s what nature would do, after all, given 1000 years of the current situation.

  2. Sorry those nasty little bastards have reached New England. Caused lots of damage in the Great Lakes states. Think they came into a Michigan port. I wonder, have any Western Hemisphere pests been accidentally sent east?

    • I know that the black squirrel (a grey squirrel mutant) in the UK and the raccoon in Northern Europe and Japan are introduced from North America. I imagine that both are at least a low-level pest.

      I haven’t read this yet, but I’ve bookmarked it:
      “Invasive species in Europe: ecology, status, and policy”

    • Actually, I just heard a lecture about how an American fungal disease is killing all the red pines in Japan. I think that because the Asian flora is bigger and more diverse, it tends to have more pests and we suffer more on this end.

  3. I dislike how people turn against GMO’s. It is a technology not a product. Like any technology it can be used for good and bad things. Too often I see people lumping all GMO products together with an air of hatred, leaving no room for situations like this were the technology could be used for very good things.

  4. Good morning from central Indiana, where all the mature ash trees are dead or dying. One thing I’ve noticed as they die, however, is that under that stress, they produce tons of seeds. So I encounter ash seedlings all over the place. Perhaps you should begin gathering seeds from prime specimens around your acreage and find a seedbank to store them for you. It’s not answer to the problem you face but it could contribute to the solution you propose.

  5. Here in Oregon we have been dealing with the pine bark beetle, which destroys Ponderosa pine trees. We had a devastating ice storm a few years back that basically served up a smorgasbord of vulnerable trees to the beetles. Now that many of the trees in our area have been removed and time has gone by, the surviving trees seem to be doing ok. Meanwhile, a fir beetle of some kind is supposedly moving in…..and we have a lot more fir trees in our forests than Pondies. So my question is, in the countries of origin for these beetles, what is their nemesis? Have these beetles wiped out those trees completely, or is there a cycle they go through, leaving just enough trees to replenish their food source for the next go-around?

  6. It’s hard to argue against GMO as an unnatural approach, when we’re expecting our forests to withstand unnatural threats. I fully agree with kermit in that any technology could put to use for good – or bad.

    Of pests going east, I know Australia is plagued with plenty of western species that have no place in their flora or fauna – some South American bug comes to mind, that suddenly devastated crops in Australia. At the time the solution they came up with was to introduce its natural enemy – a frog or toad. Only to find out that in Australia these frogs preferred other food and wreaked havoc all on their own – doing nothing to eliminate the first pest.

    So if GMO offers a better, more targeted solution, it seems much less risky IMO.

  7. As info
    Emerald ash borer is a phloem feeder and is therefore possibly good food for woodpeckers especially yellow-bellied sapsuckers. As soon as they are recognized as food, the problem may go away. GMO may not.

    People are the cause of this problem in the first place. Just quit the pesticides and make the environment a more hospitable place for the yellow bellied sapsuckers!! Easier, cheaper, better.

    • I don’t think that woodpeckers on their own can stop the ravages of Emerald Ash Borer. But maybe in combination with some other biological controls carefully selected from the borer’s insect predators in its homeland, the birds could moderate the damage. The Connecticut Agricultural Experiment Station found a tiny predacious beetle that feeds on woolly adelgids and is saving hemlocks in that state.

  8. I agree with Vicky about woodpeckers. There has been a study done that showed healthy populations of woodpeckers having a dramatic effect on EAB populations. As stated, woodpeckers may not save one tree but they could potentially save a forest. The birds themselves are fast to catch on- and more abundant food means more woodpeckers and the cycle sort of works. In areas where woodpeckers aren’t abundant but ash trees are (like in the middle of urban landscapes), I imagine woodpeckers won’t have as much of an effect. Maybe Ash won’t be a go-to urban landscape tree for a while?

    This makes me think of trees like the elm that are making a comeback. I have a butternut on my property that’s showing resistance to the canker that’s almost wiped the species out. There’s always reason for hope I think.

  9. Using genetic engineering to create trees resistant to the emerald ash borer is a very bad idea. One of the unintended consequences of breeding pest resistance into plants has been the creation of so-called superbugs. It only takes a few survivors to pass on resistance to whatever has been inserted to the ash’s genes to create a line of borers that will be even more difficult to eradicate.

  10. So many lovely trees that we have lost 🙁 Elms, Chestnuts now our Ashes! Interesting idea about GMO trees.. If it can help us stop losing out lovely trees, and who eats GMO trees, except birds, bugs etc.. Hmm

  11. Genetic engineering of trees to survive introduced pests may be, in a far more compact time scale, what Nature itself would have done to combat the pest, but that leaves high and dry the rest of the ecosystem which evolved with the original version of those trees. Do these potential trees produce pollen, or fruit, or seeds the wildlife can survive upon? Can the trees even be pollinated by the fauna, or will they themselves die out after being unable to produce viable seed (or will we be forced to then engineer GMO insects and birds to handle that task!)?

    Jeez, people. Stop thinking only of yourselves, please, and contemplate (instead/also) the larger picture in which you move.


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