Dutch Elm Disease Survivors
Native species of North American elms vary in their susceptibility to Dutch Elm Disease, even within species. American elm (Ulmus americana L.) is generally highly susceptible. Winged elm (U. alata Michx.), September elm (U. serotina Sarg.), slippery elm (U. rubra Muhl.), rock elm (U. thomasii Sarg.), and cedar elm (U. crassifolia Nutt.) range from susceptible to somewhat resistant. No native elms are immune to DED, but some individuals or cultivars have a higher tolerance (and thus may recover from or survive with infection) or resistance to DED. Many European and Asiatic elms are less susceptible than American elm.
In addition to genetic factors present in some cultivars and species, physical factors affect tree susceptibility. These factors include time of year, climatic conditions (such as drought) and vitality of the tree. Water conducting elements are most susceptible to infection as they are being produced in the spring, thus elms are most susceptible to infection after earliest leafing out to midsummer. Trees are less susceptible under drought conditions. Vigorously growing trees are generally more susceptible than slower growing trees.
From contributor A:
I have no scientific data but here in upstate NY on my 100 acres there have always been 50 to 60 elm trees that grow to about 10-12 inches in diameter before they die off. Seems like there are always a few dying and always a few growing.
From contributor B:
Here in NH we continuously get new elm saplings that grow to 8-10" before they die. But in northern NH and VT you will see a few scattered big elms (36" or more) that survive and look quite healthy.
From contributor C:
I sawed a large dead elm log for a neighbor (36" small end) three years ago and the boards looked good. The log had a lot of taper and I had to modify it with my chain saw. The owner had the butt log which was about 40" at the small end and I declined to saw it. It sat in his yard for a couple of years and disappeared but I don't know what he did with it. I remember many, many elms when I was young.
From contributor D:
In what way is elm making a comeback? Elm seems to have properties that make it not so easy to machine. On the other hand elm is very nice for its bending properties as well as being split and hewn. I had what I believe to be a Chinese elm on the mill, very pretty QS.
From contributor C:
I am a retired forester and saw a few elms in sales of timber that I conducted. I would leave them for posterity if they looked vigorous. Even if I marked them, the buyers would sometimes leave them unharvested. As for reproduction, I also observed small elm in a few areas, but none over 6 to 8 inches with a lot of dead elm mixed in. I have been monitoring several elms that I have seen in my travels, either in old pastures or roadside. A few have died already, but the largest in a clump of brush in an old pasture is 52 inches DBH and still kicking as of last summer.
From the original questioner:
I guess we can conclude there is no comeback then. Just wishful thinking on my part. Dr. Gene, thanks for that summary on Dutch Elm Disease.
From contributor E:
I know of a number of slippery red elms in my area that are doing fine, and I have just recently checked on some of them. We have some smaller ones that seem to be surviving and maturing, but I find very few other elm species. When I cut wood for any reason, I will never cut an elm unless it is damaged or clearly diseased. I wish there was more of them as they are very good looking trees.
Dr. Gene, perhaps you might have some knowlege. Is there any way that the tide of Dutch Elm Disease can be turned, or any way the trees can develop a resistance? I believe I have heard that all elms of any given species are basically identical genetically, which is why they are so susceptible. Is this the case?
From Professor Gene Wengert, technical advisor:
I am old enough to remember the beautiful elm city trees. I do not know much about Dutch Elm Disease. That is why I quoted the US Forest Service above.
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