I'm almost certain that's not Chinese elm (Ulmus parvifolia) -- the trunk bark isn't "right". Need to see close-ups of leaves/twigs for a reasonable chance to ID it.

Well, looks like U rubra can be multiplied on U americana stocks, so perhaps the reverse will apply. I'll try it anyway and report back. The old tree blew down in January, but the scions still look pretty good.

Beng: Sadly, as previous posters have indicated, there is NO preventative or treatment for EY. There may be some pesticides available to control the vector (white banded elm leaf hopper?) but as the tree matures, I would think that would become increasingly prohibitive. D.C. elms and they are planting quuite a number of them, could be in jeapardy since EY is supposed to be spreading in that direction. The legacy elms at Penn State are about to be subjected to an onslaught, as well. Alden Townsend, who conducted the elm innoculation studies for the National Arboretum, posted a disclaimer on the web shortly after the release of Valley Forge and New Harmony stating that all american elm selections involved in his study did show susceptibility to EY in the lab. I would be curious to see if in fact Princeton did show resistance, although I would probably not plant in area where EY was known to exist. I don't believe EY as as widespread and systemic as ded and tends to be spotty. I hope this isn't a major outbreak.

Other bark beetles utilize already dead trees also. To help ID, it depends on which direction producing mother etches line out where offspring exit. I think that's one difference between native beetle and European Elm bark beetle. DED Disease is supposed to be able to survive several years living in infected roots. Since neighboring healthy elms are vulnerable for several years after diseased elm cut down. But I never heard of newly planted elm succumbing to root contained DED, probably because no one plants another vulnerable elm species. But DED is not like Verticillium wilt that can sit dormant for ten or more years in soil. Now Ash killed off from EAB have no facts in common with diseased elms. Except for that EAB is also a phloem bark beetle, but only attacks live trees. As breeding elm bark beetles utilize dead trees, which continue to be dangerous until bark sluffs off within two years. EAB does not infect or disease trees like DED, So as long as Ash wood is chipped under one inch of size, one can use as mulch.