I'm going to reread the article again prior to taking the test for it, but in the first time through, here's the paragraph that took care of my curiosity about what we experience locally in Oregon with western hemlock...
Quote:
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The two Japanese and two western North American hemlock species are much more resistant to HWA than are their eastern North American counterparts. Of these four resistant species, the western hemlock (Tsuga heterophylla) is most similar to eastern hemlock in appearance, growth, form, and utility. Although adelgids do infest these resistant species, they seldom reach densities high enough to cause injury. Therefore, planting resistant Japanese and western hemlocks should reduce the impact of the adelgid in the ornamental landscape. However, the long-term success of these exotic hemlocks in the forests of eastern North America has not been evaluated.
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We had 3 western hemlocks ourselves, at our last home in Beaverton, Oregon, and they would get a few hundred or so of the white wooly spots on each tree, but fairly inconspicuous. Over 5 years, it was mild enough to ingore.
I suppose we should be glad that we don't need to arrange a battlefield with these here.