John Guyon
US Forest Service
Plant Pathologist
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Comments Submitted (12/05/2006):
I just got a copy of "Ecology, Biodiversity, Management, and Restoration of Aspen in the Sierra Nevada". Congratulation on getting this publication out, I'm sure it will help land managers in this area.
I couldn't help but notice that you made mention of Agrilus planipennis in
the publication. Unfortunately, that's emerald ash borer, and unless EAB
has made a huge jump from the Midwest to the Sierra Nevada (and from ash to
aspen), I don't think that was the critter you were looking for. In my
experience, the two main borers found on aspen are poplar borer (Saperda
calcarata) and bronze poplar borer (Agrilus liragus).
Also, you mention Armillaria root disease, but again I think there is a
problem. In my experience, Armillaria root disease is capable of infecting
aspen, usually when in close proximity to infected conifers, but I've never
seen it kill all the roots of a clone in a root disease center. Also,
Cryptosphaeria canker can kill small stems, but usually only forms narrow
cankers on larger trees. The disease in Figure 3-6 looks like Cytospora
chrysosperma, which can girdle larger trees when they are under
environmental stress. Additionally, Cytospora canker is the most common
canker disease on aspen, and Crytosphaeria canker rot is actually pretty
rare, found on only about 2% of trees in Colorado, and less and 1% in Utah
and Nevada.
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