In the 29 years since a fungal disease known as butternut canker
was first observed in southwest Wisconsin, it has infected over
90 percent of butternut trees throughout their native range from
New Brunswick, Canada, to Georgia to Dale Bergdahl, recently
retired after 29 years as a University of Vermont forestry
professor, has been tracking more than 100 butternut trees here
in the University of Vermont’s Jericho Research Forest. Dr.
Bergdahl was the first to find the canker in Vermont, near Snake
Mountain, in the fall of 1983. Since then, it has killed half
the butternuts in the state. The fungus, Sirococcus
clavigignenti-juglandacearum, was described as a new species in
1979 and bears the earmarks of being recently introduced. But it
has never been found outside North America. Dutch elm disease
and chestnut blight, also caused by fungi, were notorious, and
much more conspicuous, because elms and chestnuts were ...