Butternut canker, an apparently exotic disease of uncertain geographic origin, is central to the decline of the species. The causal organism is a fungus?-?Sirococcus clavigignenti-juglandacearum?-?and its most damaging effect is to cause girdling cankers, especially near the root flares where coalescence of numerous infection sites led to decline and death of host trees. Dale Bergdahl?-?now Professor Emeritus with the University of Vermont- has researched butternut decline for more than 35 years and continues to press on as he seeks some workable solution to this problem.