Emerald Ash Borer. Image Credit: U.S. Department of Agriculture via CC
Since 2002, the Emerald Ash Borer has wreaked havoc on Ash trees all across the United States. According to landscape architect designer Nicholas Buesking, these pests have destroyed a significant amount of urban canopy, and the need for removal and replacement has placed economic pressures on many cities and towns.
While there have been many efforts to contain EABs, many of them have simply slowed but not stopped its spread. What’s always helped is the fact that the Emerald Ash Borer has seemed to affect only the Fraxinus species. Unfortunately, this has been proven no longer to be true. The Emerald Ash Borer has been confirmed in another host, the native White Fringetree (Chionanthus virginicus).
D-Shaped exit holes signifying the presence of mature Emerald Ash Borer. Image Credit: Daniel Herms, Ohio State University, via CC BY 3.0
Ecologist Dr. Don Cipollini, Jr. of Wright State University first discovered the infestation in 2015 in Dayton, Ohio. Of twenty White Fringetrees he surveyed in the Dayton area, four displayed signs of Emerald Ash Borer (EAB), which included exit holes and tree dieback. This was the first report of EAB developing fully in a non-Fraxinus host in North America.
Further research has shown that larvae that use the White Fringetree as a host can complete its maturation into adulthood; however, in one study, after forty days these larvae weighed approximately one third as much as those using a Green Ash as a host. Furthermore, galleries discovered in Fringetrees sometimes do not yield exit holes, which means the larvae failed to reach maturity. Such results suggest that, while the EAB can and does utilize the White Fringetree as a host, it is not an ideal host.
The implications of Emerald Ash Borer have been huge to the field of landscape architecture. Like Dutch Elm Disease, it has almost entirely eliminated a high-performing tree from use. The question remains: How serious are the ramifications of the EAB living in another host?
Experts warn that when the EAB has exhausted Ash trees as a host, there is a likelihood that the pest will turn with greater intensity to White Fringetrees. For now, plant with caution, especially within the current range of the Emerald Ash Borer.
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