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Forest Service moves American elm tree a big step closer to landscape restoration

Photo of Photo (1) USDA employee inoculating an American elm tree with the Dutch elm disease fungal pathogens. 
 
Photo (2) Healthy American elm tree (left) and a tree that has succumb to DED (right). Photo (1) USDA employee inoculating an American elm tree with the Dutch elm disease fungal pathogens. Photo (2) Healthy American elm tree (left) and a tree that has succumb to DED (right). Snapshot : Over the past several decades, mature American elm trees have virtually disappeared from city streets and eastern forests as a result of Dutch elm disease. Forest Service scientists are on the cusp of developing sufficient genotypes to successfully restore new selections of American elm back to the landscape. Dutch elm disease inoculation trials initiated in Ohio in June 2016 yielded American elm cultivars that exhibit low levels of Dutch elm disease-induced decline one year later.

Principal Investigators(s) :
Slavicek, JimFlower, Charles E.
Pinchot, Leila 
Research Location : Delaware
Research Station : Northern Research Station (NRS)
Year : 2017
Highlight ID : 1265

Summary

Prior to the outbreak of Dutch elm disease (DED) fungal pathogens, American elm trees were widely dispersed across the eastern United States, thriving in a variety of different forest habitats. Over the last several decades, considerable progress has been made cultivating new genotypes of American elm trees that are tolerant to DED. Yet, from an operational standpoint the existing DED-tolerant cultivars lack the genetic diversity necessary for large-scale landscape restoration and are not regionally adapted. In June 2016, Forest Service scientists inoculated more than 850 American elm trees with DED to assess tolerance levels. The American elm material was derived from crosses between DED-tolerant individuals as well as material from large survivor trees. DED-induced canopy decline was assessed at eight weeks and one year after inoculation. At one year post-inoculation, 18 selections have exhibited tolerance (less than 20 percent DED symptoms) to the disease. These varieties will continue to be assessed for tolerance and will be incorporated into restoration plantings across the urban to rural gradient.