There are an estimated 8 billion ash trees in the United States[7] – the majority being white ash trees and green ash trees.[8][9][10][11] White ash trees are threatened by the spread of the invasive emerald ash borer (Agrilus planipennis), detected in Detroit, Michigan in 2002 and now found in eastern Canada and the majority of U.S. states, whose larvae kill ash trees.[1]
^Griffith, Randy Scott (1991). "Fraxinus americana". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 9 May 2018.
^Gucker, Corey L. (2005). "Fraxinus pennsylvanica". Fire Effects Information System (FEIS). US Department of Agriculture (USDA), Forest Service (USFS), Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 9 May 2018.