Fraxinus latifolia

Fraxinus latifolia occurs from California north to British Columbia. While the species may be secure presently, it is highly threatened by the arrival of the Emerald Ash Borer, which is steadily making its way across North America. This nonnative pest has caused serious declines in the eastern ashes

Fraxinus latifolia occurs from California north to British Columbia.

A serious potential threat to this species is mortality and reduced regeneration associated with the Emerald Ash Borer, a phloem-feeding beetle native to Asia. The invasive Emerald Ash Borer (EAB), Agrilus planipennis Fairmaire, 1888, was introduced in Detroit, Michigan from Asia in the 1990s (Haack et al. 2002) and has since caused rangewide declines in eastern ash populations. it is spreading across North America making it as far as Colorado, and while not yet on the west coast, there is a strong possibility it will make it there (Emerald Ash Borer Information Network 2020). The beetles feed on the leaves and lay their eggs in crevices of the bark. Larvae feed in the vascular structures during the summer, creating serpentine shaped galleries. They typically prepupae overwinter in the trees with pupation lasting from April-May, when adults emerge. Emerald Ash borers cause significant damage to the foliage of the tree and the vascular tissues. The tree will typically die within two years of the infestation (Poland and McCullough 2006). Within six years of an infestation, up to 99% mortality was observed in eastern ash species (Knight et al. 2013, Klooster et al. 2014, McCullough et al. 2008, Steiner et al. 2019). While an infested tree are observed to push out root sprouts for one to two years, it usually dies (Klooster et al. 2014). The mass mortality of reproductively mature plants that would replenish the seed bank and the relatively short persistence in the seed bank (2-3(7) years) (Klooster et al. 2014), causes concern about the species ability to regenerate post-infestation.