Emerald ash borer (Agrilus plannipennis Fairmaire) is a federally regulated pest and poses a tremendous threat towards natural forested areas and municipalities across North America and Canada. Emerald ash borer (EAB) is a highly destructive, non-native invasive beetle responsible for killing more than 100 million ash trees throughout the United States. Originally from Asia, the metallic wood-boring beetle was first discovered in Michigan in 2002, where it was presumably thought to be present for roughly 10 years or longer before being detected. Since then, EAB has now become established in 35 states across North America, including Colorado. In September 2013, EAB was positively identified in the City of Boulder, making it the first identification within the state of Colorado. Nearly three years later, in early June 2016, EAB was confirmed within the City of Longmont, and then detected a month later in the close proximity area of Gunbarrel. In August 2017, EAB was detected in the City of Lafayette, and in March 2018 EAB was detected in the Town of Lyons followed by its detection within the City of Superior in June 2018. In August 2019, EAB was confirmed in the City and County of Broomfield, making it the first appearance outside of the regulated quarantine. Approximately two weeks later, in early September 2019, EAB was identified in the City of Westminster (Adams County), and on September 24, 2019, EAB was detected in Larimer County just outside of Berthoud town limits.
It is suggested that EAB is the most destructive insect to hit North America. At first, when
populations are low, neglect damage from the beetle is noticed; however, EAB’s “fitness” (ability
to survive and reproduce) is substantially high allowing for populations to quickly increase in
number. Therefore, once established and populations become highly dense, healthy trees can
die within several years if untreated.
Though EAB can infest new areas naturally, the main method of EAB introduction is unwilling by humans. The transportation of infected firewood to other areas for use or sale, along with other ash material, is the number one factor contributing to new infestations. Once EAB is detected, federal agencies establish quarantine areas regulating the movement of hardwood materials within the infested area. Originally, a Federal and State quarantine was placed on Boulder County; however, since the presence of EAB has expanded past this regulated boundary, both the Federal and State quarantine have been lifted.
Out of the +6,000 street and public area trees in Berthoud, roughly 22% of trees are ash (Fraxinus spp.). Ash trees, though not native to Colorado, have been heavily planted throughout the state as street and shade trees due to their fast growth rate and high adaptability. The two most common species of ash planted in the Front Range are green ash (Fraxinus pennsylvanica) and white ash (Fraxinus americana). However, all species of ash in the genus Fraxinus are at significant risk of elimination from this devastating insect.
Since its discovery in 2002, research on chemical treatments has resulted in success. The most widely used treatment are micro injections to protect the tree, these injections can protect the tree for up to two years costing several hundred dollars per tree depending on its size. Chemical soil drenches around the base of the tree have also been somewhat effective as have bark sprays. Bees are thought not to be affected since they do not visit the pollen on ash trees, their pollen is wind distributed.
So where do we go from here? The Town of Berthoud and the Tree Advisory Committee have been proactively working since the discovery of EAB within the City of Boulder limits. Town Staff and Tree Advisory Committee Members attend state conferences and workshops regarding EAB management and control, and are remaining up-to-date with the latest recommendations and literature publications for chemical treatments. Town Staff has developed an Emerald Ash Borer Management and Response Plan intended to provide best management practices for Town of Berthoud Staff as well as residents within the Town to reference as needed. Town Staff and Tree Advisory Committee Members also plan to hold community workshops and make available printed material to educate the public regarding recommended treatment protocols, how to identify an ash tree, and most importantly, what EAB infestation symptoms to look for.