Female emerald ash borer (Agrillus planipennis). Photo courtesy USDA Forest Service.

Emerald ash borer (EAB) is a non-native, invasive insect that has killed hundreds of millions of ash trees since its accidental introduction into the United States in about 1995.  Beginning in the Detroit, MI area, this insect has travelled across several U.S. states and Canadian provinces, and was first detected in New Jersey in 2014.  The mortality rate for ash trees since then is estimated to fall between 95 and over 99%.

EAB’s invasion of New Jersey from the west and the north. Original imagery courtesy of ESRI and the USDA Forest Service, edited by NJDSAF. Data provided by USDA Forest Service.

On top of bringing the terrible loss of services that ash trees provide our communities, the EAB threatens public safety.  Ash trees are known to become abnormally brittle shortly after their death, which can take up to 3 years after infestation to become noticeable.  When a chainsaw sends vibrations up an infested tree, it is not uncommon for limbs and branches to shatter and fall, endangering the cutter.  Using proper techniques to fell a dead ash tree safely costs 2-3 times as much as preemptively removing it.  The risk to the public and arborists is real, and the costs of inaction are mounting daily.

EAB-killed ash trees in Ann Arbor, MI. The whitish color on the trunk is “flecking” caused by woodpeckers. Photo courtesy of Steven Katovitch, USDA Forest Service, bugwood.org.

Given the insect’s rapid colonization of New Jersey, and the time lag in detection, it is believed that EAB will be present in every county in 2018.  The current understanding of this tree killer is that we should expect all untreated ash trees to die within 5 years.  The cost of treating individual ash trees with pesticide can be several hundred dollars per tree (depending on size), and treatment must be conducted at least once every two years.  Given that cost, a standard recommendation throughout the state is to treat only large, healthy, structurally-sound ash trees that the owner is willing to pay to retain.  Doing nothing with an ash tree in an area that people frequent is not an option.

Urban & community foresters view the landscape in which your town exists as a spectrum of different types of forests.  From the trees that line our downtown areas, to the riversides, parklands, and backyards in our communities, to rural woodlands, our forests are important.  These dynamic, disturbance-dependent ecosystems can adapt to loss of individual trees.  So too can wildlife in community forest settings.  Nonetheless, the decision to take down any individual tree is not taken lightly, but is done only after careful review.

EAB-killed trees. Photo courtesy PA DNCR Bureau of Forestry.

Foresters, arborists, and shade tree commissioners are extremely concerned about the future of our community landscapes — not just the here and now.  In anticipation of EAB’s arrival, planting of ash trees had stopped, and recommendations for future tree planting continue to be focused on the right tree for the right place in the right way.  “The right tree” needs to be resistant to not only EAB, but also to other non-native and native pests and diseases as well as other hazards of an urban/suburban setting.  For citizens who wish to do something to help, we urge you to contact your local government and community organizations and let them know that you support replanting trees in your community.

For specific information about what your municipality is doing to respond to EAB, click below:

The following agencies and organizations have been invited to partner with the NJ Division of the Allegheny SAF in this public outreach and education effort.  Click below to learn more: