Norwich’s Forests Are Under Attack

Norwich’s deciduous forests are on the verge of dramatic change, thanks to a tiny invertebrate invader. Unfortunately, the changes – already well underway – will not be welcomed by any of us. As this transformation rapidly unfolds before our eyes, Norwich and countless other towns in eastern North America must confront, manage, and adapt to a new reality.

The winter 2024 discovery of emerald ash borer (EAB) in Norwich came as no surprise to the Norwich Conservation Commission (NCC). Since the 2018 arrival of this non-native beetle in Vermont – first documented in Orange County – it has rapidly spread to all of the state’s 14 counties outside the Northeast Kingdom. EAB (Agrilus planipennis) was first found in the U.S. in southeastern Michigan in 2002. Native to Asia, it is believed to have been introduced as early as the 1990s in imported wood packing material. EAB feeds exclusively on ash trees in the genus Fraxinus. Vermont’s three species of ash – white, black, and green – make up 5-7% of all hardwood trees in the state, with higher percentages in some areas, such as Windsor County. As of early 2024, this tiny green beetle has killed millions of ash trees in 36 states and five Canadian provinces, causing devastation not seen since Dutch Elm Disease and Chestnut Blight ravaged our streets and forests 50-100 years ago. This invasive insect will inevitably destroy most, if not all, ash trees in Norwich and beyond, posing serious human safety risks, threatening the ecological integrity of our forests, and diminishing a cherished cultural and aesthetic resource.

The ecology and impacts of EAB are well described in various online sources, including an informative fact sheet published by the Vermont Department of Forests, Parks, and Recreation. The half-inch long, bullet-shaped, metallic-green adult beetles lay eggs in the crevices of ash bark, where larvae tunnel into the cambium and feed on the phloem, which is the vascular tissue responsible for transporting nutrients throughout the plant. As larvae feed on this vascular tissue, the tree becomes less able to transport nutrients to the leaves in its canopy, killing the tree from the top down in a span of 2–5 years, depending on its size and health. Infested ash trees rapidly begin to dry out and lose their structural integrity; branch and trunk breakage in diseased ash trees is often sudden and unpredictable, posing a real hazard to people and property. Infestation typically expands rapidly at a rate of 1–2 miles per year. Learning to identify ash trees and the symptoms of EAB damage are vital first steps to understand and manage a local infestation.

The State of Vermont has taken EAB very seriously since it emerged on the radar of forest managers and ecologists over a decade ago. The Vermont Urban and Community Forestry Program has a dedicated web page on EAB Management, which highlights the many resources available to communities like Norwich that are striving to manage this damaging insect pest. A number of Vermont municipalities have adopted formal plans to prepare for and manage EAB infestations. Although the NCC conducted preliminary roadside counts of ash trees in 2018 and 2019, in anticipation of EAB’s arrival, our town does not yet have a management plan in place. The process of creating such a plan is now earnestly underway.

Three basic options exist for managing EAB infestations, and most Vermont communities have adopted action plans that combine all three. These include:

1. Stem inoculation of ash trees that are considered high-value, because of their cultural, aesthetic and/or historic importance to a community or an individual landowner.
2. Preemptive removal of healthy ash trees that, once infected, will pose an unacceptable risk to property, infrastructure, and/or public safety.
3. Allowing trees that are neither high-value nor a risk to public property and safety to become infected and die. This latter strategy typically applies to ash trees that are situated away from public spaces, residential homes, or commercial buildings.

Norwich has ash trees that qualify for each of these treatment options, and the NCC is undertaking a diligent effort to inventory and evaluate trees along our roadsides and in public spaces. Norwich’s density of roadside ash is among the state’s highest on record, averaging >125 trees per mile of town road.

Inaction on managing EAB impacts is not an option for Norwich – or any community with ash trees. The documented presence of this destructive pest throughout town underscores the urgent need to develop and implement an effective action plan. Town officials, including the tree warden and members of NCC, are working hard to craft such a plan. That plan, when completed this fall, will be adjusted as needed in response to the progression of Norwich’s EAB infestation and new knowledge that emerges. Proactive treatment or removal will be expensive, but reactive removal of infested ash trees and coping with the damage they cause will entail much higher costs.

EAB will affect every Norwich resident, as it proliferates and kills our ash trees. We must all learn about this invasive insect, monitor our own properties for evidence of infestation, educate our neighbors, not relocate infested wood when trees are cut, and start planting replacements. Only a concerted, coordinated management plan and town-wide effort will avert the worst disruption and expense that EAB is poised to inflict on Norwich.

To keep abreast of EAB planning in Norwich and/or to learn more about your own management options, please check our page on emerald ash borer, and contact us with questions. We have a huge community challenge on our hands, and we need all Norwich residents to participate in seeking solutions!