New Hampshire moves to keep ash borer invasion from spreading

By BILL CHAISSON
[email protected]
(This article was updated on July 25 with remarks from Vermont forester David Paganelli.)

SULLIVAN COUNTY — The first emerald ash borer (EAB) to be spotted in New Hampshire was found five years ago in Concord. The insect, originally from southeast Asia, arrived in Detroit in 2002; it had hitched a ride in some wooden packing crates made of tropical ash. Since then it has spread to 34 states and provinces. On its own this very tiny beetle — they are 1/3 of an inch long — only disperses a mile or two per year. It has spread around the continent in ash logs that have been transported as firewood.

Entomologist Kyle Lombard, the coordinator of the Forest Health Program for the New Hampshire Division of Forests and Lands, was upbeat about the state of the outbreak in the state. “It has spread more slowly in New Hampshire,” he said. “We got out in front of it here. They’ve always been behind it in other places. We’ve found the edge of it. We’ve had good outreach and tighter regulation and people are following the rules.”

Lombard said that in other parts of the country officials have reacted to a single outbreak by quarantining the entire state, which is difficult to enforce. In contrast, New Hampshire has managed the problem county by county. As a result thereare more tightly regulating smaller areas, and it has been contained to five counties — Merrimack, Belknap, Hillsborough, Rockingham, and Strafford — in the state.

The beetle has worked its way northward through New England. It reached Connecticut in July 2012, Massachusetts in September 2012, New Hampshire in April 2013, Vermont in February 2018, and Maine in May 2018. These infestations have occurred at widely scattered locations because they are the result of the interstate transport of firewood.

According to the New Hampshire Division of Forests and Lands, “In the past 10 years research has definitively shown firewood to be a major pathway for the long distance movement of forest pests across the United States. Here in New Hampshire the Division of Forests and Lands has conducted many surveys and research projects and found over 40 percent of the out-of-state campers were bringing firewood from home. Transporting firewood from California, New York, Florida and other distant locations was common. Out-of-state firewood the division has confiscated and studied has averaged 35 insects per stick of wood. Additionally, the breadth of species has been amazing. Species from the smallest flies to the largest longhorn beetles have been found in firewood.”

The traps that are hung from roadside trees to collect EABs are three-sided, a deep purple color and about two feet tall. There are at least two hanging in Unity. Sullivan County is outside of the quarantined area of New Hampshire, so the traps in this area are hung and monitored by the U.S. Department of Agriculture, specifically the Animal and Plant Health Inspection Service (APHIS). Lombard explained that APHIS monitors regions outside quarantined places “to make sure that any outbreak is known.” Although the outbreak nearest Sullivan County is in Warner, the EAB has been spreading in Vermont as well.

Lombard said that biocontrols have been released in infested areas of New Hampshire and they are working well. Fifteen years ago, he said, the USDA examined what controlled the EAB in Asia. They spent a decade doing research that made sure that three species of parasitic wasp would not affect other species in North America. One species parasitizes EAB eggs and two others attack the larvae. “It will take 10 to 20 years to get the parasite populations up to where they control they beetles,” Lombard said.

What is at stake? Lombard estimated that ash constituted 6 percent of the hardwood forest of New Hampshire. “That is millions and millions of trees,” he said. “They are a valuable part of the lumber industry and that is a billion-dollar industry.”

David Paganelli, the state forester for Orange County in Vermont, sent an email in response to Eagle Times inquiries. “I am aware that New Hampshire is introducing the parasitic wasps, but am unsure if there is a plan to do that in Vermont,” he wrote. “New Hampshire has a little bit of a jump on us since the emerald ash borer was found there some time before it was found here.”

Paganelli took a long view on the future of the Vermont ash population. “The general thinking now is that between introduced parasites, woodpecker predation and natural resistance (maybe 1 tree in 100), we may be able to, someday, have an ash component in our forests again,” he wrote. “We are told to expect near 100 percent mortality of large ash trees in the first wave, but then as natural predators establish, and the few surviving ash (that may have some resistance) regenerate, we may begin to see a resurgence.” 

Vermont is generally concerned about its timber industry in the near term. In a March 2018 video posted at the website of the state Agency of Agriculture, Food and Markets, forester Bill Sayre of The A. Johnson Co. in Bristol, Vt. said that the EAB was a threat to those who earn a living from forests. He said that while maple is the number one product for Vermont, ash is prominent because it is made into furniture, flooring, paneling, and cabinetry. He recalled the American chestnut blight of the early 20th century, which wiped out that species as a lumber producer.

Steve Sinclair, the director of forests for the Vermont Department of Forests, Parks, and Recreation said the EAB has been found in Orange, Washington, and Caledonia counties in the towns of Orange, Plainfield, Groton, and Barre. When Sinclair spoke in March he said that the state was continuing “delineating surveys.” State foresters drive down the road and look for “suspect trees,” inspect them for infestation, and log their location.

Sinclair also warned that the EAB could be devastating for urban tree populations as well. A June 27 report on Vermont Public Radio announced the arrival of EAB in Montpelier with the title “Say goodbye to your ash trees.” Geoff Beyer, the Montpelier tree warden said there are 600 ash trees in the rights of way of the city and 3,000 on private property within city limits.

The Eagle Times contacted the Claremont Department of Public Works — the city does not have a tree warden — to see if Claremont has a plan in place for ash tree removal, but department superintendent Scott Sweet was out of town.

Tim Fleury, a field specialist for the UNH Extension in Merrimack County, which is infested, posted a video to YouTube on June 9, 2017 that explains how to identify infested ash trees on your own property. “Usually we don’t notice it until the woodpeckers show it to us,” he said. “I call it zen and the art of detecting ash borers. Until the woodpeckers let us see it, we’re not going to find it.”

The birds strip the bark from the trunks in an effort to uncover the larvae, which live in the cambium layer. This layer carries most of the nutrients throughout the tree and also is a place for cell division, producing both bark and wood cells. The stripping process, Fleury said, is called “blonding” because it leaves a light colored patch of exposed cambium on the trunk. The blonding reveals “galleries” where the larvae have eaten their way through the cambium.

Adult EABs mate at the top of the tree and then the female climbs down through the branches, laying eggs has she goes. The tree is fully infested, said Fleury, by the time the insects are close enough to the ground to observe.

New Hampshire enacted an “exterior” firewood quarantine in 2011, two years before infestation, prohibiting importation of firewood from out of state. New York, Vermont, and Maine have similar bans. The regulations were recently updated — the comment period ended June 15 — to adopt a more specific definition of “firewood”; lower certified heat treatment standards used to exempt wood from regulation; and changes to eligibility for compliance agreements that allow wood importation.