Emerald ash borer proving a potent pest for N.H., Maine forestry officials

The emerald ash borer: not a pretty picture for local forests. (USDA photo)

A destructive invasive pest that poses a dangerous threat to regional firewood supplies has made such inroads in New Hampshire and Maine that New Hampshire forestry and agriculture officials are now considering whether it's time to change the strategy from containment to control.

Traps in Lebanon, and Acton, Maine, were found to have the emerald ash borer earlier this week. It has already been discovered in much of Strafford County including New Durham, Farmington and Strafford.

Current migrations patterns suggest it will be in Rochester and Barrington in three-to-five years.

The EAB, native to Asia, is a highly destructive pest of forest and ornamental ash trees, able to kill a mature tree within just a couple of years of infestation. Since its initial detection in southeastern Michigan near Detroit in the summer of 2002 it has spread rapidly. As of August, it has been found in 35 states and four Canadian provinces.

Its principal destructiveness comes from its decimation of ash trees, coveted for their clean-burning properties and ability to be burn right off the stump, as well as the cost to homeowners to remove rotting trees that could threaten residences if they topple, New Hampshire state entomologist Pierra Siegert said on Friday.

Officials say the transportation of EAB - as well as other destructive, invasive pests - in nursery stock or firewood pose an ever-present threat in Maine and New Hampshire, where currently exportation out of county is prohibited.

Much of the migration of the pest is driven by firewood sale and transport. The bug can survive for long periods of time in a downed tree, Siegert said.

Currently in New Hampshire an intercounty quarantine is in effect for Strafford, Belknap, Hillsboro, Merrimack and Rockingham counties, prompting discussions among multiple agencies at the state level as to whether it's time to switch from a quarantine effort to a best practices model.

The feeling could be that the horses are already out of the barn, so maybe it's time to develop new strategies that mitigate further damages while seeking ways to eradicated the pest rather than trying to quarantine it.

The discoveries in Acton and Lebanon may bolster that argument.

Siegert noted that detection of the pest is part of a federal effort, but that since it was discovered in Concord in 2013, the response has been primarily state driven by agencies such as the Dept. of Natural and Cultural Resources, Dept. of Agriculture, Markets and Food, the USDA Plant Protection and the UNH Cooperative Extension.

She said the multi-pronged multi agency strategy focuses on detection, regulation, science-based test management, best management programs and outreach.

"Because it is flourishing throughout much of the state we no longer consider regulation to be as impactful," she said, adding that New Hampshire residents can voice their opinions on the best way forward at a state entomologist website nhbugs.org.

It is estimated that the EAB has cost municipalities, property owners, nursery operators and forest products industries hundreds of millions of dollars.

Ash trees comprise 4 percent of New Hampshire and Maine's hardwood forest, are a valuable timber species, and are also an important street tree. EAB threatens all species of ash trees (excepting mountain-ash). So far, there are no practical means to control EAB in forested areas, though pesticide treatments can protect individual trees.

The small beetles lay eggs on ash trees and the hatching larvae then tunnel under the bark.

Besides its wood burning qualities, ash is used to make baseball bats, snowshoes and canoe paddles among many other products.

If anyone thinks they may have EAB infesting trees on their property they should contact state officials through www.nhbugs.org or www.maine.gov.eab.