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Devastating emerald ash borer discovered in Arnot Forest

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Lindsey Hadlock

Emerald ash borer larvae feeding under the bark of an ash near Chili, NY.

The emerald ash borer – an invasive beetle that has destroyed ash trees across the country – has been detected for the first time in Tompkins County in the 4,200-acre Arnot Forest, Cornell University’s largest teaching and research forest.

The arrival of the pest is not exactly a surprise. Arnot Forest land managers anticipated the insect’s spread and have been actively managing the forest’s ash trees for a decade. Ash accounts for about 15 percent of the total number of trees in Arnot Forest and are valued at many hundreds of thousands of dollars.

“For the past 10 years, we’ve been trying to preemptively salvage some of the more valuable ash timber by managing the forest in a way where we can try and transition it to what’s going to replace the ash,” said Brett Chedzoy, Arnot Forest manager. “When you abruptly lose an entire species, especially an important one like ash, you create a void that nature fills with invasive plants and things that are less desirable.”

Three thousand acres of Arnot Forest are actively managed. Preemptive harvesting of ash on the managed portion of land fits into a larger management policy of harvesting timber to sell to sawmills or buyers, a regular practice to keep the forest healthy and sustainable, Chedzoy said. The remaining 1,200 acres are not harvested as they contain sensitive areas, such as ravines and wetlands, or because harvesting would conflict with ongoing research. Also, several hundred acres of this unharvested acreage are devoted to maple sugar production.

Leaving some ash unmanaged could also be beneficial, according to Mark Whitmore, Cornell forest entomologist.

“One of the most important things for people to do is to notice ash trees that survive an emerald ash borer outbreak,” Whitmore said. “These trees may be resistant and would be very important sources of seed or genetic resources, for future forests.”

Mike Griggs, an entomologist at the U.S. Department of Agriculture’s Agricultural Research Service at the Robert W. Holley Center on Cornell’s campus, made the initial discovery of emerald ash borers in February. He lives near the Arnot Forest and was walking his dogs when he noticed an ash that woodpeckers had pecked. “That’s a major sign this time of year that something is wrong with that tree,” Griggs said. “Being an ash, there is not a whole lot else that would cause ‘woodpeckering’ to that degree.”

After getting permission to peel back some bark, Griggs confirmed the presence of emerald ash borer larvae and pre-pupae. The infestation likely began many years ago.

“You don’t find these infestations until its fairly well established,” Griggs said.

“Now that we know the bug is there, we will look more closely at other parts of Arnot Forest and other properties managed at Cornell,” Chedzoy said. “The trees won’t die overnight, but now we know we have a couple of years instead of five or six years to react to this.”

Arnot Forest lies within Schuyler and Tompkins counties. The pest had previously been detected about 20 miles west of Arnot Forest – in far western Schuyler County, about 20 miles south near Waverly on Route 17 in Tioga County – and near Cortland.

Along with culling healthy trees for timber, management strategies could include identifying valuable trees and injecting them with insecticide and for people to avoid moving firewood as it can spread bugs more rapidly, an important strategy for wood-borne pests.

Griggs is credited with making the first discovery of emerald ash borers in New York state in 2009, when he spotted some damaged trees while driving with a colleague along New York Route 17 near Randolph, in Cattaraugus County in southwestern New York.

Native to Asia, the invasive pest was first discovered in the U.S. in Michigan in 2002. Emerald ash borers have four life stages: egg, larva, pupa and adult. Adults fly and have metallic emerald green bodies and coppery red or purple abdomens. Adult females lay their eggs in bark crevasses; the larvae burrow and feed on the inner bark and disrupt water and nutrient flow in the tree, killing it in two to three years.

The Arnot Teaching and Research Forest is managed by the Department of Natural Resources in the College of Agriculture and Life Sciences.

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Krishna Ramanujan