Courtesy of Michael Griggs

This is the original tree found in Arnot forest with woodpecker scaling, which is a primary signal for Emerald Ash Borer beetle invasion.

March 16, 2018

Emerald Ash Borer Invades Tompkins County Forests

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Dark green forests, blue skies, fresh water and sunny days are what make Ithaca ‘gorges.’ Unfortunately, this aesthetic is under attack by none other than the infamous Emerald Ash Borer. The EAB is an invasive beetle species which has destroyed ash trees across the country and its detection in Tompkins County is no surprise.

The beetle was discovered in February in the Arnot Forest, which is Cornell’s largest teaching and research park at 4200 acres, by Mike Griggs, an entomologist at the U.S. Department of Agriculture’s Agricultural Research Service at Cornell’s Robert W. Holley Center.

While peacefully walking his dogs near the forest, Griggs was startled upon recognized deep “wood-peckering” or exposed inner bark on the ash trees, an innuendo for the malignant beetle. The woodpecker activity is a common symptom because the birds are attracted to the larva. While attempting to eat the larvae, the woodpeckers take off large parts of the bark; this is called “blonding” to represent the blond colored patches underneath the bark surface.

“That [wood-peckering] is 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.”

Griggs gained permission to look further into the bark only to affirm the existence of the Emerald Ash Borer. He found the species as larvae and as pre-pupae indicating that the invasion began years ago. In fact, Griggs added that the infestations are rarely found until the beetles are “well-established.”

Brett Chedzoy, a manager at Arnot, claimed his team anticipated the beetle’s invasion and actively monitored the ash trees for nearly ten years. Regardless of the preemptive management, the small emerald beetles were difficult to identify as they blend in with the greenery.

The bug is native to Asia and was first found in the United States in 2002 in Michigan. With a metallic, emerald green body and a purple abdomen, the Ash Borer goes from egg to larva to pupa to adult in two years. Adult females lay eggs in bark crevasses to produce larvae that feed on the inner bark agitating the water and nutrient system in the tree. Through this attack on the tree’s vascular system, the bug can kill a tall, strong, beautiful ash tree within two or three years. Emerald Ash Borers only attack on the 16 Ash tree species. In the area of Arnot, there are three native species – the white, black and green ash trees.

“Based on the experiences from more mature EAB infestations, severe Ash mortality is expected.” Chedzoy said. “Once the food source [Ash trees] is gone, the EAB population will also disappear until Ash seedlings and saplings become large enough to support a new infestation of EAB- this may be a decade or two down the road. Hopefully by then, we will have more biological controls (natural predators) of EAB in place to prevent widespread mortality.”

Previously, the pest was detected about 20 miles west of Arnot in Schuyler County and about 20 miles south in Tioga County. Griggs also discovered the Ash Borer in 2009 along Route 17 in Cattaraugus County, NY.

“The bug is in 30 other states and has destroyed all native ash it has encountered.” Griggs said.

The Arnot forest is managed by the Department of Natural Resources in the College of Agriculture and Life Sciences. Ash trees make up 15 percent of the forest and are very valuable. In fact, before the EAB infestation in the U.S., there were 8 billion ash trees in the U.S. valued at $282.35 billion for timber use.

Ash trees are a vital part of ecology in Central New York in both urban and natural forests. This infestation is going to take the widespread ash population by the storm.

“It has been extensively researched, unfortunately more and more points to the inevitability of us losing 99% plus of all ash.” Griggs said.

It is vital to note that trees and human health have a strong connection. In fact, the American Journal of Preventive Medicine claims the disappearance of ash trees is related to an increase in deaths from cardiovascular and respiratory diseases in humans here.

“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,” Chedzoy said.

It is good that immediate action is being taken. Since the Ash Borer arrived a couple years ago and is now settled in the community, insecticides are unlikely to do the trick to eradicate them.

Alternatives to eliminating the invasive species would include biological controls such as natural predators of the Emerald Ash Borer. One of these biocontrols involves three parasitic wasps, which are established and under monitoring. Unfortunately, these wasps will only do so much.

“They may not be able to thwart the initial “wildfire” that we will initially see.” Griggs said. “I would speculate that they [wasps] may be important once ash begins to grow back, but we will never see ash growing in the densities we do today.”

Most recently, the bug has been detected near Watkins Glen, which is 20 miles west of Arnot. The EAB has a strong ability to spread. There is no doubt the widespread ash tree population in central New York is under attack.

“The many thousands of Ash trees that will die in the next few years in this area near roads, homes, powerlines, parking lots, trails, etc. will be challenging and expensive to deal with.” Chedzoy said.