BELCHERTOWN — An iconic red oak at the main entrance to Quabbin Park will be coming down before winter, the mostly dead tree deemed a public safety hazard to those using Winsor Dam Road.

Dan Clark, regional director of the Quabbin and Ware River watersheds, made the announcement at Monday’s meeting of the Quabbin Watershed Advisory Committee, saying the landmark oak had succumbed to successive years of gypsy moth infestation and has also further stressed by past years of drought.

Mr. Clark said the loss of the oak is emblematic of the approximate 2,000 acres of dead or dying red and white oak across the more than 80,000 acres of watershed controlled by the state Division of Water Supply Protection.

The Quabbin director said oak is the dominant hardwood tree species in the canopy, and while the loss is significant, it does not represent any threat to the viability of the watershed that filters the 412-billion gallon reservoir.

“The percentages that each tree species represents may change over time, but other species will move in,” he said.

Mr. Clark said Quabbin foresters had been focused on salvaging the diseased red pine plantations, but have moved to salvage dying oaks instead while they still had commercial value.

The Quabbin director told QWAC members the alarming news is that an expected collapse of the gypsy moth population after successive years of heavy infestation did not materialize, and defoliation in the 2019 growing season could be as destructive as this year's.

Professor Joseph Elkinton, University of Massachusetts at Amherst entomologist, said he’s mystified as to why the Entomophaga maimaiga fungus failed to decimate the population as it did in 2017.

“The fungus thrives and works best in moist conditions, and certainly there was ample rainfall in May and June,” Mr. Elkinton said.

He said the defoliation in the Amherst and Quabbin areas was concerning, and the evidence of gypsy moth egg masses in the region suggests another round of defoliation next year.

“I’ve worked on gypsy moth and gypsy moth pathogens for decades at the lab here at UMass, and frankly I’m baffled by what I’ve seen this year,” Mr. Elkinton said.

The researcher added, “In the past, it didn’t matter whether there was a low density or high density gypsy moth population. If the conditions were right, the Entomophaga maimaga fungus knocked back the population to very low levels, as in 2017. That didn’t happen this year in this region, and I have no idea why.”

Clif Read, director of interpretive services at Quabbin, said the Quabbin forestry crew will be removing the tree at the park sometime this fall.

“We are hoping to be able to salvage some of the tree for boards that will be used for some appropriate project in the future. We don’t know exactly what yet, because it will depend on the quality of the wood that results.”

He added that DCR will also plant a new tree in the general location at some point in the future.

Ken Gooch, Forest Health program director for the Dept. of Conservation and Recreation, said the levels of gypsy moth defoliation this year were surprising in light of last year’s caterpillar die-off from the E. maimaiga fungus.

As a result of several years of defoliation and the added stress of drought before last year, Mr. Gooch said there has been significant oak mortality.

The program director said his crew will be removing the Quabbin oak and nearly a dozen dead and dying red oaks near the west entrance to Quabbin Park.

“Given what happened a year ago with the die-off from the E. maimaiga fungus and the nucleopolyhedrosis virus, we were expecting the same result this year. It didn’t happen, and we don’t know why,” he said.

The program director said an estimated 175,000 acres were defoliated this year by gypsy moth statewide. While a gypsy moth egg mass survey will be conducted in October, anecdotal evidence suggests there will be substantial defoliation again next year in those areas hard hit this year.