Protecting Greendale Cemetery's hemlock trees from deadly infestation
The treatment was required — death was all but certain without it — but the needle required to apply it was almost cartoonishly large. It was so big, in fact, that it came with a foot rest so the man wielding it could step down with all his weight, forcing it in as he pumped down with both hands on the plunger, looking for all the world like he was running a jackhammer.
Despite the alarming sight, the patient, towering above, head in the clouds, seemed blissfully unaware of the life-saving procedure taking place at ground level.
The injector was repeatedly plunged — again and again, 56 times as the applicator made his way in a circle around the treatment area — but the patient remained stationary, swaying a bit in the cool breeze but otherwise stoic.
The entire process took only a minute shortly after noon Wednesday but is expected to prevent a deadly infestation for three to five years at the cemetery on Randolph Street.
The eastern hemlock in the Greendale Cemetery ravine that played the role of patient wasn't receiving a vaccination prior to flu season. Instead, the earth around the base of the tree was being treated with imidacloprid, a nicotine-like insecticide. The application was meant to halt the spread of hemlock woolly adelgid, an aphid-like insect that feeds by sucking the sap of hemlocks. Infested trees soon begin losing their needles and typically die in less than a decade.
The invasive pest is native to Asia and was spotted in southeastern Pennsylvania in the 1960s after accidentally being introduced in Virginia in the 1950s, according to Pennsylvania Department of Conservation and Natural Resources (DCNR).
This spring, hemlock woolly adelgid was spotted on a handful of trees in Greendale for the first time, not long after the pest was detected in Crawford County for the first time, according to Luke Brooks, French Creek Valley Conservancy (FCVC) conservation coordinator who was wielding the injector used to apply imidacloprid. As the pests spread across the state, Crawford County was one of the last counties in which they were detected, Brooks said.
"It's an aphid that attacks hemlock trees — it sucks the sap through the needles," he continued. "When you see it, it'll look like little, tiny cotton balls all over the needles of the tree."
Hemlock woolly adelgid has only been found on a handful of trees in Greendale so far, but given the certainty of the prognosis, officials from the cemetery, the conservancy and DCNR determined that a swift, organized response was necessary.
"It's pretty much always fatal for the hemlock trees," Brooks said. "The clock is ticking."
Joining Brooks in the ravine this week was Greendale Superintendent Patrick Groover, who noted the challenge of treating trees scattered across the steep ravine walls over approximately 15 to 20 acres located at the northern end of the ravine, which itself runs through a conservation easement of approximately 75 acres that is managed by FCVC.
Groover also noted the significance of the hemlocks. Not only is the eastern hemlock Pennsylvania's state tree, but the many examples found at Greendale include some that are believed to be well over 100 years old. As Groover and Brooks stood at the base of the specimen Brooks had just treated Wednesday, which had a diameter at breast height of 28 inches, they gazed up and speculated on its height, agreeing that it was both hard to gauge from directly below but also certainly well over 100 feet tall.
Mature eastern hemlocks have a maximum height of 160 feet, according to the U.S. Department of Agriculture.
"There's a lot of history to them," Groover said of Greendale's hemlocks. The choice in the face of woolly adelgid is either to treat the trees to preserve that history, he added or to have "a bunch of dead trees lying around" Greendale's ravine.
Last week, orange ribbons marking the tree locations and diameters were placed throughout much of the ravine. The imidacloprid is applied in a circle twice the size of the diameter at the base of the tree. Brooks estimated that this week he and Groover would treat more than 5,000 inches of diameter length as they made their way from tree to tree. Trees within about 15 feet of Cemetery Run, they added, won't be treated in order to keep the insecticide away from the stream.
The treatment process has been facilitated by two important steps taken years ago: the perpetual conservation easement established in 2018 that put the ravine area in the care of FCVC and the legacy of former Meadville chiropractor David Shryock. In 2016, Shryock left a $100,000 gift to Greendale as part of his will to be used to protect the hemlock trees from woolly adelgid and other invasive species.
Also helping is the ability to perform the treatments "in house," said Brooks, who holds a pesticide license. The approximately $2,000 spent on injectors and insecticide is significantly cheaper than hiring a contractor to perform the work.
Despite the threat posed by woolly adelgid and its presence in Greendale, Brooks was optimistic about the outlook for the ravine area that has served as host to so many generations of Meadville hikers — an experience characterized in large part by the towering hemlocks whose efforts to find sunlight from deep in the ravine now provide the shade visitors enjoy by Cemetery Run.
"There's such a good partnership between the conservancy, the cemetery, DCNR," he said. "There's lots of eyes on this."
Preserving the hemlocks would go a long way toward preserving the spirit of the ravine, as Brooks noted just before heading down the Shryock Memorial Trail from the cemetery's new green burial section.
"You'll see," he said. "It's almost church-like down there.
"It's pretty incredible."
