On a wet, humid morning in Murrysville's Townsend Park, Bill Davis grimaced as he yanked out a section of barberry bush and added it to a 6-foot-tall pile of brush behind him.

“Ticks just love this stuff,” he said.

Pennsylvania is in the midst of its latest severe tick season, and invasive species like barberry are not helping.

“Deer won't eat these, so the ticks congregate on it,” said Davis, one of a half-dozen volunteers working with Friends of Murrysville Parks to clear invasive species from the park on June 13.

The group formed in 2006, but president Pia van de Venne has been working to clear invasive species from Murrysville parks since 1999.

“Townsend is not a major park, but it used to be farmland, and so plants grow here very easily and quickly,” she said, ducking under a log to reach a stand of the invasive multiflora rose. “We pull the plants, and if we find some with seeds, we'll bag those.”

At Townsend, multiflora rose bushes and Japanese honeysuckle vines are the most prevalent invasive species. Van de Venne also finds a few garlic mustard plants as she traverses the narrow trail through the park.

“In its second year, garlic mustard goes to seed and produces little black seeds,” she said. “They're actually very tasty with a little bit of spice.”

Then she added, with a laugh: “But eat them all, so it doesn't spread.”

Invading the city

Unchecked, invasive species can have quite an impact.

In Frick Park, Pittsburgh Parks Conservancy crews recently discovered a massive stand of bush honeysuckle that formed a 2.6-acre wall that covered up 10 full-grown butternut trees.

Phil Gruszka, the conservancy's director of horticulture and forestry, said he worked with city public works crews to bring in machinery to help remove the honeysuckle.

“If we had gone in and tried to do that work by hand with volunteers, it would've taken months,” Gruszka said.

In city parks, garlic mustard also is prevalent, and conservancy workers are always on the lookout for new invasives.

“There's new plants that are moving in all the time,” he said. “Mile-a-minute is one that's starting, and also Japanese stiltweed.”

Removing invasive plants clears space for native flora nd contributes to the overall health of a forested area.

Ellen Yerger, an associate biology professor at Indiana University of Pennsylvania, is studying Duff Park in Murrysville as an example of a healthy park ecosystem, in part because of the work that van de Venne and her group have done.

“I don't know of anyone other than Pia who does this,” Yerger said. “She's even trained other people who just go to walk their dogs to recognize things like garlic mustard, pick it and place it in a bucket that another volunteer comes and empties.”

In addition to choking out native plant life and competing for sunlight and soil nutrients, invasive plants can create what Yerger called “ecological traps.”

Cardinals, for example, eat red berries from native plants, which contributes to their bright red coloration. But if they eat red berries from the Japanese honeysuckle vine, “they have less protein and fat in them,” Yerger said. “There's been other documentation where a (butterfly) will lay eggs on an invasive plant, because it thinks it's the right plant to feed their larvae, but when the larvae hatch, they can't actually eat the plant.”

Time always right

Around the end of fall and start of winter is ideal for clearing invasive species.

“The native vegetation drops off,” Davis said. “And the invasives keep their leaves longer, which makes them easier to find.”

Gruszka agreed.

“Tree species like Norway maple are still green when our native trees are turning yellow and orange, and it's a great time to go after them,” he said.

Wet weather also provides an advantage, allowing root systems to come out of the ground more easily.

But anytime of year is the right time for rooting out invasives.

In Southwest Pennsylvania's state forests, ecological services section chief Rebecca Bowen said the Department of Conservation and Natural Resources is working with a West Virginia researcher to use a natural fungal pathogen, “to see if it can be turned into an herbicide to treat Tree of Heaven plants.”

In 2017, John Brundege, a DCNR forester who covers Jefferson and Armstrong counties, brought the Verticillium fungus to try and help eradicate the plant, also called the ailanthus tree. The fungus will produce a wilt, clogging the tree's vascular tissue and killing it.

The fungus is not known to harm native tree species.

Van de Venne, 76, said she plans to continue her work until she turns 80.

“I won't clear Townsend Park in my lifetime, but hopefully we will finish Duff Park,” she said. “That's the one where I've been working the longest.”

Aaron Wattenphul of Greensburg, who helped this week, is a perfect example of how the work of Friends of Murrysville Parks can continue.

“I used to come down with my mom and do this when I was younger,” he said. “I don't mind coming down. I got some time.”

Patrick Varine is a Tribune-Review staff writer. Reach him at 724-850-2862, pvarine@tribweb.com or via Twitter @MurrysvilleStar.

---

Copyright ©2025— Trib Total Media, LLC (TribLIVE.com)

---