Herd of hungry goats brought in to nosh on invasive knotweed along Harmony Trail

Clearing highly invasive Japanese knotweed along the Harmony Trial can be backbreaking work for volunteers trying to maintain the mile-long bucolic walking and biking path.

But for a dozen goats and their donkey protector, keeping the ornamental plant from crowding out native species is just another chance to chow down to their heart’s content.

From Sept. 13 to 23, the herd from Allegheny GoatScape will focus their attention on the hillside near the western terminus of the Rachel Carson Trail, which stretches 47 miles to Harrison Hills Park, said Bob Mulshine, a volunteer for the Rachel Carson Trail Conservancy.

“We’ve gone out to try to clear the hillside with weed trimmers, but it’s a bit tricky because the slope is steep, making it hard to get a solid footing,” he said. “The goats have no problem at all, so they’re very helpful.”

Left unchecked, knotweed will overtake the entire Wexford Run Valley where the trail runs through, he said.

Japanese knotweed was introduced from East Asia in the late 1800s as an ornamental and to stabilize stream banks, according to the Penn State Extension, an educational network that provides access to the university’s resources and expertise.

Mulshine said the weed is difficult to destroy.

“It can reproduce through its root system, through flowering or if a branch breaks off into a puddle of water,” he said. “So it has a big advantage in terms of being able to recreate itself.”

Volunteers typically try to cut the weed down to its roots in June after the plant has used up all of its stored energy from the previous year and again in late summer or early fall when the plant begins to flower and drop seeds, Mulshine said.

Knotweed is a “highly a successful invader of wetlands, stream corridors, forest edges and drainage ditches across the country,” according to the extension service.

The goats and Diamond the donkey — who protects them from coyotes and curious dogs — are penned in with a solar-powered fence that produces a mild shock when touched. Once they’re done with a section, the herd is moved to the next section of trail.

“That’s incredible. I was reading the sign and it was kind of shocking that they can do that to control the plants,” said Lauren Gyory of Pine, who spotted the herd while hiking the trail for the first time with her daughter, Liv, 2, and son, Leo, 11 months. “It’s kind of neat. We’ll be back to see them again.”

The Harmony Trail, which runs along a former trolley line, is one of three maintained by the conservancy.

People who want to view the herd at work can access the penned area from the Harmony Trail parking lot at the intersection of Wexford-Bayne and Brennan roads. The pen is about a half-mile down the flat walking and biking trail.