NOTE: This story was originally published on September 22, 2017
With reporting by Paige Walter
It would be an understatement to say that Ryan Utz is not a fan of Japanese barberry.
Utz is a professor at Chatham University’s Falk School of Sustainability, and as we walk through some damp, forested land on the property of their Eden Hall campus, north of Pittsburgh, he can hardly contain himself.
“This is what we call barberry hell,” he says, laughing a little, but not because he thinks it’s funny. It’s more like disbelief. “That’s going to be all that you see.”
Utz has some other choice words for the thorny, shoulder-high shrubs we see all along the tree line; he calls them insidious and alarming. That’s because of what’s just beyond the wall of barberry.
“We have a nice population of mature oaks, cherries and red maples here,” Utz says. “But based on our research, everywhere you see barberry, which as you can see right now is pretty much everywhere, there are no young trees underneath it.”
LISTEN: “Please Don’t Buy Japanese Barberry. Forests Will Thank You.”
Last year Utz and some of his students did a survey of trees here on campus. They noticed that even a small patch of Japanese barberry seems to inhibit new generations of native trees.
“Barberry grows very thick and very dense, and because of that can limit a lot of the resource of sunlight,” says Art Link, a graduate student at Chatham.
But barberry doesn’t mind the shade. And unlike native saplings, it’s not popular with deer grazing in woodlands. Link has set up a number of study plots on campus, looking for some other answers for why barberry is muscling out native trees.
Japanese barberry was introduced from Asia in the late 1800s as an ornamental. It was used to create a natural barrier in fields, and many still favor it for front lawns and gardens because it has pretty, spoon-shaped red leaves, and colorful berries. Growing in the forest, Japanese barberry loses its rosy hue, and spreads easily. Plentiful seeds from the berries are dropped onto the forest floor, or spread by birds. Weedy stems of barberry also can root themselves into the ground, starting new plants.
So just how big a problem is barberry in Pennsylvania’s forests?
“It’s quite a large problem, actually,” says Kelly Sitch, an ecologist with the Pennsylvania Bureau of Forestry.
Sitch says the health of any ecosystem depends on the diversity of species that live there. Japanese barberry and other invasives upset that balance. And its berries aren’t really nutritious for wildlife, the way that junk food isn’t ideal for people.
Barberry also makes a home for mice, and by extension, the deer ticks they host. Those are the black-legged ticks that carry Lyme disease.
“In areas where barberry remains uncontrolled, research has found that the incidence of ticks per acre that are infected with Lyme disease is actually much higher than in areas where it’s being controlled or where it’s not present in forests,” Sitch says.
Sitch says each year the state’s foresters and biologists prioritize removal of invasives. Depending on the particular piece of land, sometimes barberry makes it to the top of the list. But it’s been on the landscape so long, and is so well established in certain areas, that often other invasives are a bigger priority. For example, wavyleaf basketgrass is a new invasive in Pennsylvania which spreads quickly. There’s a greater chance that the grass could be eradicated if stopping its spread is a priority.
But Sitch says that doesn’t mean he and others aren’t worried about Japanese barberry. It’s not easy to control or remove. Young barberry plants can be pulled out easily, by hand. More established Japanese barberry plants can be removed mechanically, if that doesn’t disturb the soil too much, or scatter seeds. In some situations herbicides are applied.
At Chatham University, Ryan Utz and his students slice the plants with hedge trimmers, almost down to the level of the dirt, so that the curiously yellow inner stems of the barberry are showing. Then if it’s not too dry in the wooded area where the barberry are growing, the stems are burned for a short period of time with a torch. This has to be done twice because the barberry often grows back.
But Kelly Sitch and Ryan Utz agree when it comes to the best way to keep Japanese barberry out of Pennsylvania’s forests.
“Please, don’t buy barberry,” Utz says.
Though it’s been banned in a some states, many nurseries and big box stores still sell Japanese barberry for landscaping in Pennsylvania. Utz says there are other, non-invasive species of barberry available, and he’s a lot less prickly about those.
Photo (top): Japanese barberry was introduced from Asia in the late 1800s and is favored for its spoon-shaped leaves and colorful berries. Credit: Paige Walter