A popular shrub called Japanese barberry (Berberis thunbergii) remains on some garden center shelves in Connecticut in spite of attempts to have it added to the list of invasive species the state prohibits from sale.
State researchers found Japanese barberry plays a role in the rising population of diseased ticks, but local homeowners and businesses continue to buy and plant the shrubs. Denis Horgan of West Hartford, whose neighbors have multiple Japanese barberry’s in their yards, told the NBC Connecticut Troubleshooters he was troubled to learn of the plant’s connection to Lyme disease.
“Everyone knows about Lyme disease… anything that would add to that you’d think would be very well known,” Horgan said.
At least four northeastern states where Lyme disease is prevalent, including Massachusetts and New York, have barred Japanese barberry from sale. Though Connecticut recognizes it as an invasive plant, nurseries here both grow and sell it.
Representative Mary Mushinsky (D-Wallingford) fought to have Japanese barberry added to the list of 80 plants banned in our state. She claims the nursery industry lobbied against a ban because the barberry is a big seller.
“They’ve invested a lot and they don’t want to lose that investment. It’s as simple as that,” Mushinsky said.
In 2010, she agreed to drop the push for a ban after the Connecticut Nursery and Landscape Association (CNLA) volunteered to phase out sales of some varieties, but big box stores are not part of that agreement. Its invasiveness continues to worry Mushinsky.
“Every spring I open up the flyers that come in the paper and I see ads for the barberry,” she told the Troubleshooters.
The same year, state researchers discovered Lyme disease-carrying tick populations are 12 times higher than normal in forests infested with Japanese barberry.
University of Connecticut Forestry Professor Tom Worthley said removing Japanese barberry reduces the Lyme disease-carrying tick population by as much as 60 percent, but controlling the resilient bushes is no easy task.
“Just cutting it doesn’t control it,” Worthley explained as a crew of his UCONN students demonstrated how to use flame weeders, herbicide, or repeated cuttings over time to kill it off.
Worthley said it will be an uphill battle as long as invasive varieties of Japanese barberry are sold, but the Troubleshooters learned a potential solution is in the works.
Across campus at UConn, Dr. Mark Brand is hard at work breeding Japanese barberry that can’t reproduce. He explained that these sterile barberries will occasionally have seeds that are not viable, much like seedless watermelons and grapes.
Dr. Brand’s work has been funded in part by the USDA and the nursery industry. He told NBC Connecticut it is part of an effort to, “get rid of bad invasive forms of the plant but allow sterile forms.”
His sterile barberries are already in production in Connecticut and are exclusively licensed to independent nurseries for sale as early as 2018.
Mushinsky said she feels the development is a step in the right direction, but plans to introduce legislation banning sales of invasive Japanese barberry.
She explained, “you really have to put this plant in the forbidden list,” to slow the rising rate of infection in ticks and, in turn, humans.
The Troubleshooters reached out multiple times to the Connecticut Nursery and Landscape Association for this report, but they have yet to respond.
For more information on how Japanese barberry is connected to Lyme disease in ticks, click here.
To see how experts say to remove any Japanese barberry you may have near your home, click here.