Japanese barberry could use a good press agent about now. Not only is this popular plant currently classified as invasive in 20 of the 32 states where it is established, but research shows that it may play a role in the spread of Lyme disease as well. And odds are, it’s in your yard.
Widely used throughout the Midwest, Japanese barberry was brought to the United States in the late 1800s. The prickly shrub with attractive red fall foliage was tough—able to deter deer while being tolerant of full sun, dense shade and drought. All was well until it forgot its good manners and started taking over forests and woodlands, choking out other plants.
“It’s hard to tell which plants will become invasive in a new setting, and it took a long time for Japanese barberry to show its true colors,” says Kayri Havens-Young, Director of Plant Science and Conservation at the Chicago Botanic Garden. “Like many invasive species, it’s been marketed well and the green industry doesn’t want to remove a plant that sells and makes money unless there are issues. But our ecologists have seen it escape into woodlands and ravines along the Lake Shore. And we know it’s created a huge problem on the East Coast that we don’t want to repeat here.”
That “East Coast problem" is top of mind for former Cleveland resident Jeffrey Ward who serves as chief scientist with the Connecticut Agricultural Experiment Station. In an ongoing study of Japanese barberry, Jeffrey and his colleagues made an unanticipated discovery linking Japanese barberry with blacklegged ticks—the little suckers that carry the causal agent for Lyme disease. Turns out barberry creates the ideal humid environment for ticks, Jeffrey says. And that explains the research finding that woodland areas with dense Japanese barberry had up to 120 disease-carrying ticks per acre while a forest without barberry had just 10 Lyme-disease-ticks per acre.
“Unfortunately this is also an issue up in Wisconsin, where there are lots of woods,” Jeffrey says. “If this problem isn’t in your neighborhood yet, it’s coming. And it affects dogs and horses, too. ”
So what to do with Japanese barberry in your yard? “If you have a barberry hedge, you don’t have to rip it out,” says Kayri. “But as you refresh your garden and plants die, switch it out with species that aren’t a problem.” Suggestions include ninebark (Physocarpus opulifolius), pictured lower right; highbush blueberries (Vaccinium corymbosum), pictured upper right; and clover currant (Ribes odoratum), pictured at left.
Having trudged through numerous tick-infested woods, Jeffrey is more inclined to hurry the elimination process. “Dig them out if you just have a few,” he says. “I guess the message is to manage your property. It’s what’s best for the environment and you.”
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