Japanese Barberry Berberis thunbergii DC

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A campaign to raise awareness of and control invasive plants sponsored by Granby’s Conservation Commission

Find it

A dense bush 2 to 7 feet high, Japanese Barberry has spikey thorns every inch or so along each branch. Small leaves along the branches are green in spring and summer. In the fall it’s easy to identify: the leaves turn bright colors—red, brown, purple, orange—and bright red berries hang in rows along the branches into the winter. Over time, it forms dense, impenetrable concentrations, in full sun or in the partial shade of a forest. It tolerates a wide range of growing conditions, including drought.

Why it’s a problem

Japanese Barberry was imported to the U.S. in the late 1800s and widely planted in landscapes, often as hedges to prevent through passage or in problem areas where other plants did not grow. Once established, it forms dense thickets that crowd out other plants, change soil chemistry and inhibit forest regeneration. It spreads by seeds, transported mainly by birds. 

Lyme-disease-carrying-ticks love Japanese barberry. UConn’s Agricultural Experiment Station found 10 times more ticks that carry the disease in forests with Japanese barberry. This is probably because the dense thickets are humid, which the tick larvae need, and because they provide protection for white-footed mice, that carry the organisms that cause Lyme disease. 

What to do

Do not plant it. Numerous varieties continue to be used in landscaping despite their tendency to escape and become invasive. The only safe exceptions are sterile varieties, including some developed by Dr. Mark Brand at UConn.

Remove it. Pull or dig out small plants by the roots as soon they appear to prevent them from spreading. Plants too large to dig out will likely need a two-step approach. First, cut the plant at the base and dispose of it without allowing the seeds to disperse. This can be done in the fall and throughout the winter. Second, when the stump sends out fresh growth, use a propane torch to burn it. Glyphosate (Roundup) is also effective, but do not spray. Instead, cut the stems and use a small paintbrush to paint the cut ends to minimize risk. It may be necessary to repeat these steps.