The latest round of plants added to Pennsylvania’s noxious weeds list reads like a directory of popular landscaping options.
Japanese barberry (Berberis thunbergii), callery or Bradford pear trees (Pyrus calleryana) and Ravenna grass (Saccharum ravennae; Tripidium ravennae) have been staples of urban and particularly suburban landscaping for decades. All three are invasive species whose seeds are readily spread by bird droppings. But the barberry is a particular problem for multiple reasons, according to plant biologists.
First, native animals do not browse it for food. That has made it very popular as a landscaping plant, but it also makes it that much easier for barberry to spread to new areas.
Second, its sharp spines make it an ideal hideout for the white-footed mouse, the main source of Lyme disease in Pennsylvania. Black-legged ticks also love the humid atmosphere inside the closely packed leaves of a barberry plant. And with plenty of white-footed mice to feed on, more ticks then acquire Lyme in the state that already ranks No. 1 in the U.S. for Lyme disease infections.
But even as the commercial sale of barberry and other entries on the noxious weeds list is being phased out — sales will be completely banned by 2023, according to state agriculture officials — local nurseries aren’t all that worried about lagging sales.
“Most people who want barberry really just want something colorful,” said Chris Wright, a horticulturalist at Plumline Nursery in Murrysville. “But it’s also easy to grow, and if that’s what people are looking for, there are lots of options like chokeberry and grow-low sumac. Those are tough-as-nails shrubs.” Master gardeners at the Penn State Extension suggested coralberry, inkberry holly, winterberry holly, Virginia sweetspire and Northern bayberry as substitutes for barberry shrubs.
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