Take on Invasives: Japanese barberry

This is the first in a monthly series on invasive plant species in Northern Michigan, their impact on natural landscapes and what can be done to help control and prevent their spread.

One of Northern Michigan’s most aggressive invasive species can be purchased at many local garden centers as an imported ornamental shrub with leaves that change from green to a purple or burgundy shade through the season.

In areas where it takes hold, Japanese barberry outcompetes every other plant. This means the flowers, trees and shrubs that provide pollen, nutrients and habitat which support native wildlife don’t have a chance to grow. Left unmanaged, barberry forms a thicket, upwards of 6 feet tall, of snarled and thorny branches. Once it spreads, it grows without interference because its thorns keep deer and other wildlife at bay. Additionally, birds eat its fall fruits and pass the seeds in their droppings, furthering its spread.

A tangle of barberry shrubs in late summer.

“That’s what makes it a perfect invasive species,” said Shelby Bauer, Stewardship Program Coordinator who oversees the Huron Heartland Invasive Species Network. “It spreads quickly and it withstands most natural threats.”

Bauer’s first encounter with a barberry invasion happened at a privately owned clearcut, where the newly abundant sunlight spawned a sea of barberry shrubs that choked out any potential for native tree seedlings to grow.

The ripe fruits of Japanese barberry appear in late summer and last well through fall. Eaten by birds, the seeds are easily spread across the landscape in their droppings.

“It was an impassable wall,” she said. “That was also my worst tick day, because small mammals are drawn to these thick barberry shrubs and ticks follow those animals.”

If caught early, infestations can be kept in check. Individual plants can be hand-pulled — wear gloves and eye protection — and larger patches can be cut then treated with herbicide. Plants should be removed ahead of any forestry activity, since machinery can disturb soil and spread seeds across areas newly exposed to sunlight.

Most importantly, when planning your landscaping, avoid Japanese barberry and plant a native shrub like ninebark instead. You can report suspected barberry infestations to the Midwest Invasive Species Information Network (MISIN) at misin.msu.edu.

The Huron Heartland Invasive Species Network is made up of conservation groups, landowners, state and federal agencies that seek to restore native habitat through invasive species education, prevention and management. The Huron Heartland ISN is led by Huron Pines with support from the Michigan Invasive Species Grant Program (Michigan.gov/Invasives).

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