The invasive shrub, Japanese barberry (Berberis thunbergii) was first introduced from Japan around 1875. This species has been a favorite ornamental shrub in yards, as hedges, and along highways because of its scarlet fruit and orange-red autumn foliage.
Japanese barberry is a compact, spiny, deciduous shrub with arching branches of dense foliage. It commonly grows from two to three feet tall and has been known to reach heights of six feet. Branches also root freely when they touch the ground; thus single plants can become quite large. The plant regenerates by seed and creeping roots.
Small, rounded, smooth edged leaves are clustered in tight bunches close to the branches. Small yellow flowers bloom in May singly or in small clusters and form bright red oblong berries that mature in mid-summer and persist into winter. Single spines approximately ½" long occur along the stems. The inner bark and roots are yellow.
It typically grows in locations with partial sunlight such as woodland edges. However, it can survive well under the shade of an oak canopy. In young forests it can form thorny thickets that shade out and limit the growth of native plants. It is also often found along roadsides, fence rows, old fields, and open woods.
Herbicides are suggested to control plants that are difficult to remove mechanically by pulling. Glyphosate (e.g., Accord XRT II) is effective when applied as a foliar treatment. Foliage can be sprayed up until the leaves begin to change color in the fall. Best results are achieved during periods of active growth and full leaf expansion. Triclopyr ester (e.g.,
Garlon 4 Ultra) has also proven to be effective at controlling barberry when applied as a basal stem or cut stem treatment. Basal bark treatments are effective in early spring when the barberry and other invasive shrubs first leaf out. The spray wand can be moved around the base of plants and individual stems sprayed from the root collar up to a height of one - two feet. More information on identification and control can be found in the following two fact sheet from Penn State.
Penn State Extension Invasive Plant Fact Sheet: Japanese Barberry
Penn State Invasive Species Quick Sheets: Exotic Shrubs
In addition, the University of Minnesota Extension has produced a new 3-minute video on the invasive Japanese barberry