Non-native barberry (Berberis spp.) are invasive, shade-tolerant, deciduous woody shrubs found in Ohio and surrounding states’ natural landscapes and forests. Recent research has indicated a relationship between high tick populations and the presence of the invasive shrub, making it crucial for forest and landscape managers to be able to identify it, manage it, and prevent its spread into natural and managed areas.
Common barberry or European barberry, Berberis vulgaris, was intentionally introduced to North American landscapes in the1600s by European settlers. It escaped cultivation and spread throughout the northern United States. Common barberry poses a serious threat to grain production in the U.S. by acting as an alternative host for the disease, black stem rust, caused by the fungus Puccina graminis. As a result, state and federal agencies began an eradication campaign (USDA ARS 2016). Unfortunately, populations still persist in the northeast, as shown on this distribution map of B. vulgaris.
Japanese barberry, Berberis thunbergii, is another non-native shrub marketed as an ornamental replacement to common barberry that would not transmit black stem rust. While Japanese barberry was a popular selection due to its deer-resistance (due to thorns) and purple fall color, it too became an invasive species in forests and disturbed areas.
Both non-native barberry species are invasive. They have shown up on several states’ noxious weed lists and are banned from sale and propagation. They are not recommended plantings for the landscape and should be eradicated when found in natural areas in Ohio.
|Common barberry||Japanese barberry|
|Berberis vulgaris||Berberis thunbergii|
|Mature height: 8–10'||Mature height: 3-6'|
|Mature width: 4–6'||Mature width: 3-8'|
|Leaf margin: sharply toothed simple leaf||Leaf margin: smooth simple leaf|
|Flowers: ½" and pale yellow||Flowers: ½" and white to yellow|
|Fruit: small, egg-shaped, and colored a red-purple||Fruit: small, egg-shaped, and colored a red-purple|
These two barberry species may be confused. Two key identifiers of the Japanese barberry are the yellow cambium layer under its bark and its yellow roots. These attributes distinguish it from the European variety. Also note the difference in leaf margin between the two species. Common barberry has sharply toothed leaf margins and Japanese barberry has smooth margins.
|Figure 1a. Common barberry leaf showing toothed margins. Photo by Leslie Mehrhoff, University of Connecticut, Bugwood.org.||Figure 1b. Japanese barberry leaves with entire margins in two color variations. Note that purple varieties can lose their color and remain green in shaded environments. Photo by Leslie Mehrhoff, University of Connecticut, Bugwood.org.|
|Figure 2a. Common barberry thorns showing triple branching. Photo by Leslie Mehrhoff, University of Connecticut, Bugwood.org.||Figure 2b. Single thorns on Japanese barberry. Photo by Leslie Mehrhoff, University of Connecticut, Bugwood.org.|
The thorns (technically spines) are also an identifier of the type of barberry, especially in winter. Japanese barberry has spines that arise singly (Figure 2b) while common barberry spines are branched (Figure 2a) in groups of two or three. Barberry thorns are very thin, some as fine as a syringe. They are brittle and easily dislodge in gloves, skin, or fur due to their high silica content. Proper protective gear is recommended when managing barberry to protect against punctures.
|Figure 3a. Common barberry flowers. Photo by Leslie Mehrhoff, University of Connecticut, Bugwood.org.||Figure 3b. Japanese barberry flowers. Photos by Leslie Mehrhoff, University of Connecticut, Bugwood.org.|
|Figure 4a. Japanese barberry berries. Photo by Kathy Smith, Ohio State University Extension.||Figure 4b. Common barberry berries. Photo by Leslie Mehrhoff, University of Connecticut, Bugwood.org.|
These berries attract birds and other wildlife that eat and disperse the fruit and its seeds, spreading the shrub. These shrubs also spread by branch layering and underground rhizomes, sending up shoots from the roots and root remnants in the soil. This spreading habit can establish thick, hard-to-manage stands of thorny shrubbery that crowd out native plants.
Barberry and Ticks
Ticks are a major public health threat to humans, companion animals, and livestock. Multiple diseases of consequence such as Lyme disease, Rocky Mountain spotted fever, and anaplasmosis can be vectored or transmitted by ticks to their host during feeding. In 2020, two tick species were newly recorded in Ohio. The invasive Asian longhorned tick (Haemaphysalis longicornis) was discovered in Gallia County on a dog, and established populations of the Gulf Coast tick (Amblyomma maculatum) were found in multiple southwestern Ohio counties.
Researchers are exploring the relationship between tick populations and Japanese barberry. Deer ticks, also known as black-legged ticks (Ixodes scapularis), are the primary vectors of Lyme disease to humans, canines, and equines. Reported cases of Lyme disease in Ohio have steadily increased over the past ten years (Ohio Dept. Health 2021). Research conducted by the Connecticut Agricultural Experiment Station, an independent state agency, reported higher populations of deer ticks in areas where Japanese barberry was present than in areas where barberry was managed (Williams et. al. 2017). It is hypothesized that the dense growth of barberry creates microhabitat beneficial to tick survival (Williams et. al. 2017), protects ticks from predators ,and increases tick-to-host contact between the nymphal deer ticks and its primary, first stage host, the white-footed mouse (Linske et al. 2018). A multi-year study (Williams et al. 2017) provides a strong argument for the continued management of invasive Berberis spp as a powerful method to combat tick populations.
Integrated Pest Management
Barberry is very difficult to control. The root system will vigorously resprout and spread. Its thick growth habit and sharp thorns make finding and eradicating early barberry growth critical to avoid prolonged and repeated management.
Early invasions can be managed by pulling small plants by hand or by digging plants out by the root before fruiting. Even after removal, monitoring is highly recommended to spot regrowth from root remnants and new germination from seeds, which can remain viable for up to 9 years in the seedbank (Gucker 2009). Personal protective gear is important as spines are very sharp and can break off under the skin. Mowing is not an effective treatment unless the practice is repeated year after year until the plant no longer has the energy stored to resprout. Mowing in combination with the application of a foliar treatment to resprouts can be effective.
Herbicide treatment is also an option and often necessary when dealing with non-native invasive plants. Constant monitoring of the site and repeated herbicide applications will be necessary to manage and control stands, reaffirming the importance of early detection, eradication, and treatment.
Herbicide Control Methods for Eradicating Barberry
Herbicides applied to the leaf surface is effective for control of barberry. Foliar sprays should be applied late summer into early fall in Ohio. Brush management herbicides such as glyphosate + triclopyr mixtures are the common choice. These are non-selective and can impact surrounding plants and trees, so use caution when targeting the spray. The addition of a surfactant to the chemical mix ensures a better rate of absorption and is more effective than applying the herbicide alone.
Basal bark and cut-stump methods are also an option (see sections on Basal Spraying with Herbicide, and Cut Stump Herbicide Treatment in "F-103 Controlling Non-Native Invasive Plants in Ohio Forests: Privet (Ligustrum spp.)" for more information).
This method applies herbicide directly to a pruned or cut stem. If using an herbicide that is mixed with water, the mixture must be applied to the cut stem immediately after cutting while the wound is fresh. If the herbicide mixture uses an oil carrier (such as diesel fuel, methylated seed oil, etc.—see label for approved options), you can cut the plant and apply later. The oil helps the herbicide absorbs into the stem after healing begins. Keep in mind that herbicide treatment is more effective when it is applied immediately after cutting the plant. Do not apply herbicides when the sap is running, temperatures are below freezing, or when snow is on stems.
This method mixes herbicide with an oil carrier that will penetrate the bark of the plant. It is most effective when the herbicide is sprayed around the entire circumference of the stem, regardless of whether it is a single trunk or a cluster of multiple stems.
Common and Japanese Barberry Herbicides
Some examples of barberry herbicides with triclopyr that are commercially available include:
- Garlon 3A
Home and garden products that control barberry include Brush-B-Gon Poison Ivy, Poison Oak, Brush Killer; and Roundup Brush Killer (Connecticut Invasive Plant Working Group n.d.). Herbicides, like all pesticides, are registered and approved (labeled) for specific uses by the Environmental Protection Agency. Approved uses and application methods are on the pesticide’s label. The herbicides listed in this fact sheet were appropriately labeled for use on Berberis spp at the time of publication. Because pesticide labeling may change at any time, verify that a particular herbicide is still labeled for your intended use. Always follow required personal protection equipment instructions on pesticide labels to prevent injury. The label is the law. You are required to read, follow, and understand the label on all pesticides.
Without management, invasive species such as non-native barberry can outcompete native plants and alter forest ecology. For more information on keeping yourself tick safe, refer to Ohioline publication "HYG-2073 Ticks and Tickborne Disease.”
Kulhanek, A. (2020). Plant Introductions: Meet Invasive Species Common Barberry and Japanese Barberry. Available from: bygl.osu.edu/node/1726.
Templeton, S, Gover, A, Jackson D., and Wurzbacher S. (2020). Japanese Barberry. PennState Extension. Available from: extension.psu.edu/japanese-barberry.
Connecticut Invasive Plant Working Group. n.d. Common Herbicides. Connecticut Invasive Plant Working Group. Accessed August 12, 2021.
Gucker, Corey L. 2009. Berberis vulgaris. Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.
Linske MA, Williams SC, Ward JS, Stafford KC 3rd. 2018. "Indirect Effects of Japanese Barberry Infestations on White-Footed Mice Exposure to Borrelia burgdorferi." Environ Entomol. Volume 47, Issue 4, August 2018: 795–802.
Ohio Department of Health. 2021. Lyme Disease. Zoonotic Disease Program.
USDA ARS (U.S. Department of Agriculture, Agricultural Research Services). 2016. Barberry Situation- Past, Present, Future. St. Paul, MN: Cereal Disease Lab.
Williams, Scott C., Megan A. Linske, and Jeffrey S. Ward. 2017. "Long-Term Effects of Berberis thunbergii (Ranunculales: Berberidaceae) Management on Ixodes scapularis (Acari: Ixodidae) Abundance and Borrelia burgdorferi (Spirochaetales: Spirochaetaceae) Prevalence in Connecticut, USA." Environmental Entomology, Volume 46, Issue 6, December 2017: 1329–1338.