Barberry, Japanese

Fact SheetBerberis thunbergii

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Common look-alikes:

Identification

Appearance

Berberis thunbergii is a small deciduous shrub from 2-8 feet tall. The thin, grooved branches have thin, straight spines. Berberis thunbergii is very shade-tolerant and can form dense stands which shade out and displace native species.

Foliage

The leaves are up to 1 inch long and paddle-shaped.

Flowers

The pale-yellow flowers occur in drooping clusters of 2-5 and develop in mid-spring to early summer.

Fruit

The berries ripen to a bright red color and are 0.25-0.3 inches long.

Check out the downloadable fact sheet above

The University of Connecticut has released an excellent video series on barberry. 

Part 1: The Trouble with Barberry

Part 2: Controlling Barberry

Part 3: All About Lyme Disease

Biology

ECOLOGICAL THREAT

Barberry forms dense stands in natural habitats including forests, open woodlands, wetlands and meadows. Once established, it displaces native plants and reduces wildlife habitat and forage, increasing pressure on natives by white-tailed deer. It has been found to alter the pH and biological activity of soil. Barberry is also a human health hazard, not only because it has sharp spines, but also because it acts as a nursery for deer ticks, which can transmit Lyme disease.

Origin

Japanese barberry was introduced into the United States as an ornamental plant in 1875. It was promoted as a substitute for European barberry, the latter which was found to be a host for the black stem grain rust. European barberry was originally planted by settlers for hedgerows, dye and jam-making. Japanese barberry is still widely planted for landscaping and hedges.

HABITAT

Forest, forest edge, floodplains, meadows, fields, disturbed areas

Life Cycle

Reproduction is mainly by seed but it can root sprout and layer. Barberry produces a large number of seeds with high germination rates, estimated at up to 90%. Fruits mature from July to October and persist well into the winter. Fruit production varies with light level, but even under very low light levels (4% full sun) some seeds are produced. 

Management Options

This species is Quarantined: Class B Noxious Weed  

Treatment Concerns: 

  • Japanese barberry “leafs out” very early compared to most native vegetation, thus making them easy to detect in early spring.  
  • Other helpful indicators to look for are the yellow-colored inner bark and roots. 
  • Thorns are sharp and irritation may occur at puncture sites. Use caution and wear gloves when handling this plant. 
  • Because of the high risk of spread by seeds, treatments are most effective before the plants go to seed. 
  • Seeds can persist for a few years in the seedbank, so it is beneficial to prevent the plant from setting seed. 
  • Japanese barberry biomass seems to increase the amount of nitrogen in the soil, which encourages new barberry growth and inhibits that of other plants. There is also a correlation between Japanese barberry, soil nitrification, and non-native earthworms 
  • Thorns are sharp, made of silicate, and irritation may occur at puncture sites. Use caution and wear gloves when handling this plant  
  • Japanese barberry has been implicated in the spread of Lyme disease because of the habitat it creates for mice and ticks, who are vectors for the bacteria that causes Lyme disease.  
  • In places with high deer pressure, locally evolved plants are often replaced by Japanese barberry. 

General Guidance

Summary of Mechanical Treatment Options 
  • Mechanical treatment can sometimes cause greater disturbance than if the site was left alone or if another treatment option was utilized. 
  • If pulling or digging, remember that soil disturbance can encourage growth from seed bank.
  • It is beneficial to remove plants before they begin fruiting later in the growing season. 
  • Portions of roots system not removed can re-sprout.  

 

text in a table describing mechanical treatments for Japanese barberry

Summary of Chemical Treatment Options
  •  Be careful not to damage or kill nearby desirable plants when conducting management work.  
  • The label is the law for all pesticides (economic poisons) and uses.  
  • If a treatment for a specific species isn’t listed on a given product, don’t use it. 
  • Product labels may require you to check Endangered Species Protection Bulletins. Learn more about protection bulletins here.  
  • Understand the risk of, and how to avoid, drift.  
  • The timing of some chemical treatments may overlap with when certain plants are flowering, and, in order to protect pollinators, herbicides should not be applied when plants are flowering. To mitigate the risk, consider utilizing an integrated pest management plan, such as cutting the plants to set back flowering time, and then applying pesticides in the lowest effective volume. 
  • Chemical treatments pose a risk to plants, animals, and humans, but can be used in ways that greatly reduce this risk, and provide a solution to otherwise hopeless scenarios. 
  • For questions regarding the appropriate chemical to use for a particular situation, or general information on pesticide safety, ingredients, and more, contact the Vermont Agency of Agriculture, Food & Markets’ Pesticide Program.  
  • For questions about certification and continuing education credit opportunities, contact the Vermont Agency of Agriculture, Food & Markets’ Pesticide Program.  
  • For questions about additional training opportunities, contact the UVM Extension Pesticide Safety Education Program.  
  • Special permits are required to apply herbicides in a wetland. Contact Vermont Department of Environmental Conservation’s Wetlands Section for more information.  
  • Herbicides cannot be applied within 200 feet of a Public Water Source Protection Area unless the Water Supply Division is notified. Call 1-800-823-6500 for more information. Similar requirements may be in place for proximity to private water sources.  
  • Forests that are certified organic or adjacent to organically certified agricultural lands may carry restrictions regarding chemical application. Check with the Northeast Organic Farming Agency of Vermont for more information.  
  • The National Pesticide Information Center provides objective, science-based information about pesticides. Check out their website for more information or call 1-800-858-7378. 

text in a table describing chemical treatments for Japanese barberry

Biocontrol
  • There are no formal biocontrols for Japanese barberry. A North American moth (Coryphista meadii) has been noted as causing extensive defoliation of Japanese barberry in Michigan, but more needs to be learned to know if it could be considered an effective biocontrol.