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Pest Management -- Invasive Plant Control

Barberries - VT Watch List

***Conservation Practice Job Sheet VT-595***

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**Japanese Barberry (*Berberis thunbergii)* Common Barberry**
(***Berberis vulgaris)***

**Barberries**

Japanese and common barberries are native to Eurasia. Japanese barberry,
the more common species, poses a significant threat to natural areas due
to its popularity as a landscape shrub, ability to tolerate full shade,
and the dispersal of its prolific seeds by birds. Common barberry is
found sporadically in New England, usually establishing in pastures,
open-canopied forests, and sometimes along roads.

Japanese barberry forms dense stands in natural habitats including
woodlands, wetlands, and pastures, and alters soil pH, nitrogen levels,
and biological activity in the soil. Reproduction is primarily through
prolific seeds (high germination rate) although there are also reports
of sprouting from roots as well as vegetative layering. Seeds are spread
by birds and mammals.

The barberries are compact, spiny shrubs that commonly grow from two to
three feet tall but may reach eight feet with yellow-colored inner bark.
Japanese barberry has alternate and entire (smooth margins) leaves with
small (\<1/2" wide, 6 petals) yellow flowers growing alone or in umbels
(flower stems growing from single point) with single spines. Common
barberry has alternate leaves with bristle-toothed margins and spines
are typically in groups of three. It has small yellow flowers in a
raceme (branching off a main flower stalk). See pictures. The bright red
berries persist after leaf off into winter.

Barberries generally leaf-out earlier and retain their leaves longer
than many native shrubs. This trait, shared by many invasive shrubs,
gives them a competitive advantage over native plants but also allows
landowners to easily locate the invasive shrubs and determine their
extent on a property.

**Similar Natives**

There are no native barberries in New England.

**Control**

As with all invasive species, barberry is most effectively controlled by
recognizing their appearance early and removing isolated plants before
they begin to produce seed.

Manual, mechanical and chemical methods are all useful to varying
degrees in controlling barberry. Removing or killing plants will provide
increased light at the site which may lead to a surge of seedlings in
the following year. Prepare to monitor and control these outbreaks.

**Biological Control**

There are no known biological controls of barberry*.*

**Mechanical Control**

Mechanical controls include grubbing or pulling seedlings and mature
shrubs, and repeated clipping of shrubs. Repeated mowing or cutting will
control the spread of Japanese barberry but will not eradicate it. Stems
should be cut at least once per growing season as close to ground level
as possible. Hand-cutting of established clumps is difficult and time
consuming due to the long arching stems and prolific thorns. Grubbing or
pulling by hand (using a Weed Wrench or a similar tool) is appropriate
for small populations or where herbicides cannot be used. Barberry has
shallow roots so small plants may be pulled relatively easily when the
soil is moist. Because barberry can re-sprout from root fragments
remaining in soil, thorough removal of root portions is important.
Manual control works well but may need to be combined with chemical in
large or persistent infestations.

Because disturbed, open soil can support rapid re-invasion, managers
must monitor their efforts at least once per year and repeat control
measures as needed. Limit soil disturbance whenever possible. Winter
clipping should be avoided as it encourages vigorous re-sprouting.

**Prescribed Burning**

There is little information about the efficacy of burns.

**Chemical Control**

Chemical control methods are best done during the fall when most native
plants are dormant yet invasive plants are still actively growing. This
lessens the risk of affecting non-target plants. The barberry's green
leaves will provide easy recognition and allow for a thorough treatment
at this time. Winter application of chemicals has proven to be
successful as well, and further lessens the risk of damaging non-target
species.

Glyphosate (brand names Roundup, and for use near waterbodies,
Rodeo**^1^**) is a nonselective herbicide which kills both grasses and
broad-leaved plants while triclopyr**^3^** (brand names Garlon**^1^**,
Pathfinder**^1^**, and others) is a selective herbicide that kills
broad-leaved plants but does little or no harm to grasses.

**Cut Stump Treatments:** For 'cut stump' treatments, horizontally cut
the stem near the ground. Leaving some stem will allow another cut and
application if there is sprouting. Apply a 20-25% solution of glyphosate
or triclopyr**^3^** and water to the stump being sure to cover the
outer, top 20% of the cut stem**^2,\ 4,\ 5^**. Herbicide must be applied
immediately following the cutting. Add dye or food coloring to the
mixture to track treated stumps. This treatment is best applied late in
the growing season when the plant is transporting nutrients to its root
system (August-October).

**Foliar Treatment:** For foliar treatments a 2% solutions of glyphosate
and water can be used**^2,\ 5^**. The treatment should be applied to the
foliage late in the growing season but can be applied early in the
season to minimize non-target impacts. Do not cut down treated plants
for at least a full growing season.

**Basal Bark Method:** This method is effective throughout the year as
long as snow cover does not prevent spraying to the ground level. Apply
a mixture of 25% triclopyr**^3^** and 75% horticultural oil to the basal
parts of the shrub to a height of 12-15 inches from the
ground**^2,\ 5^**. Be sure to treat entire circumference of the stem in
a band at least 12 inches wide. Thorough wetting is necessary for good
control; spray until run-off is noticeable at the ground line. Do not
apply to bark that's wet from heavy dews and rain.

**^1^** -- Class A Restricted Use Herbicides

**^2^** -- From TNC ESA -- Buckthorns

**^3^** -- Greater than 2% Triclopyr herbicide is Class A - restricted
use in Vermont.

**^4^** - Wisconsin DNR Control Manual

**^5^** -- Alien Plant Invaders Fact Sheets

**Important Note**

Mention of specific pesticide products in this document does not
constitute an endorsement. These products are mentioned specifically in
control literature used to create this document.

**Disposal**

Small, pulled shrubs should be hung in trees to prevent re-rooting.
Larger, pulled shrubs may be piled or piled and burned, roots up, to
prevent re-establishment. Cut stems may be piled or piled and burned. If
chipping, do not remove material from the site as barberry will spread
by seeds.

**Information and Recommendations compiled from:**

-   The Nature Conservancy - Fact Sheets (and references therein)

-   Invasive Plant Atlas of New England (IPANE)

-   CT NRCS Invasive Species ID Sheets

-   Wisconsin Manual of Control Recommendations for Ecologically
    Invasive Plants (DNR)

-   Tennessee Exotic Plant Management Manual

-   Alien Plant Invaders of Natural Areas (NPS)