![](media/image1.png){width="2.5in" height="0.5680555555555555in"}

Pest Management -- Invasive Plant Control

Buckthorns -- VT Class B Noxious Weeds

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

![](media/image2.jpeg){width="3.2444444444444445in"
height="2.433333333333333in"}
![](media/image3.jpeg){width="3.2527777777777778in"
height="2.4430555555555555in"} **Common Buckthorn** (***Rhamnus
cathartica L.)* Glossy Buckthorn** (***Frangula alnus Mill.)***

**Buckthorns**

The buckthorns are native to Eurasia. They were probably introduced to
the US before 1800 but did not become widespread until the early 1900s.
They are now found throughout much of the central and northern United
States and into Canada.

Common and glossy buckthorns are shrubs or small trees that readily
invade natural areas, establishing dense, even-aged thickets which crowd
or shade out native plants. The buckthorns reproduce sexually by seed.
Both buckthorns produce fruits that are readily eaten, and thus seeds
are spread by wildlife. Both buckthorns have lenticels (raised corky
areas) on the bark and the inner bark is yellow.

Common buckthorn has dull green, minutely toothed, oblong leaves that
are opposite or nearly so on the stem. Leaves have 3-4 pairs of veins
which curve upward toward the tip. Branch stems end in small thorns that
appear between the last pair of buds. Fragrant flowers with four
greenish-yellow petals develop into black fruit (3-4 seeds) that may
persist well into winter.

Glossy buckthorn has thin, alternate glossy leaves which are oblong to
elliptical with more than 5 pairs of veins and with smooth or wavy
margins. Buds are rust-colored and naked. Five parted, yellowish-green
flowers ripen from red to black (2-3 seeds).

Buckthorns 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**

The native shrub Alderleaf Buckthorn (Rhamnus alnifolia L'Her) has
alternate leaves with 8-9 pairs of veins and toothed margins. The leaf
surface is puckered (like seer sucker fabric). The buds are scaly (not
naked) but lack thorn tips of common buckthorn.

Chokecherry (Prunus virginiana) is a common native shrub of hedgerows
which has egg-shaped, alternate leaves that are finely and sharply
toothed. Five parted white flowers are borne on dense, cylindrical
racemes.

**Control**

As with all invasive species, buckthorns in natural areas are most
effectively controlled by recognizing their appearance early and
removing isolated plants before they begin to produce seed. With large
infestations, the largest seed-producing plants should be removed first.

Manual, mechanical and chemical methods are all useful to varying
degrees in controlling buckthorns. 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 buckthorn*.*

**Mechanical Control**

Mechanical controls include grubbing or pulling seedlings and mature
shrubs, and repeated clipping of shrubs. Mechanical management requires
a commitment to cut or pull plants at least twice a year for a period of
three to five years. Cutting alone has met with limited success and may
lead to vigorous re-sprouting. Grubbing or pulling by hand (using a Weed
Wrench or a similar tool) is appropriate for small populations or where
herbicides cannot be used.

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**

Burning has met with mixed results and does not show great promise.
Burns should only be used in fire-adapted plant communities of which
there are very few in Vermont. It is generally difficult to burn in
dense buckthorn stands as the understory is typically well-shaded,
allowing little fuel build-up. Be aware of the effects on non-target
vegetation.

**Chemical Control**

Chemical control methods are best done during the fall when most native
plants are dormant yet buckthorns are still actively growing. This
lessens the risk of affecting nontarget plants. The buckthorns\' 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. Do not cut the stem at ground level. 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^**. 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^**. The treatment should be applied to the
foliage late in the growing season. 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**^5^**.
This mixture is also applicable to frill applications where herbicide is
applied into the cambial layer of fresh cuts on the tree trunk**^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 buckthorns will spread
by seeds.

**Information and Recommendations compiled from:**

-   The Nature Conservancy - Element Stewardship Abstract (and
    references therein)

-   Invasive Plant Atlas of New England (IPANE)

-   Vermont Invasive Exotic Plant Fact Sheets

-   CT NRCS Invasive Species ID Sheets

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

-   Alien Plant Invaders of Natural Areas (NPS)

-   Newcomb's Wildflower Guide