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Pest Management -- Invasive Plant Control

Shrub Honeysuckles -- VT Class B Noxious Weeds

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

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![](media/image3.jpeg){width="3.2354166666666666in"
height="2.4194444444444443in"} **Morrow\'s honeysuckle (*Lonicera
morrowii)* Tatarian honeysuckle (*Lonicera tatarica)***

**Shrub Honeysuckles**

The exotic shrub honeysuckles are increasingly common throughout much of
the eastern and Midwestern United States and south-central Canada where
they have contributed to reduced species richness and cover of native
herb communities and to reduced tree regeneration in early to
mid-successional forests. Although disturbance of some kind usually
precedes invasion, the exotic shrub honeysuckles are adapted to a wide
variety of habitats. Reproduction is almost entirely by seed. Seed
production and short-term seed viability are consistently high, and
seeds are readily dispersed by birds and, perhaps, small mammals.

Exotic shrub honeysuckles are upright, multi-stemmed, oppositely
branched, deciduous shrubs. The exotic honeysuckles have hollow center
branches when mature (native honeysuckles do not). The opposite leaves
are entire (un-toothed margins) and paired. Axillary flowers (where leaf
is attached to stem) are showy with white, pink, and sometimes aging to
yellow corollas. The fruits of honeysuckles are usually red but can be
yellow, orange or clear and fleshy. The fruits are never blue, black or
white. In flower, exotic shrub honeysuckles can be distinguished from
all native shrub honeysuckles except swamp fly-honeysuckle (*L.
oblongifolia*) by their hirsute (hairy) styles.

The exotic shrub honeysuckles also generally leaf-out earlier and retain
their leaves longer than the native shrub honeysuckles. 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**

Most notable in Vermont are the rare and uncommon fly honeysuckles
Lonicera oblongifolia (S2) and Lonicera villosa (S3) and Lonicera
canadensis which all have solid white piths.

**Control**

The potential for large-scale restoration of unmanaged natural areas
infested with honeysuckle is probably low. Restoration potential for
managed natural areas infested with honeysuckle is probably moderate. If
attacked during the early stages of colonization, the potential for
successful management is high.

Manual, mechanical, environmental/cultural, and chemical methods are all
useful to varying degrees in controlling honeysuckles. 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 honeysuckle.

**Mechanical Control**

Mechanical controls include grubbing or pulling seedlings and mature
shrubs, and repeated clipping of shrubs. Effective mechanical management
requires a commitment to cut or pull plants at least twice a year for a
period of three to five years. Cuttings should be done in the growing
season (spring and fall). Grubbing or pulling by hand (using a Weed
Wrench or a similar tool) is appropriate for small populations or where
herbicides cannot be used.

Any portions of the root system not removed can re-sprout. 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**

Repeated annual prescribed burns during the growing season will top-kill
shrubs and inhibit new shoot production. Because exotic shrub
honeysuckles readily re-sprout, it may be necessary to re-burn every
year or every other year for several years to achieve good control. Be
aware that few plant communities in Vermont are fire-adapted so consider
the effects on non-target vegetation.

**Chemical Control**

Most managers report that treatment with herbicides is necessary for
large shrub honeysuckle populations. Formulations of glyphosate (brand
names Roundup, and for use near waterbodies, Rodeo**^1^**) and
formulations of triclopyr (brand names Garlon**^1^**, Pathfinder**^1^**,
and others), have been used as foliar sprays or cut stump sprays and
paints with varying degrees of success.

Glyphosate is a nonselective herbicide which kills both grasses and
broad-leaved plants while triclopyr 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 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
or triclopyr and water can be used**^2^**. Both glyphosate and triclopyr
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**^2,\ 4^**. 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 -- Bush Honeysuckles

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

^4^ -- Tennessee Exotic Plant Management Manual

**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 honeysuckle will
spread by seeds.

**Information and Recommendations compiled from:**

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

-   Tennessee Exotic Plant Management Manual

-   Invasive Plant Atlas of New England (IPANE)

-   Virginia Natural Heritage Program -- Invasive Plant Fact Sheets

-   Vermont Invasive Exotic Plant Fact Sheets

-   CT NRCS Invasive Species ID Sheets