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Bad Neighbors:
How Invasive Plants Threaten Natives
Cassie L. Conner, Coordinator
Sandhills Weed Management Area
Southern Pines, NC
[email protected]
http://www.sandhillswma.org
What is the Sandhills Weed
Management Area?
The Sandhills Weed Management Area (SWMA) is a
cooperative weed management area which the
Midwest Invasive Plant Network defines as:
“…a local organization that integrates all
invasive plant management resources across
jurisdictional boundaries in order to benefit
entire communities.”
This means….
Cooperative Weed Management Areas
• Organizations working together
• Sharing
resources
• Transcending
property
boundaries
How Do Invasives Impact Natives?
They use
limited
resources
such as
space, light,
water and
nutrients
needed by
native plants.
How Do Invasives Impact Natives?
Some actively smother or strangle other
plants.
How Do Invasives Impact Natives?
Some are allelopathic – their roots
exude a chemical that prevents the
germination of the seeds of other
plants. Spring ephemerals are
especially susceptible.
How Do Invasives Impact Natives?
They change the natural biomass
load and nutrient cycle of areas they invade.
How Do Invasives Impact Natives?
They hybridize with native, and
sometimes rare, populations.
Chinese privet – Ligustrum sinense
Species Profile
Growth form: Chinese privet is a shrub or
small tree growing between 5 to 12 feet
Flower: Flowers occur in cone-shaped,
branching clusters two to four inches long
that profusely cover the shrub. The flowers
produce a somewhat disagreeable aroma
Seeds/Fruit: Flowers mature into bluish black,
berry-like fruits.
Leaves: Leaves are evergreen to semideciduous and oppositely arranged on
nodes usually less than one inch apart.
Stems: Chinese privet branches abundantly
and the branches typically arch gently
downward.
Roots: The root system is shallow but
extensive. Suckers are readily produced.
Lowell Urbatsch @ USDA-NRCS PLANTS Database
Chinese Privet Control
Chinese privet is difficult to control because of the huge seedbank
and the need to remove underground parts as well. Small
infestations in the early stages of invasion can be controlled
mechanically by removing the entire plant. Fire is an ineffective
control method. Herbicide application has been shown to be an
effective control method. Foliar spray application of herbicide can
be used on large thickets where damage to nearby species is not an
issue. Cut stump and basal bark treatments are effective as long as
the ground is not frozen.
SWMA recommendations:
• Small plants in loose soil can be pulled as long as entire plant and
root system are removed
• Small plants that cannot be pulled can be treated with a 2%
glyphosate foliar spray
• Large shrubs should have their stems cut and a 20% glyphosate
mixture should be applied to the cut stump
English Ivy – Hedera helix
Species Profile
Growth form: English ivy is an evergreen climbing
vine or groundcover. It can attach itself to almost
any surface and grow 80 feet high. As a
groundcover it can spread 50 feet wide.
Flower: Small, greenish-white flowers appear on
mature plants. They occur in umbrella-like
clusters in the fall.
Seeds/Fruit: A black, berry-like drupe, ¼ inch
across matures in the spring and ripens over
winter.
(Swearingen 2000)
Leaves: Leaves are alternate, simple, dark green, waxy and
somewhat leathery with many recognized leaf forms. The
most common form being a 3 to 5 lobed leaf with a heartshaped base.
Stems: The stems of older vines are known to reach a foot in
diameter. The stems root as they spread outward.
Roots: Small roots grow from the stems and attach to many
things with a glue-like substance.
(VTU 2002)
English Ivy Control
H. helix originates from landscape plantings. To prevent initial introduction,
native alternative vines should be used in plantings. To control established
invasions, the use of herbicides is most effective. Combining the use of
cutting and herbicide application is very effective.
Native vine alternatives: Trumpet Creeper (Campsis radicans), Virginia Creeper
(Parthenocissus quinquefolia), Passionflower Vine (Passiflora lutea),
Dutchman's Pipe (Aristolochia macrophylla), and native Wisteria (Wisteria
frutescens).
SWMA recommendations:
• Small plants in loose soil can be pulled as long as entire plant and root
system are removed
• Small plants that cannot be pulled can be treated with a 2% glyphosate
foliar spray
• Large vines should be cut near the ground and a 20% glyphosate mixture
should be applied to the cut stump
Chinese Silvergrass – Miscanthus sinensis
Species Profile
Growth form: Tall, densely bunched, perennial
grass, 5 to 10 feet (1.5 to 3 m) in height.
Flower: Much branched and drooping terminal
plumed panicles. Silvery to pinkish,
showiest in fall.
Seeds/Fruit: Many loosely plumed panicles in late
summer turning silvery to pinkish in fall.
Leaves: Long-slender upright-to-arching leaves with
whitish upper midveins.
Stems: Upright-to-arching, originating in tufts from
base and unbranched. Covered with overlapping
leaf sheaths until stem appears with flower
plume in late summer.
Roots: Has a a branched, subterranean rhizome
system by which it can reproduce.
Chinese Silvergrass Control
Chinese Silvergrass reproduces primarily through an extensive
underground rhizome system. A piece of its rhizome as small as 4cm can be
used to propagate the plant. It is also known to move into areas that have
been burned or cut. In addition to this, it is highly flammable and can
increase the intensity of a fire as well as to encourage the spread of the fire
when wind picks up burning pieces of its debris. Therefore it is not
recommended that it be treated with fire. Chemical control can be
successful particularly in the fall with repeat applications. A repeated
combination of mowing and chemical control has proven effective.
NPS recommendation:
Large areas of Chinese Silvergrass can be mowed and then allowed to resprout
to the height of 1 ft. Then apply a foliar spray of 2-3% glyphosate mixture.
Garlic Mustard – Alliaria petiolata
Species Profile
Growth form: Alliaria petiolata is an obligate biennial herb.
Seedlings emerge in spring and form basal rosettes by
midsummer. Immature plants overwinter as basal
rosettes. In the spring of the second year the rosettes
(now adult plants) produce flower stalks, set seed, and
subsequently die.
Flower: April to May. Terminal, tight clusters of small white
four-petaled flowers
Seeds/Fruit: Green ripening to tan and papery, exploding
to expel tiny black seeds up to 10ft.
Leaves: Early basal rosette of kidney-shaped
leaves and later alternate heart-shaped to
triangular leaves.
Stems: Erect, slightly ridged, light green,
hairless above and hairy below. One to
several stems from the same rootstock.
Garlic Mustard Control
Garlic Mustard’s success as an invasive is due to it’s ability to produce
an extensive number of seeds. A single plant can produce thousands
of seed that remain viable in the seedbank for at least 5 years. Any
successful control will require a commitment to treat the site at least
annually for several years. Mechanical removal such as pulling, cutting
or mowing before the plant goes to seed can be successful, as can
chemical control if applied before the plant goes to seed.
SWMA recommendations:
•
•
•
•
•
Small infestations should be hand pulled before the plant sets seed.
Larger, accessible sites should be mowed.
Large, hard to access sites should be treated with a foliar application of
2% glyphosate
Plants with flowers or seed capsules should be bagged and removed
from the site to avoid spreading seed.
All management plans should include treatment over multiple years
until the seed bank is exhausted.
Kudzu - Pueraria montana
Species Profile
Growth form: Semi-woody, aggressively
climbing perennial vine that is capable of
growing a foot per day, extending 60 feet a
year, and reaching up to 100 feet in length.
Flower: Sunlit kudzu produces rare blooms of
elongate hanging racemes that contain
clusters of pea-like purple flowers
Seeds/Fruit: Brown, papery, hairy, flat seed
pods that contain three to twelve small,
hard, rounded seeds.
Leaves: Dark green, deciduous leaves are
alternate and pinnately trifoliate
Stems: Thick, rough, bark-covered stems have
long, yellowish brown hairs at the base
Roots: Edible fibrous tubers can grow to over
seven inches wide and six feet long, and
weigh 400 pounds, with each root crown
capable of forming thirty vines.
Kudzu Control
Kudzu should be cut or mowed late in the growing season and the
plant material should be removed from the area and destroyed.
Herbicide should be applied to the cut stems. The type of herbicide
used depends on the landscape and its uses. Burning after the
herbicide has killed the Kudzu may assist native plants in
colonizing the site. This procedure will need to be repeated for 4-10
years.
SWMA Recommendations:
• Cut vines of climbing or trailing kudzu until a root crown is found.
Dig up root crown with a mattock and spray with a 20% glyphosate
solution.
Oriental Bittersweet – Celastrus orbiculatus
Species Profile
Growth form: Deciduous, twining and
climbing woody vine to 60 feet (20 m) in
tree crowns, forming thicket and arbor
infestations.
Flower: Axillary dangling clusters of
inconspicuous yellowish flowers in
spring.
Seeds/Fruit: Green spherical fruit that split
to reveal three-parted showy scarlet
berries in winter.
Leaves: Alternate, elliptic to rounded leaves.
Variable shaped, long tapering tipped when
young becoming larger and round tipped
when mature.
Stems: Woody vine to 4 inches (10 cm)
diameter, twining and arbor forming, with
many alternate drooping branches growing at
angles and eventually becoming straight.
Oriental Bittersweet Control
Oriental Bittersweet is a widespread and prolific invasive due in part to it’s
commercial use by humans. It is particularly difficult to control because of
it’s lack of response to common herbicides like glyphosate. Weekly mowing
can be an effective control, but less frequent mowing will stimulate root
suckering. Manual pulling has been effective on small infestation and a
combination of cutting and herbicide application has been effective in
controlling large populations. If seeds are present on pulled or cut plants,
they should be bagged and removed from the site to prevent further
seedbank establishment.
SWM recommendations:
• Small plants in loose soil can be pulled as long as entire plant and root
system are removed
• Small plants that cannot be pulled can be treated with a 2% tricolpyr foliar
spray
•
Large vines should be cut near the ground and either immediately treated
with a 25% triclopyr solution or allowed to resurge for a month and then
treat the regrowth with a 2% triclopyr foliar spray
Invasive
Native
Oriental Bittersweet vs. American Bittersweet
(Celastrus orbiculatus)
(Celastrus scandens)
• Fast grower
• Slow grower
• Flowers and fruit present • Flowers and fruit present
all along stems
only at the end of stems
• Smaller fruit, 5 or more
seeds
• Larger fruit, 1 or fewer
seeds
• When first leafing out,
the two sides of the leaf
are folded together
• When first leafing out,
the leaf margins are rolled
under like a scroll
American Bittersweet is threatened by Oriental
Bittersweet – hybridization
Invasive
Native
Oriental Bittersweet vs. American Bittersweet
(Celastrus orbiculatus)
(Celastrus scandens)
Oriental Bittersweet –
North Carolina Class C Noxious Weed
• NC has three classes of noxious weeds; A,B and C
• Class A plants are prohibited from being sold,
distributed or moved into or within North Carolina
- includes all federally-listed weeds plus 5 others
• Class B plants are prohibited from being sold,
distributed or moved out of counties under quarantine
- includes 9 species
• Class C plants are prohibited from being moved out of
counties under quarantine, BUT sale and distribution
is allowed
– Oriental Bittersweet is the ONLY plant in Class C
Summer ED/RR Field Team
• An Early Detection/Rapid Response approach
allows land managers to quickly address new
invasive plant problems
• The SWMA Field
Team worked on
six different sites
for four partnership
members
SWMA Website:
http://www.sandhillswma.org
Website Features
• A native plant list with suggestions for
alternatives to invasives
• Species profiles
• Species distribution lists
• Photos for learning identification
• A message board for community interaction
• Links to other invasive management resources
• Past presentation and other outreach material
Benefits of a CWMA
Resource Sharing
Physical Resources
-Tools
- Herbicide
- Equipment
- Storage
Benefits of a CWMA
Resource Sharing
Human Resources
- One coordinator or leadership committee
for all areas
- Expertise of land managers, biologists,
botanists, etc. from all partner
organization
- Field team available for use in all areas
Benefits of a CWMA
Transcending Boundaries
Weeds don’t obey property lines
- Infestations may stretch across
jurisdictional boundaries
- Populations in adjacent areas
may infest high quality area
Benefits of a CWMA
Managing a Large Area
• Assessing new species for Early Detection/Rapid
Response consideration
• Prioritizing control activities
- Examples of high priority sites
 Infestations of new
invasive species with
potential to spread
 Infestations in or near
high quality sites