Control of Invasive Non-Native Plants

In the next century, the greatest threat
T housands of plant species
have been brought to North
American in the past three
to our native plants and the wildlife species that centuries. Most are well-behaved,
depend upon them rarely penetrating natural areas.
may well come from other plants.
Several hundred, however, have no
natural controls here, and are able
to out-compete and gradually
displace our native plants, even
deep in forests and undisturbed
Control of Invasive ecosystems.

Variously called alien, introduced,
Non-Native Plants or exotic, these non-natives are
highly invasive.
A Guide For Gardeners
and Homeowners in the
Mid-Atlantic Region Some of these plants were
brought here intentionally, for their
medicinal, ornamental, or food
For more nature habitat information value. Others hid in soil, crop seed,
Visit these helpful websites: or ballast.
A Plant's Home
A Bird's Home Most came from other
A Homesteader's Home continents, but a few have spread
from other parts of the U.S. In each
region, different species are better
adapted and therefore pose a
greater threat.

This guide is for the piedmont and
inner coastal plain regions of
Maryland, northern Virginia, the
District of Columbia, Delaware, and
southeastern Pennsylvania.

Many of the plants in this guide
are popular, even beloved, landscape
plants, but it is now clear that they
pose a threat to our environment.

If you cannot effectively contain
these plants within your property,
by clipping seeds, fruits, or runners,
please consider removing them.

It is a difficult decision, but each
of us has a responsibility not to
damage the local ecosystem that
cleans our air and water, stabilizes
the soil, buffers floods, and provides
food and shelter for innumerable
species besides our own.

© WindStar Wildlife Institute Page 1 A Plant's Home

Each of the non-native plants free. If so, it has no natural Invasive, Non-Native Shrubs
in this guide significantly reduces controls here. Do not plant it Multiflora Rose ( Rosa
the number of plant and animal if it can spread out of the multiflora), formerly recommended
species on any site it invades. garden. for erosion control, hedges, and
wildlife habitat, becomes a huge
When evaluating exotic plants s Does it have the ability to kill shrub that chokes out all other
for your garden, ask these or suppress growth of vegetation and is too dense for
questions: surrounding plants by shading many species of birds to nest in,
them out, chemically poisoning though a few favor it.
s Does it naturalize or self-sow. them, or out-competing them
How far does it spread. Are for food and water. (Norway In shade, it grows up trees like a
the seeds spread by wind or maple, a common landscape vine. It is covered with white
water. tree, is a prime example.) If flowers in June. (Our native roses
If so, don‘t plant it unless so, you don’t want it in your have fewer flowers, mostly pink.)
you are prepared to remove all garden anyway!
seeds, every year. Distinguish multiflora by its
This guide lists garden plants size, and by the presence of very
s Is it a wildlife food plant. If the and weeds which are already hard, curved thorns, and a fringed
answer is yes, wildlife will causing significant changes to edge to the leaf stalk.
spread it to woods and natural areas in the Mid-Atlantic.
wetlands. In other words, Control: (1) – pull seedlings, dig
these are plants to avoid. Measures for controlling each out larger plants at least 6" from
Plant natives instead. species are indicated by number, the crown and 6" down; (4) on
e.g., (3), in the text, and explained extensive infestations; (10) or (11).
s Is it a rapidly spreading on page 9.
ground cover. If so, don’t It may remain green in winter, so
plant it adjacent to open The suggested alternatives are herbicide may be applied when
space. native plants, well adapted and other plants are dormant. For
needing little care, attractive to foliar applications, mix Rodeo with
s Is it low maintenance – hardy, birds and butterflies, and an extra sticker-spreader, or use
tolerant of drought or important part of the food web Roundup Sure Shot Foam on small
flooding, shade-tolerant, pest for our indigenous species. plants.

Recommended Native Shrubs
Spicebush ( Lindera benzoin), which is covered with tiny yellow flowers
in March, is our most common native shrub. It needs rich soil, as
does Strawberry bush (Euonymus americanus).

Maple-leaf viburnum ( Viburnum acerifolium) is suited to dry shade
and thinner soil, while the arrowwoods (Viburnum dentatum, V.
recognitum, V. nudum) grow in moist soil.

Wild hydrangea ( Hydrangea arborescens), parent of some cultivated
varieties, is a somewhat vining shrub.

Highbush blueberry (Vaccinium corymbosum, the parent of cultivated
blueberries) and Lowbush blueberry (V. vacillans ) need very acidic soil.
They tolerate shade but fruit best in sun. Both turn red in fall.
Multiflora Rose


Bush Honeysuckles ( Lonicera
spp.), including Belle, Amur,
Morrow’s and Tatarian
honeysuckle. (In our region,
assume that any honeysuckle is
exotic unless it is a scarlet-
flowered vine.)

Bush honeysuckles create
denser shade than native shrubs,
reducing plant diversity and
eliminating nest sites for many
forest interior species.

Control: (2) on ornamentals; (1); Garlic Mustard
on shady sites only, brush cut in
early spring and again in early fall
(3); (4) during the growing The Most Invasive prevent it from setting seed (3).
season; (7); or (10) late in the Non-Native Weeds Use glyphosate (11) or herbicidal
growing season. Garlic Mustard (Alliaria soap (less effective) on large
petiolata, A. officinalis), a white- infestations. Follow-up with (5) in
flowered biennial with rough, spring.
Other Ornamental Shrubs scalloped leaves (kidney, heart- or
Japanese Spiraea (Spiraea arrow-shaped), recognizable by Mile-a-minute Vine, Devil’s Tail
japonica). Control: (1); (2); (3), the smell of garlic and taste of Tearthumb ( Polygonum
(7), (10), or (11). mustard when its leaves are perfolatum), a rapidly growing
crushed. annual vine with triangular leaves,
Privet (all Ligustrum species). barbed stems, and turquoise
Control: (1); (7) or (10); or trim off Control: Pull before it flowers in berries in August which are spread
all flowers. Do not cut back or spring (10) removing crown and by birds. It quickly covers and
mow. roots. Tamp down soil afterwards. shades out herbaceous plants.
Once it has flowered, cut (2),
Burning Bush, Winged being careful not to scatter seed, Control: same as for stilt grass.
Euonymus, Winged Wahoo, then bag and burn or seed to the
(Euonymus alatus), identified by landfill. (11) may be appropriate in Japanese Perilla, Beefsteak
wide, corky wings on the branches. some settings. Plant ( Perilla frutescens ). Sold as
a salad plant, this member of the
There is another species called Japanese or Vietnamese Stilt mint family is extremely invasive by
Burning bush, E. atropurpureus, Grass, Eulalia (Microstegium wind-borne seeds. Recognize it by
which is indigenous to the vimineum) can be identified by its the odd odor, supposedly like raw
Appalachians, and a piedmont lime-green color and a line of beef, when you rub it.
euonymus called Strawberry bush silvery hairs down the middle of
(E. americanus ). the 2-3" long blade. It tolerates Control: (1); (2); (10) or (11).
sun or dense shade and quickly
Control: (1); (7) or (10); or trim invades areas left bare or Spotted Knapweed ( Centaurea
off all flowers. disturbed by tilling or flooding. maculosa) a biennial with thistle-
like flowers.
Japanese Barberry (Berberis Control: Easily pulled in early to
thunbergii), red and green mid-summer (1) – be sure to pull Canada Thistle, Bull Thistle
varieties. before it goes to seed. If seeds ( Cirsium arvense, C. Vulgare ).
have formed, bag and burn or send Exotic thistles are far more
Control: (1); (7) or (10); or trim to landfill. Mowing weekly, or when common than native ones. If you
off all flowers. it has just begun to flower may cannot identify the species, it is


Invasive Wetland Plants used, cut annually in late July to has spread from gardens to
A number of ornamental plants reduce spread. carpet our flood plains with small
once recommended for water yellow flowers in spring.
gardens or moist garden soil have Giant Reed (Arundo donax )
spread to our riverbanks, flood chokes waterways from Virginia It comes up in winter, giving it a
plains, and wetlands. south. It can grow 20' tall. head start over most native
spring wildflowers.
They are extremely difficult to Control: same as for Phragmites
eradicate once established – up to or mow several times a season. Control: it is not yet known
10 years of repeated treatment whether digging is effective – the
may be needed to remove Purple Japanese Knotweed, Mexican small reproductive corms break off
loosestrife or Phragmites. These Bamboo ( Polygonum cuspidatum) very easily.
plants propagate by seed and by can grow in shade. The stems have
fleshy root parts which break off knotty joints, reminiscent of Try digging (1) before the plants
easily. Both are spread by water, bamboo. It grows 6-10' tall and flower. Otherwise, use Rodeo (10 or
feet (human, animal, bird), and has large pointed oval or 11), preferably in February to
tires, including those of mowers. triangular leaves. protect native plants, frogs, and
They are also found in dredge spoil, salamanders which become active
fill dirt, and compost. it is not Control: cut at least three in March.
clear whether seeds may be times each growing season and/or
transported by wind. treat with Rodeo (10) or (11). In
gardens, heavy mulch or dense Recommended Native Wetland
Do not plant exotic water shade may kill it. Plants for Water Gardens
garden plants unless they are
not hardy, and never dump plants Purple Loosestrife (Lythrum s Turtlehead
from fish tanks or water gardens salicaria, L. virgatum), a (Chelone glabra)
into toilets, storm drains, lakes, handsome garden plant, has tall
or streams. spikes of magenta flowers over a s Lizard’s tail
long bloom season. (Saururus cernuus)
Common Reed (Phragmites
australis,formerly P. communis) Often marketed as sterile, it is s Cardinal flower
looks like a tall ornamental grass at best self-sterile, i.e., it can be (Lobelia cardinalis)
with lovely plumes, usually white or pollinated by plants you may not
tan. be aware of, growing nearby. s New York ironweed
(Vernonia noveboracencis)
Although the species is A single plant can produce up to
indigenous, a particularly a million seeds. Like Phragmites, it s Blue flag (Iris versicolor)
aggressive strain, probably chokes out all competitors and
introduced or a hybrid, has has taken over millions of acres of s Virginia bluebells
escaped from natural controls and wetland in the U.S. (Mertensia virginica)
taken over many formerly diverse
wetlands. It is also seen in Control: initial infestations may s Wild blue phlox
roadside ditches. be hand-pulled (1) before flowering (Phlox divaricata)
(do not dig). Bag and burn or send
Control: (10) or (11), using Rodeo to the landfill. Otherwise, use s Arrowhead
when the plant is flowering. If Rodeo (10) or (11) when plants (Sagittaria latifolia)
possible, follow-up with a begin to bloom (they continue to
controlled burn of the dead plants, flower while setting seed). Expect s Pickerelweed
to allow native plants to return. to re-treat for several years until (Pontederia cordata)
the seed bank is exhausted.
Do not dig Phragmites – the s Also use native reeds, rushes,
roots will break, re-sprout, and Lesser Celandine, Celandine and sedges.
spread. If herbicide cannot be Buttercup ( Ranunculus ficaria)


Small to Medium Invasive, Flowering Fruit Trees – these
Non-Native Trees displace our native fruit trees: Recommended Small Native
Empress Tree, Princess Tree Cherry, edible and ornamental Ornamental Trees
(Paulownia tomentosa) – large (Prunus avium, P. cerasus , Serviceberry ( Amelanchier spp.),
panicles of lavender flowers, like Japanese species and hybrids). Fringetree ( Chionanthus
upside-down wisteria, identify this Pear, Bradford and other virginicus ), Black haw (Viburnum
tree in spring; the large brown Ornamental Pears ( Pyrus prunifolium), and Red
seed capsules remain all year. calleryana ) – self-sterile but can chokeberry ( Aronia arbutifolia)
pollinate other cultivars, now are beautiful flowering trees
Winged seeds allow it to spread spreading rapidly from street that also produce fruit for
deep into undeveloped areas, plantings. birds.
though it needs some sunlight and
is most common along trails and White Mulberry (Morus alba ) –
waterways. It grows very rapidly the fruits may be white, purple, or
and sprouts readily from roots black; leaves are lobed. Our under which nothing else grows. Its
and cut stumps. delicious native red mulberry, which small oval leaves have a single
has very large, usually unlobed tooth.
Control: (1) – seedlings and leaves, is dying out from a root
small saplings only; (7), (8), (9), disease carried by white mulberry. Control: (1); (7), (8), (9), or (10).
or (10) – use 50% solution, any
time the ground is not frozen; (11) Control of flowering/fruit trees: Russian Olive, Autumn Olive
on re-growth and small trees. (1); (7) or (10); (8) if very large; or ( Eleagnus angustifolium, E.
if grown for harvest, protect fruit umbellata ) – formerly
Mimosa ( Albizia julibrissin) has from birds with netting or recommended for erosion control
rather garish pink flowers in hardware cloth. and wildlife value, these have
summer and feathery compound proved highly invasive and diminish
leaves. It spreads slowly by wind- Siberian Elm ( Ulmus pumila ), a the overall quality of wildlife
borne seed pods, or in water or fill- fast-growing medium-height tree habitat.
dirt. It re-sprouts when cut or also sold for hedges, displaces our
burned. Needs some sunlight. native elms, which are already Control: (1) – up to 4" diameter
under pressure from Dutch elm trunks; (7) or (10) or bury stump.
Control: (1); (7), (8), (9), or (10). disease. It forms dense thickets Do not mow or burn.

Recommended Native Trees For Hedges Invasive Ornamental Grasses
American hazel nut (Corylus americana) makes an excellent hedge. Often promoted as native
In damp soils, Slippery elm (Ulmus rubra) is a good substitute for plants, most ornamental grasses
Siberian elm. come from outside our region.
Once established, they are
On sunny, dry sites, Staghorn sumac or Shining sumac (Rhus extremely tenacious. They are now
typhina, R. copallina) form thickets; keep suckers in check by mowing. spreading into our meadows.

So far, Pampas grass
Recommended Native Shade Trees ( Cortaderia selloana and C.
White oak (Quercus alba), Northern or Southern red oak (Q. rubra, jubata), Japanese silver grass
Q. Falcata), and Mockernut hickory ( Carya tomentosa) are widely ( Miscanthus sinensis ), and Reed
adapted shade trees. canary grass (Phalaris
arundinacea) have been the most
Other oaks and hickories are suited to very dry, wet, or steep sites. invasive.
Tupelo, also called Black or Sour gum ( Nyssa sylvatic) has brilliant
red fall foliage and small fruits eaten by birds. Control: (1); (2); or (11), using
additional sticker-spreader.


Medium to Tall or March to protect surrounding Recommended Native Grasses
Invasive, Non-Native Trees plants). Use maximum strength Native grasses usually grow in
Norway Maple (Acer specified on label for all herbicide small clumps, in a mix of several
platanoides) has large leaves applications on Ailanthus. species.
similar to sugar maple. Break a
leaf or stalk – a drop of white Glyphosate is not effective Tall ones include Indian grass
sap will show if it is Norway against Ailanthus. (Sorghastrum nutans ), Big
maple. bluestem ( Andropogon gerardii),
Sawtooth Oak ( Quercus Purple top ( Triodi flava), and, on
Fall foliage is yellow. acutissima ) – often recommended the coastal plain, Switch grass
(Exceptions: cultivars such as for wildlife, this Asian tree has (Panicum virgatum).
“Crimson King," which have red spread into our region from
leaves in spring or summer, may forestry plants, displacing Small to medium grasses
have red autumn leaves.) The indigenous forest trees. include Little bluestem
leaves turn color late, usually in (Schizachyrium scoparium),
November. Control: (1); (7), (8), (9), or (10); Bottlebrush ( Hystrix patula),
(11) on small trees and re-growth. and Wild oats ( Uniola latifolia).
This tree suppresses growth
of grass, garden plants, and
forest understory beneath it, at
least as far as the drip-line.
This Guide was compiled for the Maryland Native Plant Society by
Our mixed deciduous forests Louisa Thompson, Master Gardener Consultant, Maryland Cooperative
will give way to pure stands of Extension, March, 1999.
Norway maple in the next
century unless we control its Sources include:
spread now.
s “Exotic Plants," by Gene Cooley, MD Natural Heritage Program
Control: (1); (7), (8), (9), or
(10); (11) in mid-October to early
s “Invasive Alien Plant Species of Virginia," by the Virginia Native
November, before the leaves turn
Plant Society and the VA Division of Natural Heritage
color.
s “Plant Invaders of Parks and Natural Areas," by the NPCI Alien
Tree of Heaven ( ilanthus
A Plant Working Group
altissima ), known from A Tree
Grows in Brooklyn incredibly
, is
“Invasive Exotic Pest Plants in Tennessee," by the Tennessee Exotic
s
tough and can grow in the
Pest Plant Council
poorest conditions.
s “Element Stewardship Abstracts" of The Nature Conservancy
It produces huge quantities of
wind-borne seeds, grows rapidly,
s “Invasive Plants: Weeds of the Global Garden," by John M. Randall
and secretes a toxin that kills
and Janet Marinelli, 1996, Brooklyn Botanic Gardens Book Club
other plants. Once established,
this tree cannot be removed by
s The Monsanto web-page ( www
.monsanto .com).
mechanical means alone.
The author would like to thank Rod Simmons, Jil Swearingen, Susan
Control: (1) – seedlings only.
Rudy, Susan Salmons, Philip Pannill, Marc Imlay, Marion deGroff, Jane
Herbicide – use Garlon 3a(9)
Baldwin, Graham Egerton, and Ray Bosmans for their comments.
with no more than a 1" gap
between cuts, or (10); plus (11) on
Control of invasive exotic plants is a new endeavor; the
re-growth. Or paint bottom 12" of
recommendations given here may not have been fully tested.
bark with Garlon 4 (in February


Invasive, Non-Native Vines bright orange seed capsules in Control: clip off flowers or fruits
All of these vines shade out the clusters all along the stem, while if any are seen (2), and (1) pull
shrubs and young trees of the the native species bears them only any seedlings. To eradicate ivy
forest understory, eventually killing at the branch tips. climbing trees, cut stems as high
them, and changing the open above ground as you can reach,
structure of the forest into a Control: (2); keep ornamental then pull down and paint lower
dense tangle. Do not plant next to plants cut back, remove all fruits portion of stems and foliage with
open space. as soon as they open, and bag or Garlon 3a (10), taking care not to
burn fruits; to eradicate use wet the tree bark. Ground cover:
Kudzu (Pueraria lobata), the vine Garlon 3a (10). pull up as much as you can, dig
that smothered the South, is now out the roots as well as you can,
spreading through the Northeast Porcelain Berry (Ampelopsis and repeat until it no longer re-
and Midwest. It grows extremely brevipedunculata) has small, hard sprouts; or treat re-growth with
rapidly both above and below fruits in a loose, flat cluster that Garlon 3a.
ground, and can pull down trees. turn from white to yellow, lilac,
green, and finally a beautiful Wintercreeper ( Euonymus
Control: small patches may be turquoise blue. fortunei). Control: same as for
eliminated by repeated weeding (1), English Ivy, but Garlon is not
mowing (2), or grazing; established Control: (1) before fruits appear; effective; glyphosate mixed with
infestations can only be controlled keep ornamental plants cut back, extra sticker-spreader may be.
with herbicide (10) or (11) – expect and bag or burn fruits before they
re-growth, but wait a full year and ripen; to eradicate use Garlon 3a Vinca, Periwinkle ( Vinca minor).
re-treat in the third year. Herbicide (10). Control: with persistence, you can
is most effective in early fall. dig out vinca (1); plan to remove
Controlled burning (4) of the dead English Ivy (Hedera helix) grows re-growth. If digging is not
plants the following spring allows up trees and can eventually pull feasible, cut to the ground and
native vegetation to return. them down. It spreads along the treat re-growth with glyphosate
ground and occasionally by fruits. (11).
Japanese Honeysuckle ( Lonicera
japonica), including Hall’s
honeysuckle is a rampant grower
that spirals around trees, often Recommended Native Ornamental Vines
strangling them.
American bittersweet (Celastrus scandens) has been almost
Control: (1); (3); (10); (11) in fall completely displaced by the Asian species. To preserve it, give it
or early spring when native preference, except where its exotic counterpart is present, because
vegetation is dormant. Plan to re- the two hybridize.
treat repeatedly.
Trumpet honeysuckle ( Lonicera sempervirens a semi-evergreen
),
Wisteria, Chinese and Japanese twining shrub with tubular red flowers attractive to hummingbirds, is
(Wisteria sinensis, W. Floribunda) uncommon but indigenous to the piedmont.
both become heavy, woody vines
that can pull down a large tree. Native wisteria ( Wisteria frutescens ), much less aggressive than the
introduced ones, can be grown from Maryland south.
Control: (1); cut back and
deadhead ornamental plants (2); Trumpet vine ( Campsis radicans ) has dramatic flowers attractive to
(10). hummingbirds, and Virginia creeper ( Parthenocissus quinquefolia has)
spectacular red fall foliage, but be aware that both are aggressive
Oriental Bittersweet ( Celastrus growers.
orbiculatus) has almost
completely displaced American Native grapes ( Vitis spp. ) provide an enormous amount of food for
bittersweet ( C. scandens ). The birds but are aggressive and not ornamental.
Asian plant has its flowers and


Invasive Non-Vining Ground Covers Control: (1) (difficult); (2); (6); Note on Herbicides
Crown Vetch ( Coronilla varia) (11). The Maryland Native Plant
has striking pink flowers. Its bare Society strongly recommends
woody stems are unattractive in Indian Strawberry ( Duchesnea non-chemical methods of
winter. Often planted along indica). From India, this shade- control wherever feasible.
highways, its seeds spread tolerant ground cover spreads by However, for large infestations,
invasively. fruit and runners. and for a few plants, non-
chemical methods are
Control: (1); (10) or (11). Control: (1), taking care to inadequate.
remove each crown; (6).
Mints, including Spearmint Applied carefully to avoid non-
(Mentha spicata), Ground Ivy, Gill- Running Bamboos (many species target plants, glyphosate is the
Over-the-Ground, Creeping Charlie and genera; Phyllostachys, least environmentally damaging
(Glechoma hederacea), Henbit Bambusa, and Pseudosasaare the herbicide in most cases.
(Lamium amplexicaule), and Purple most destructive). Many bamboos
Dead Nettle ( L. purpureum), send runners great distances, Roundup contains a stronger
spread by wind-borne seed as well under pavement and edging. concentration of glyphosate
as by runners. than Kleen-Up. Both contain a
Once established, they form petroleum-based sticker-
They grow in sun and shade and impenetrable thickets that are spreader.
are common lawn weeds which have almost impossible to eradicate.
spread to woods and wetlands. Rodeo, the glyphosate
Recognize mints by square stems Plant bamboos only in formulation for wetlands, does
and a minty smell when crushed. containers, never in open soil. not contain any sticker-
Prevent from spreading out spreader and thus is safer for
Plant culinary and ornamental drainage holes. the environment.
mints in containers; prevent from
spreading out drainage holes or Control: (1) – an enormous job; The smallest size of Rodeo
over the top. (10) or (11). available is one quart of
concentrate, obtainable from
Recommended Native Ground Covers farm supply store for about
Evergreen: Golden ragwort (Senecio aureus) and green-and-gold $60. Add food coloring for
(Chrysogonum virginianum) have showy yellow flowers in spring and visibility, and a soap-based
grow in moist shade. Wild stonecrop (Sedum ternatum) has lacy white sticker such as Cide-Kick.
flowers; it grows in thin, rocky soil in light shade. Moss phlox (Phlox
subulata), the familiar landscape plant, has a looser form in the wild, For small applications,
and usually has white flowers; it tolerates very poor soil but needs another choice is Roundup Sure
good drainage. Shot Foam, easier to see and
control than liquid Roundup.
Semi-evergreen: Allegheny spurge (Pachytsandra procumbens) is
indigenous to the mountains but will grow here. It looks much like its Glyphosate is ineffective on
Japanese cousin. some plants; for these,
triclopyr (Garlon), a stump and
Deciduous: Wild ginger (Asarum canadense) has kidney-shaped brush killer, may be indicated or
leaves that seem to sparkle in spring. Not a culinary plant, its roots Crossbow, which will not kill
do have a gingery scent. it needs moist shade. grass.

When using herbicides, read
Recommended Alternatives to Bamboo the entire label and observe all
Giant cane (Arundinaria gigantea), a well-behaved native bamboo, is precautions listed, including
indigenous to damp woods and swamps on the coastal plain. proper disposal. If in doubt, call
Elsewhere, use native grasses or shrubs. your state Extension Service.


Control Measures
(1) Pull seedlings and small or shallow-rooted plants when soil is
moist. Dig out larger plants, including the root systems. Use a
spading fork or weed wrench for trees or shrubs.

(2) To prevent spread of seeds of desirable ornamental plants, cut off
spent flowers (“deadhead") or cut off seeds or fruits before they
ripen. Bag, and burn or send to the landfill.
(3) Mow or cut back at least three times a season to deplete plants’
store of nutrients, reduce seed formation, and kill or minimize spread
of plants. If necessary, repeat each year.

(4) Controlled burning during the spring, repeated over several years,
allows native vegetation to compete more effectively with the exotic.
This may require a permit. Spot treatment with glyphosate in the
late fall can be used to make this method more effective.

(5) Use a corn-based pre-emergence herbicide on annual weeds. This
product is also an organic fertilizer, i.e., it can stimulate growth of
existing plants, including weeds, so it is appropriate for lawns and
gardens but may not be appropriate in woodlands.

(6) In lawns, spot treat with broad-leaf weed killer. Good lawn-care
practices (test soil – use lime and fertilizer only when soil test shows
a need; mow high and frequently – leave clippings on lawn) reduce
weed infestations.

(7) Cut down the tree. Grind out the stump, or clip off re-growth.

(8) Girdle tree – cut through the bark and growing layer (cambium) all
around the trunk, about 6" above the ground. Girdling is most
effective in spring when the sap is rising, and from middle to late
summer when the tree is sending down food to the roots. Clip off re-
growth.

(9) Hack and squirt – hack a hole (several holes in larger trees) WindStar Wildlife Institute is a
downward into the growing layer, and squirt in glyphosate (or national, non-profit, conservation
triclopyr if recommended in text above). Follow label directions for organization whose mission is to
Injection and Frill Applications. This is most effective from middle to help individuals and families
late summer. Clip off any re-growth or paint with glyphosate. establish or improve the wildlife
habitat on their properties.
(10) Cut down, and paint the cut stem or stump with glyphosate (or
triclopyr if specified above). Follow label directions for Cut Stump For more information or
Application. Clip off re-growth or paint with glyphosate. (See Note on for the name of a Master Wildlife
Herbicides.) Habitat Naturalist in your area,
please contact:
(11) Paint foliage with glyphosate herbicide (see Note on Herbicides). Use
an envelope dauber (small sponge-topped bottle), following label
WindStar Wildlife Institute
directions for “wiper" method. Add a drop of food color for visibility.
Or use a foam spray. Avoid dripping on non-target plants, because
glyphosate kills most plants except moss. If it rolls off waxy or grass- E-mail: wildlife@windstar.org
like foliage, use additional sticker-spreader. Deciduous trees, shrubs, http://www.windstar.org
and perennials move nutrients down to the roots in late summer.
Glyphosate is particularly effective at this time and when flowering
plants are in bloom. Several invasive exotics retain their foliage after
native plants have lost theirs, and resume growth earlier in spring Photography by
than most natives. This allows you to treat them without harming Catherine Gilleland, Maryland
the natives. However, the plant must be growing for the herbicide to Master Wildlife Habitat Naturalist
work, and more may be needed in cold weather because growth is
slower.


Control of Invasive Non-Native Plants

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Control of Invasive Non-Native Plants