Download The Northeastern Area Invasive Forest Plant Species Project

The Northeastern Area Invasive
Forest Plant Species Project
Guide to the Invasive Plant Control
Demonstration Plots
Prepared by:
Ellsworth Land Management, LLC
Somerville, MA
Table of Contents
Project Overview..................................................................................................................... 2
Invasive Plant Ecology............................................................................................................ 2
Plant traits ............................................................................................................................. 2
Disturbance history ............................................................................................................... 3
Planning Control and Restoration ........................................................................................ 4
Define Objectives and Assess Resources ............................................................................. 4
Prioritizing Sites.................................................................................................................... 5
Who will do the Work: Volunteers or Professionals? .......................................................... 5
Control Methods ..................................................................................................................... 6
Mechanical............................................................................................................................ 6
Herbicides ............................................................................................................................. 7
Application methods ......................................................................................................... 7
Foliar spray .................................................................................................................. 8
Cut-stump...................................................................................................................... 8
Basal spray.................................................................................................................... 9
Reducing non-target kill ................................................................................................... 9
Restoration/Replanting......................................................................................................... 10
Guide to Demonstration Plots.............................................................................................. 11
Site #1: Asiatic bittersweet control site ........................................................................... 11
Site #2: Honeysuckle control site ..................................................................................... 13
Site #3: Glossy buckthorn control site ............................................................................ 15
Site #4: Japanese barberry control site........................................................................... 16
Common Invasive Species in New England Forests .......................................................... 18
Asiatic bittersweet (Celastrus orbiculatus) ...................................................................... 18
Japanese barberry (Berberis thunbergii) ........................................................................ 19
Shrub honeysuckcle (Lonicera spp.) ................................................................................ 20
Winged euonymus/Burning bush (Euonymus alata)...................................................... 20
Japanese knotweed (Polygonum cuspidatum)................................................................. 21
Multiflora rose (Rosa multiflora) ..................................................................................... 21
Autumn olive (Eleaganus umbellata)............................................................................... 22
Common barberry (Berberis vulgaris) ............................................................................ 23
Glossy buckthorn (Frangula alnus)................................................................................. 23
Common buckthorn (Rhamnus cathartica) .................................................................... 24
Garlic mustard (Alliaria petiolata)................................................................................... 24
Additional Resources ............................................................................................................ 25
Pesticide Laws .................................................................................................................... 25
Pesticide Labels ...................................................................Error! Bookmark not defined.
Plant Facts/Identification .................................................................................................... 25
Tools ....................................................................................Error! Bookmark not defined.
1
Project Overview
Non-native, invasive plant species have become common in many of New England’s forests.
Invasive species can out-compete native plants for nutrients, water, light, and germination
sites and often become the dominant vegetation type, threatening the regeneration of native
species important for wildlife habitat, biodiversity, and timber production. As a result, the
successful, long-term management of New England’s forests will increasingly depend on the
ability of land managers to develop and implement techniques and strategies to control
invasive species populations and restore native plant communities. The Northeastern Area
Invasive Forest Plant Species Project (NEA Invasive Project) was developed with funding
from the USDA Forest Service, State and Private Forestry to provide land managers with a
working knowledge of invasive plant ecology and strategies for control.
This booklet provides an overview of invasive plant ecology, traits, and general control
strategies, and serves as a guide to the NEA Invasive Project’s demonstration control plots.
The plots were designed to incorporate several invasive plant species often found in New
England’s forests and to showcase some commonly used control methods. Photographs and
written documentation of methods, labor, and materials are provided to help attendees
understand the scope and costs of the work involved. Demonstration plots were also mapped
and photographed at permanent photo plots to help evaluate the long-term response to
treatment, and to facilitate the use of the demonstration plots for future workshops. The plots
were designed in the spring of 2005 and control was implemented during the summer of
2005. The project was planned and managed through collaboration between the USDA
Forest Service, State and Private Forestry, the Vermont Department of Forests, Parks and
Recreation, including the Office of the Windham County Forester, the Windham County
Natural Resources Conservation District, and Ellsworth Land Management, LLC of
Somerville, Massachusetts. The project managers wish to acknowledge the landowners who
have kindly allowed access to their land.
Invasive Plant Ecology
When planning the prevention and control of plant invasions it is important to consider that
the success of invasive plants is often the result of multiple, interacting factors, most
important, the invasive plants’ traits and a site’s history of ecological disturbance. This is
analogous to how foresters consider the growth traits and ecological requirements, or silvics,
of timber species when planning regeneration cuts. However, the study of invasive plant
ecology is a relatively new and rapidly evolving field, and knowledge of the plants’ traits are
incomplete. Therefore, land managers should expect that new information on traits and
control strategies may be emerging in the coming years.
Plant traits
The reasons behind the relative success of invasive plants over native species are not well
understood. Environmental cues may differ between a plant’s native and adopted range. It is
also possible that predators and diseases that affect the species’ in its native range are not
present here, and as a result the invasive plants are able to devote energy to growth and fruit
production instead of chemical compounds to combat their natural enemies. In general,
invasive plants tend to grow vigorously in a range of conditions and produce a high number
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of viable seeds and/or reproduce rapidly through root cloning. The seeds of fruit producing
species are often dispersed long distances by wind, birds, other animals or water. Some
species have thorns, spines or chemical compounds that deter herbivores such as deer or
insects. In addition, several species of invasive plants, such as shrub honeysuckle (Lonicera
spp.) and Japanese barberry (Berberis thunbergii), leaf out earlier in the spring and/or hold
their leaves longer in the autumn compared with the native, deciduous trees in the overstory.
This trait gives the invasive plants a longer growing season and enables them to capture light,
water, and nutrients when the overstory is dormant.
Understanding the specific ecological traits of an invasive species helps land managers to
plan more effective monitoring and control. For example, the seeds of garlic mustard
(Alliaria petiolata) can persist in the soil seed bank; even after mature plants are removed,
seeds will continue to germinate for many years. By contrast, the seeds of Asiatic bittersweet
(Celastrus orbiculatus) do not remain viable in the seed bank for more than one year. If
control can effectively stop seed production by killing vines before the fruits mature in late
summer, few bittersweet seeds will germinate the next spring. Thus, a species’ seed bank
longevity will determine monitoring schedules and the time it takes to achieve effective
control. Other traits that are important to understand are: age of sexual maturity, season of
fruit maturation, seed dispersal method, and tolerance of shade.
Disturbance history
Ecological disturbances that kill existing vegetation or disturb the soil can result from natural
occurrences such as fire, windstorms, and heavy browsing by deer. Human activities such as
logging, road building, and cultivation are also causes of ecological disturbance. Since
disturbances free up growing space for new plants, they are necessary for native plant
community succession and biodiversity. However, because invasive plants grow rapidly,
produce large numbers of viable seeds, and may not be subject to herbivore damage, they
often are able to exploit disturbances more readily than many native species.
Due to the interaction between disturbances and invasive plant success, it is important to
consider the effects of future disturbances. For example, shade tolerant invasive plant species
such as Asiatic bittersweet (Celastrus orbiculatus), glossy buckthorn (Frangula alnus) and
Japanese barberry (Berberis thunbergii) become established in the forest understory and can
survive for years. An increase in light following the loss of established, dominant vegetation
can release these plants and cause a small invasive plant population to explode. Less shade
tolerant invasive plants, such as multiflora rose (Rosa multiflora) and autumn olive
(Eleaganus umbellata) need more light and are more likely to become established in areas
that have already been disturbed, such as old fields, large gaps, and forest edges.
Disturbance to the forest litter layer is also an important factor in the establishment of
invasive plants. Intact leaf litter can be a physical barrier to germinating seeds, especially in
the case of small seeds that have limited starch reserves to support cotyledon and radicle
growth. The surface of leaf litter can also be an extremely hot and dry micro-environment,
creating harsh conditions for seedlings. When leaf litter is removed or disturbed it increases
the amount of exposed soil and the chance that seeds will successfully germinate and become
established. When there are a high number of viable invasive species seeds present, leaf litter
disturbance often leads to invasive plant establishment.
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Deer browsing is suspected of being an ongoing form of disturbance that affects significant
areas of New England’s forests. The dominance of invasive plants and lack of native tree and
shrub regeneration in many New England forests may be due in large part to browsing deer
that prefer to eat native vegetation instead of the invasive species. The selective pressure of
deer browsing is thought to be especially important in the success of Japanese barberry,
which deer avoid because of its sharp thorns. Even after barberry and other species are
controlled, continued deer browsing should be expected to negatively impact native plant
regeneration. Successful restoration of treated sites may require deer exclusion methods.
Monitoring and Prevention
Early detection and control of invasive plant populations avoids costly large scale removal
projects and the accumulation of a soil seed bank. Monitoring should be a routine land
management practice—land owners should be vigilant while taking walks, foresters should
include invasive plant surveys in their management plan updates, and land trusts should
encourage committed and informed members to map populations. It is also important to take
note of neighboring properties, as they can be a source of seed and neighbors may be willing
to collaborate on plant control projects. When monitoring for invasive species, it helps to
anticipate likely sites of invasion, such as roadsides, trailheads, logging sites, forest and
water edges, sites in close proximity to invasive plant populations, and areas under fruitproducing plants that attract birds.
Successful prevention depends on early detection and control combined with limiting
disturbance so as not to create the light and leaf litter conditions that allow invasive plants to
become established and grow rapidly. If seed rain from invasive plants is a threat, foresters
should reduce leaf litter disturbance by limiting logging to the winter when the snow pack
protects the forest floor. If a forest stand is scheduled for logging or thinning, it should be
surveyed for the presence of invasive plants that could be released by the increase in light.
The plants should be controlled before logging because control can be hindered by logging
slash.
Planning Control and Restoration
Define objectives and assess resources
Invasive plant control is an ongoing, multiyear effort that requires careful planning for the
initial control work, follow-up, and restoration of native species. Sites will require different
levels of treatment ranging from minor hand-pulling of invasive plants to complete
ecosystem restoration. It is important to determine what the goal of a project is: Is it to
protect established, native plants? Remove invasive plants? Stop an invasive population from
spreading or fruiting? Restore a functioning native plant community? Is the goal realistic
given the ecological characteristics of the site and the resources available for control?
The feasibility of a project will be determined by ecological factors, such as the difficulty of
controlling a particular species and the availability of funding and labor. It is important to
predict the economic and/or volunteer resources that will be available for the initial control
project, for planting native species, and for ongoing maintenance. Also, some sites, such as
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wetlands, may have restrictions on the type of work that can be performed or require permits.
All of these factors should be assessed before a project is undertaken. When managing
property, there is always more work than there are hours in the day; pick battles carefully!
One important consideration when planning control is to ask whether the goal is to remove
invasive plants or to manage for native plants in spite of invasive plants. For example, should
all the honeysuckle be removed from a site, or only those that are in direct competition for
established white pine or native shrubs, such as Viburnum and spicebush? Both may be valid
strategies, but each has very different ecological and economic consequences.
Prioritizing sites
Due to the ecological and economic limitations on certain projects, prioritizing sites is very
important. In general, it is best to start control in intact native plant communities in which
invasive species are just becoming established. These native plant communities with
“satellite” invasive plant populations can be protected with a low investment in labor and
materials. Other high priority sites are forest stands that are scheduled for logging or
thinning. The sudden increase in light can release established invasive plants. It is preferable
to conduct control before logging, as the resulting slash can make access difficult and cover
target plants.
After the satellite populations are controlled, areas with higher numbers of invasive species
should be targeted, especially sites with seed producing, invasive plants. Large sites totally
dominated by invasive plants are often the last to be controlled. These sites should be
expected to require higher investments in control and replanting of native species.
Who will do the work: volunteers, landowners or professionals?
Depending on the property, invasive plant control may be conducted by landowners,
volunteers, or by professional, licensed vegetation control specialists. Professional crews
must be licensed and insured in your state and should be knowledgeable about common
invasive plants and the native plants that should be protected.
While landowners can apply unrestricted herbicides on their own property, a pesticide
applicator’s license is required to apply herbicides on another’s land. Consulting foresters
must have a valid commercial license to apply pesticides on their client’s land. Under
Vermont law, land trust members and employees require a non-commercial pesticide license
to apply herbicides on land held by land trusts. Since use of herbicides is an important tool in
combating invasive species, it is recommended that land trusts encourage several committed
volunteers or local landscape contractors to obtain the proper license so that herbicides are an
option on small control projects. Non-licensed workers can work under a license holder as
long as the license holder is on the job site. For information on the different pesticide
categories and for specific information on the laws governing the use of pesticides in
Vermont, visit http://www.vermontagriculture.com.
In the case of land trusts or public lands, volunteers can be an integral component in invasive
plant control efforts. Surveying and monitoring invasive species populations are excellent
activities for volunteers. Maps and photos of common invasive plants should be provided.
Volunteers can perform useful invasive species control work in appropriate sites: those with
species that can be effectively controlled through mechanical methods; those that are easily
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accessed for repeat treatments; and those where follow-up control is required. Replanting
native species following control is also an excellent task for volunteers. When organizing
volunteers for control or restoration efforts it is important to clearly define the goals for the
day, delineate project boundaries, and flag invasive plants that are to be removed or native
plants that are to remain. When working with larger groups of volunteers, it is often helpful
to divide the group into pairs and the project area into several work zones. Each pair can
proceed from zone to zone at its own pace.
Control Methods
Mechanical
Cutting and pulling invasive species are the most common methods of mechanical control.
While they can be effective for certain invasive species, others respond by putting out more
sprouts, which makes the problem worse.
Cutting/Mowing: The time of year is an important factor when using cutting to control
woody plants. Cutting plants in the spring just as the plant leafs out is the most effective. At
leaf out, the plant’s roots are depleted of stored carbohydrates as they move from the roots to
the branches in order to feed new growth. Removing the above-ground biomass at this time
maximizes the removal of carbohydrates. Subsequent cutting of resprouting stems throughout
the summer will further deplete the roots. By contrast, cutting during the winter does not
remove as many stored carbohydrates, and the plant will resprout vigorously in the spring.
Cutting or mowing a plant before its fruits mature can reduce its seed production. For
example, cutting in mid-summer can be used to stop seed production in Asiatic bittersweet
(Celastrus orbiculatus) vines. However, for cutting or mowing to effectively control the
overall vigor and spread of an invasive plant population, it must be done several times during
the growing season (June through September) and repeated for many years. Often, cutting is
practical only when it can be integrated into an existing field mowing plan.
Pulling: Pulling plants out of the ground can be effective on species that have shallow roots
and that do not reproduce through root suckering. For example, it is often possible to pull out
most of the root system of glossy buckthorn (Frangula alnus) and garlic mustard (Alliaria
petiolata). Some sprouting might occur, but reasonable control may be achieved. By contrast,
species such as Asiatic bittersweet and Japanese knotweed (Polygonum cuspidatum) have
extensive root systems that are hard to remove and that resprout vigorously from small
sections of root left in the ground. While it is hard to control these species through pulling, if
one comes across small, satellite populations of Asiatic bittersweet or other species, it may be
worth the time to pull them out to reduce the plant’s vigor. One downside of pulling is that is
disturbs the soil, which may provide a seed bed for other invasive plants to become
established. Pulling of plants can be aided by the Weed Wrench, a metal lever that grabs the
base of small trees and shrubs.
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Herbicides
Note on herbicides
This booklet provides an overview of the techniques that are commonly used to control
invasive plants with herbicides. The use and handling of herbicides and other pesticides are
regulated by state and federal laws. It is the responsibility of the landowner and any
employees or contractors to adhere to state and federal pesticide laws at all times. The
organizers and contractors working on The Northeastern Area Invasive Forest Plant Species
Project assume no liability for the improper or illegal use of pesticides by workshop
attendees or any of their employees or contractors. The Northeastern Area Invasive Forest
Plant Species Project does not endorse the use of any particular herbicide, nor does it
guarantee that the invasive plant control methods outlined in this plan will be effective. For
more information on the laws governing the use of pesticides in Vermont please contact:
Vermont Agency of Agriculture, Food & Markets
116 State Street, Drawer 20
Montpelier, VT 05620-2901
Phone: (802) 828-2416
Fax: (802) 828-3831
[email protected]
http://www.vermontagriculture.com
Common herbicide application methods
The method one uses to apply herbicide depends on such factors as target species, site
characteristics, herbicide type, and time of year. The most common herbicides used for
invasive plant control are systemic herbicides such as glyphosate (e.g., Roundup) and
trichlopyr (e.g., Garlon), although other herbicides are available and are preferred in some
cases. Wetland approved herbicides may be required near waterways in accordance with
Vermont regulations.
Systemic herbicides kill the plant by being absorbed into, and translocated throughout, the
plant tissue. It is important to apply herbicides when the plant is translocating carbohydrates
down to the roots (from early summer to early winter). It is also important to apply enough
herbicide to the aboveground parts of the plant to kill all the roots. With the cut-stump
method, concentrated herbicide is applied to a small surface area (the stump). Conversely,
with foliar spray, a low concentration of herbicide is applied to a large surface area (all the
leaves). Foliar spray will not kill the plant if it is applied only to a small percentage of leaves.
Regardless of method, it is important not to cut stems or roots of target plants for at
least 6 months to a year after the herbicide is applied. Herbicide takes months to work
its way through the plant’s vascular system, and cutting may disrupt its flow to living
tissue.
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Foliar spray
Foliar application of herbicides entails spraying the leaves of target plants during the growing
season with a low concentration of herbicide (0.75–3%) in water. Marking dyes, anti-drift
formulations, and surfactants should be added in accordance with the pesticide label. The
spray can be applied with a hand-powered, backpack sprayer or larger, motorized sprayers.
When applying foliar spray, cover all the foliage with the solution. Foliar spray treatments
should be conducted between early July and mid-September. At all times, applicators should
be aware of herbicide drift. Applicators should
spray with their back to desirable vegetation,
sensitive areas, and waterways, and avoid
spraying during windy days. Lowering tank
pressure and setting the nozzle opening wider
(more stream than spray) will lessen the potential
for drift. If spray contacts the foliage of desirable
vegetation, immediately cut off the affected
leaves or branches to minimize the absorption of
herbicide. One should avoid spraying tall
vegetation. In addition, the herbicide can take
many months to travel from the leaves to the
roots; therefore, it is important to wait at least a
Foliar spray
year before cutting the stems of woody vegetation
treated with foliar spray.
Cut-stump
The cut-stump method entails cutting vegetation near the ground and applying 50–100%
concentrate herbicide to the stump or stumps (in the case of multiple stemmed plants).
Herbicides should be applied immediately after the cut is made and should cover the plant’s
cambial tissue around the rim of the stem. Marking dye should be added to the herbicide to
indicate which stems have been treated. Cuts often are made with hand saws or pruners, but
chainsaws or gas-powered brush saws may be used on larger stems. Herbicide may be
applied with paint brushes, squirt bottles, foam applicators (e.g., bingo markers), and the
Sprout-Less system, which mounts on a brush saw and applies while it cuts. In addition to
protective equipment specified on the pesticide
label, eye protection and chemical resistant
gloves should be worn at all times. The cutstump method is time consuming, but it is very
selective. It should be used near sensitive,
desirable vegetation and on target plants that
cannot be foliar sprayed without a high risk of
drift (e.g., tall shrubs, trees, or vines). The cutstump method can be used any time the plant is
translocating sugars through the cambium down
to the roots. The general period for this activity
is from early July through November, although
Cut-stump
there is some evidence that fall application is
more effective.
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Basal spray
The basal-spray method involves the application of an oil-based herbicide and oil dilutant to
the bottom portion of a plant’s stem. The oil penetrates the plant’s bark and carries the
herbicide into the cambium for translocation to
the roots. Basal treatments generally are applied
using a sprayer at low pressure with a marking
dye. The concentration of herbicide in oil is
dependent on the product being used and the
application type. Consult pesticide labels for
treatment methods and mixture instructions.
The basal-spray method is similar to cut-stump
application in that it is highly selective and may
be used from early July through December. It
tends to be faster than cut-stump because
cutting is not required, but may require the
Basal spray
application of more active ingredient. Basal
spray formulations can also be applied to cutstumps that have begun to re-sprout.
Reducing non-target kill
It is important to avoid the unintentional killing of non-target species. Follow the application
guidelines outlined on the product label to reduce herbicide drift. Use common sense and
caution at all times. In some cases some non-target kill will occur. If spray contacts the
foliage of desirable vegetation, immediately cut off the affected leaves or branches to
minimize the absorption of herbicide. One way to reduce non-target kill is to protect a
significant portion of the desirable species before treatment begins. For example, in the week
before a scheduled foliar spray application, desirable plants close to or overgrown by
invasive plants should be cut cleanly at the stump. Many species will resprout the following
year. Another tactic is to limb the lower branches of small trees so that low-lying leaves will
not be hit by herbicide. The evening before spraying, especially desirable plants can be
covered with plastic sheeting, garbage barrels, traffic cones, etc. It is important not to leave
the plastic on for more than a few hours during the day, however, because heat stress will kill
the plants. Often, there are so many desirable plants that it is unrealistic to protect them all.
Limit pre-spray protection to rare species, those that are important to wildlife or timber
production, or to species that will quickly occupy growing space after control. Be careful not
to cut target, invasive plants before spraying because the translocation of herbicide to the
roots will not occur and control will be reduced. Please note that invasive species may
form root grafts with desirable native plants. While not common, herbicide applied to
an invasive plant might be translocated through the roots and damage non-target
vegetation.
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Restoration/Replanting
Following the removal of invasive plants, the site should be evaluated for the vigor, density,
and diversity of established native plants. Many native plants might survive the initial
control, new ones may seed in, or seeds may germinate from the seed bank. In many cases,
however, it is often necessary to replant native species to ensure that the site’s growing space
is occupied; otherwise invasive species will recolonize the site.
Restoring a site with the original array of native species can be quite expensive and time
consuming. In very sensitive sites with rare plant or wildlife species such an expense may be
warranted. Often, though, the main goal of replanting is to quickly occupy growing space
after control with fast-growing or easy-to-establish native species that grow in a range of
conditions. Select native species that are appropriate for the site. For example, if the site is in
the understory, plant shade tolerant species; if the site’s soil is wet or compacted by vehicles,
plant trees such as red maple (Acer rubrum), which tolerate poor soils; if heavy deer
browsing is a problem, plan on installing adequate fencing, plastic tree tubes or choose
unpalatable native species, such as eastern white pine (Pinus strobus) or black birch (Betula
lenta).
Before planting, evaluate whether invasive plant control was thorough. Delay planting or use
plastic tree tubes to protect planted stock if yearly foliar spraying of herbicides is required to
control resprouting plants or seed bank emergents. While they are often hard to find, try to
buy plants that come from local genotypes. Also be aware that many nursery-grown shade
tolerant species have spent their lives in full sun and they might experience shock if planted
in dense shade without acclimating. Nursery stock can be a vector for disease or have weed
seeds in their potting soil—check plants carefully. One option to reduce the threat from weed
seeds is to plant bare root stock, which tends to be less expensive and in some cases has
higher transplant success. One of the most common reasons for transplant failure is that stock
is planted too deep and the roots are smothered. It is important to learn to locate the root flare
at the base of the stem and install the plant so that the flare is slightly above ground level.
Also, it is important to schedule planting in the spring or fall to reduce watering needs.
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Guide to Demonstration Plots
Note: Due to the time limitations on this project, all control work was conducted during July
and August of 2005. Methods such as cut-stump and basal spray tend to be more effective in
the fall when the plant is more actively translocating carbohydrates down to the roots. As a
result, a reduced efficacy in those plots should be expected.
Site #1: Asiatic bittersweet control site (Scott Farm, Inc., Dummerston, VT)
Description
Site #1 is located in a white pine stand along a
field edge. Asiatic bittersweet had become
established in the understory and was
climbing up the low hanging branches and
trunks of the canopy trees. The age of the
invasion is not known. Few native plants were
present in the understory, primarily black
cherry (Prunus serotina) and raspberry (Rubus
spp.). The invasive shrub, common buckthorn
(Rhamnus cathartica), was also present. The
site was divided into treatment and control
plots in order to demonstrate the scope of the
work performed. The control plot had less
bittersweet than the treated plot, but it had a
similar structure (understory and climbing
plants). In addition, a small subplot was
delineated within the control plot in which all
native plants were cut the day before foliar
spraying so as to protect them from the effects
of the herbicide.
Because of the presence of both low lying and
climbing vines, the control work was
scheduled for two separate days. The larger
vines climbing into the trees were cut at about 5 feet high and at ground level with bypass
loppers or hand pruners. The cut surfaces of the stumps were painted with 100% Garlon 4
herbicide and Bas-Oil Red dye in a heavy-duty bingo marker (similar to a postage stamp
applicator). Vines that ran along the ground were carefully traced to each descending root
and cut for additional application. The following day, the low-lying vines were sprayed with
Garlon 4 at a 2.5% solution in water. Blue marking dye and 41-A anti-drift additive were
added at label rates. On very hot days Garlon 4 can volatize and drift into the forest canopy–
check manufacturer specifications before applying.
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Work summary (Asiatic bittersweet)
Location: Treatment plot.
Description: Cut-stump application to
climbing bittersweet.
Date: July 6th, 2005.
Weather: High 70’s and muggy.
Tools used: Bypass loppers, bypass pruners,
“bingo marker” applicator.
Chemical used: 100% Garlon 4 (EPA Reg. #
62719-40) with Bas-Oil Red marking dye.
Amount used: 2 oz.
Time: 1 hour, 35 minutes.
Notes: On vines running along the ground,
care was taken to trace them back to the roots.
Bittersweet site before control
Location: Native plant cut plot (within
control plot).
Description: Cutting of native plants in
preparation of foliar spray.
Date: July 6th, 2005.
Weather: n/a
Tools used: Bypass pruners and loppers.
Chemical used: n/a
Amount used: n/a
Time: 10 minutes.
Cut-stump technique
Location: Treatment plot.
Description: Foliar spray of low-lying bittersweet and
occasional common buckthorn.
Date: July 7th, 2005.
Weather: 70’s, calm with occasional breeze. Foliage wet from
heavy rain the night before.
Tools used: Solo 4 gal. backpack sprayer w/ brass cone
nozzle. Chainsaw to trim large pine boughs hit by spray.
Chemical used: 2.5% Garlon 4 (EPA Reg. # 62719-40), with blue
marking dye and 41-A anti-drift additive at label rates.
Amount used: 19.2 oz. concentrate to 6 gallons of water.
Time: 45 minutes of spraying, 30 minutes preparation and tank
mixing.
Notes: Goal was full coverage of leaves with spray solution. Effort
was made to avoid spraying the leaves of non-target natives. Leaves
of bittersweet vines that had been cut the day before were already
wilting.
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Cut-stump technique
Site #2: Honeysuckle control site (Elysian Hills Tree Farm, Dummerston, VT)
This site was clear-cut in 1995 to promote bigtooth aspen (Populus grandidentata)
regeneration for wildlife habitat. Instead, exotic shrub honeysuckle became established and
began to dominate the site. Scattered glossy buckthorn, common buckthorn and Japanese
barberry were also present. There was evidence of heavy deer browsing on native plants
besides the relatively unpalatable black birch (Betula lenta) and eastern white pine (Pinus
strobus) and it is possible that selective browsing may have been a factor favoring
honeysuckle and other invasive species.
The site was divided into 4 plots in order to demonstrate the following techniques: cut-stump
application of glyphosate by a two-person team, cut-stump application of glyphosate using
the Sprout-Less Brush Saw applicator, foliar spray of glyphosate, and basal spray application
of trichlopyr. Cut-stump and basal spray
application are known to be effective on
controlling shrub honeysuckle, while the
foliar spray has been reported to have
mixed results. When comparing the longterm efficacy of the cut-stump hand
treatment (Plot 1) and the Sprout-Less
Plot 4
Plot 3
treatment (Plot 2), attendees should
consider that Plot 2 was treated 3 weeks
later, at a time when downward
translocation of sugars was more likely.
Honeysuckle site before control
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Work summary (Honeysuckle)
Location: Plot 1
Description: Cut-stump herbicide application.
Date: July 18th, 2005.
Weather: Hot, humid, overcast.
Tools used: One person running a chainsaw or
loppers, one person with “bingo marker” style
applicator.
Chemical used: 100% Glypro (EPA Reg. #
62719-324) and blue dye.
Amount used: 5.5 oz.
Time: 2 hours (4 hour labor cost due to two
person crew).
Notes: Heavy rain soon after application. Early in
season for cut-stump– reduced efficacy?
Cut-stump technique: Plot 1
Location: Plot 2
Description: Sprout-Less brush saw application.
Date: August 11th, 2005.
Weather: Hot and humid.
Tools used: Sprout-Less brush saw applicator and
Husqvarna 250 brush saw.
Chemical used: 100% Glypro (EPA Reg. # 62719-324)
and blue dye.
Amount used: 4 oz.
Time: 1.5 hours.
Notes:
The Sprout-Less System
Location: Plot 3
Description: Foliar spray.
Date: July 25th, 2005.
Weather: Hot, humid, overcast, calm.
Tools used: 4 gallon Solo backpack sprayer,
adjustable brass cone nozzle.
Chemical used: 2% Glypro (EPA Reg. # 62719324), with marking dye and 41-A anti-drift additive
at label rates.
Amount used: 5 oz. concentrate in 2 gallons of
water.
Time: 20 minutes.
Notes: Since vegetation was high, effort was made to
fully cover lower and mid-level foliage. Upper
Plot 1 after cut-stump treatment
foliage was sprayed when it was possible not to cause
drift on to non-target plants. Spray was directed away
from desirable white pines and black birch when
possible and leaves were removed when they were hit by spray. Some non-target application
occurred.
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Location: Plot 4
Description: Basal spray.
Date: July 25th, 2005.
Weather: Hot, humid, overcast.
Tools used: 4 gallon Solo backpack sprayer,
adjustable brass cone nozzle.
Chemical used: Pathfinder II (EPA Reg. # 62719176) and Bas-oil red marking dye.
Amount used: 103 oz.
Time: 45 minutes.
Notes: Applied to bottom 10-18 inches on all stems.
Basal spray technique: Plot 4
Site #3: Glossy buckthorn control site (Aquadro property, Dummerston, VT)
The glossy buckthorn control site is located within a white pine stand. Glossy buckthorn
dominated the forest understory and midstory. A significant number of sugar maple (Acer
saccharum) was
also present in the
midstory. The site
was divided into 4
plots: cut-stump
application of
glyphosate by a
two-person team,
cut-stump
application of
glyphosate using the
Sprout-Less Brush
Saw applicator,
basal spray
application of
trichlopyr, and a no
treatment control. A buffer of untreated vegetation was also left along the edge of the lawn to
provide a screen for the property owner.
15
Work Summary
Location: Plot 1
Description: Sprout-Less brush saw application.
Date: August 11th, 2005.
Weather: Hot and humid.
Tools used: Sprout-Less brush saw applicator and
Husqvarna 250 brush saw.
Chemical used: 100% Glypro (EPA Reg. # 62719324) and blue dye.
Amount used: 3.5 oz.
Time: 60 minutes.
Notes:
Location: Plot 2
Description: Basal spray.
Date: July 25th, 2005.
Weather: Hot, humid, overcast.
Tools used: 4 gallon Solo backpack sprayer, adjustable
brass cone nozzle.
Chemical used: Pathfinder II (EPA Reg. # 62719-176)
and Bas-oil red marking dye.
Amount used: 110 oz.
Time: 1 hour, 10 minutes.
Notes: Applied to bottom 10 inches on all stems.
Careful not to have runoff from buckthorn stems
around the base of canopy pines.
Buckthorn site before control: Plot 2
Plot 3 after cut-stump treatment
Location: Plot 3
Description: Cut-stump herbicide application.
Date: July 18th, 2005.
Weather: Hot, humid, overcast.
Tools used: One person using loppers, one person with “bingo marker” style applicator.
Chemical used: 100% Glypro (EPA Reg. # 62719-324) and blue marking dye.
Amount used: 1 oz.
Time: 40 minutes (1 hour, 20 minutes labor cost due to two person crew).
Notes: Heavy rain before application. Early in season for cut-stump– reduced efficacy?
Site #4: Japanese barberry control site (Evans property, Dummerston, VT)
The control work on Site #4 was conducted on the Evans property during the summer of
2004 with funding from the USDA Wildlife Habitat Incentives Program (WHIP). Ellsworth
Land Management, LLC was hired under a private contract to perform the work. The primary
target of the control work was Japanese barberry (Berberis thunbergii) which dominated the
site. Common barberry (Berberis vulgaris), common buckthorn (Rhamnus cathartica),
Asiatic bittersweet (Celastrus orbiculatus), and winged euonymus (Euonymus alata) were
present and were also targeted. The majority of the Japanese and common barberry was
controlled using a glyphosate (Glypro or Accord) foliar spray at 2.5% applied with backpack
16
sprayers. Large shrubs in gaps and along the field edge were treated with 100% glyphosate
using the cut-stump method. The Sprout-Less system was used in limited areas. Large
Asiatic bittersweet vines were treated with Garlon 4 applied using the cut-stump method.
A visit to the Evans property has been included in the NEA Invasive Project workshop
because it allows attendees to view several things: an example of Japanese barberry control
work, how a site looks a full year after control was completed, and the labor and material
costs involved in a large sized control project.
Work summary
Location: Evans Property
Area treated: 8.4 acres.
Description: Foliar spray of Japanese barberry and other
invasive plants. Cut-stump method used on tall shrubs and
vines.
Date: August 3rd through September 14th, 2004.
Weather: Warm, calm.
Tools used:
• 4 gallon Solo backpack sprayer, adjustable brass
cone nozzle.
Barberry 1-year after foliar spray
• Sprout-Less brush saw applicator.
• “Bingo marker” herbicide applicator.
Chemicals used:
• Foliar spray: 2.5% concentration of Glypro (EPA
Reg. # 62719-324) or Accord (EPA Reg. # 62719322) with marking dye, surfactant, and 41-A antidrift additive at label rates.
• Cut-stump: 100% Glypro (EPA Reg. # 62719-324)
or Accord (EPA Reg. # 62719-322) and blue
marking dye. 100% Garlon 4 (EPA Reg. # 6271940) with Bas-Oil Red marking dye used on
bittersweet.
Amount of concentrate used:
• Glypro– 2.2 gallons
Barberry 1-year after foliar spray
• Accord– 0.4 gallons
• Garlon 4– 1.7 oz.
Time: 55 labor hours (including preparation, clean-up, and tank mixing). Approximately 110
gallons of 2.5% spray mixture were applied.
Notes: Spray was directed away from desirable plants when possible and leaves were
removed when they were hit by spray. Some non-target application occurred.
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Common Invasive Species Found in New England Forests
Shrubs/trees
Japanese barberry (Berberis thunbergii)
Common barberry (Berberis vulgaris)
Shrub honeysuckle (Lonicera spp.)
Winged euonymus (Euonymus alata)
Norway maple (Acer platanoides)
Multiflora rose (Rosa multiflora)
Autumn olive (Eleaganus umbellata)
Common buckthorn (Rhamnus cathartica)
Glossy buckthorn (Frangula alnus)
Vines
Asiatic bittersweet (Celastrus orbiculatus)
Herbaceous
Japanese knotweed (Polygonum cuspidatum)
Garlic mustard (Alliaria petiolata)
Goutweed (Aegopodium podagraria)
Invasive species that could become a serious threats in Vermont
Japanese stilt grass (Microstegium vimineum)
Mile-Minute-Vine (Polygonum perfoliatum)
Black swallow-wort (Cynanchum louiseae)
Pale swallow-wort (Cynanchum rossicum)
Porcelainberry (Ampelopsis brevipedunculata)
Invasive Species: Descriptions, Ecological Traits, and Control
Note: This section outlines general plant traits and control techniques. Further information
on plant identification and specific control methods are available in print and on numerous
websites– several of which are listed in the “Additional Resources” section of this booklet.
Asiatic bittersweet (Celastrus orbiculatus)
Description
Asiatic bittersweet is a woody, twining vine with
deciduous, alternately arranged leaves. It can
climb high into tree tops, or grow in a low shrub
like form in open areas. New stems are light
green and second-year (or older) stems are brown
to gray. Leaves are oval or circular in shape. The
flowers and fruits of Asiatic bittersweet are
located in groups at the base of leaves, along the
stem. The fruits mature by early fall and have a
yellow covering that recedes to expose fleshy red
or orange axils that contain the seeds. Asiatic
bittersweet spreads through seed dispersal by
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Asiatic bittersweet
Photo Courtesy of IPANE
birds and mammals and through root suckering. It can become established and survive in
dense shade (shade tolerant), but it grows rapidly when light levels increase. Evidence
suggests that the seeds of Asiatic bittersweet do not remain viable in the seed bank past one
year.
Control
Mechanical control of bittersweet is limited. Small- to medium-sized bittersweet plants that
are not growing in dense clumps can be hand pulled, but any roots left in the ground will
resprout. Large vines that are strangling trees or are producing fruit should be cut by midAugust, before the fruits mature. Cut the vines as high as possible and down at ground level.
Don’t try to pull vines out of the host tree--it will only damage the crown.
Asiatic bittersweet can be controlled with herbicides. Foliar spray low-lying vines (below
head height) during July through early-September. Cut-stump application should be used on
larger bittersweet vines when foliage has climbed above an acceptable spraying height. It is
important to note that herbicides containing the active ingredient trichlopyr are the most
effective on bittersweet. Large and small vines may be treated at different times. Cut-stump
application can be conducted on large, high climbing vines in the fall and then smaller,
surviving stems can be foliar sprayed the following summer. The reverse order may also be
used, with an initial foliar spray in the summer followed by cut-stump on large vines in the
fall. If possible, control fruiting vines before the fruits mature in September.
Japanese barberry (Berberis thunbergii)
Description
Japanese barberry is a spiny, deciduous shrub with arching branches. Plants commonly range
from 2 to 6 feet high. Japanese barberry flowers from mid-April to May in the Northeast and
the fruits mature from July to October. The branches are brown and covered with sharp
spines. The interior of the stems are bright yellow (apparent when the stems are cut or
broken). The leaves are teardrop to oval in shape, and are 0.5–1.5 inches long. Leaf color
ranges from bluish-green to green to dark red or purple, although its new leaf growth is light
green. Japanese barberry leafs out before many native
Japanese barberry
plants in the spring, at which point its light green
foliage becomes very noticeable. It has pale yellow
flowers and football-shaped, bright red berries (0.25–
0.35 inches long) that hang like pendulums along the
length of the stem. Japanese barberry reproduces by
seed and clonally when arching branches touch the
ground and form roots. It is can become established
and survive in dense shade (shade tolerant), but can
grow rapidly when light levels increase. The spines
Photo Courtesy of IPANE
deter deer.
Control
Hand-pulling of Japanese barberry in the spring may be effective at controlling seedlings and
small plants, although roots left in the ground will give rise to new shoots. Due to the sharp
spines, long sleeves and heavy-duty, leather gloves should be worn. Japanese barberry can be
controlled with foliar and cut-stump applications of herbicide. Foliar spray treatments should
be conducted between early July and mid-September. Cut-stump application should be used
19
in the fall. Follow-up treatment methods are the same as those used initially. May is a good
time for monitoring Japanese barberry because it leafs out earlier than many other plants and
is easy to locate. Do not spray before July, however, because during the spring plants are
translocating their sugars away from the roots.
Shrub honeysuckcle (Lonicera spp.)
Description
There are many species and ornamental crosses in
Shrub honeysuckle
the honeysuckle family, and telling them apart can
be quite difficult. Therefore, for the sake of
management, they are lumped together as shrub
honeysuckles (as opposed to vine honeysuckles).
Shrub honeysuckles have grayish to brown woody
bark and grow in an arching shape. The light green
leaves are oblong and oppositely arranged on the
stem. The stems of the exotic honeysuckles are
hollow. The flowers range from yellow to white to
red in color (depending on the species) and the
fruits are fleshy and bright red. The fruits of the different species mature from mid-summer
to mid-autumn. Shrub honeysuckles are shade tolerant and leaf out earlier in the spring than
many native plants. It has been reported that the seeds remain viable in the soil seed bank.
Control
Honeysuckle sprouts vigorously from the stump so cutting is ineffectual. Honeysuckle has a
relatively shallow root system; therefore, pulling has been reported to work in some
instances—care must be taken to remove as much root as possible. Foliar, cut-stump and
basal spray herbicide applications are reported to control shrub honeysuckles. If possible,
treat honeysuckle before the fruits mature. Honeysuckle seeds are reported to remain viable
in the seed bank for many years. Therefore, treated sites should be monitored yearly for new
seedlings and treated accordingly.
Winged euonymus/Burning bush (Euonymus alata)
Description
Euonymus alata is a woody, deciduous shrub with
oppositely arranged, dark green leaves that turn bright red
in autumn. It is named “winged euonymus” because most
cultivars have 2–4 corky flanges, or wings, that run along
the branches. Euonymus alata flowers from late April to
June and the reddish-purple fruits mature in September or
October. Each fruit contains 4 seeds, which are dispersed
by birds and gravity. Euonymus alata tolerates a range of
light levels and soil conditions and, therefore, is a threat in
both understory and open environments. The seed bank
longevity is not known, although anecdotal evidence
suggests that its seeds do remain viable in the seed bank.
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Winged euonymus
Photo Courtesy of IPANE
Control
Euonymus seedlings may be pulled out in the spring when the soil is moist. Try to control
larger plants before the fruits mature in September. Euonymus may also be treated with a
foliar herbicide application. Plants that are too tall for foliar spray can be controlled with cutstump or basal bark applications. Monitor treated sites for new seedlings, seed bank
emergents, and plants that were missed in the initial treatment.
Japanese knotweed (Polygonum cuspidatum)
Description
Japanese knotweed is an herbaceous perennial that grows
rapidly, reaching 3–10 feet in height, and forms dense
Japanese knotweed
monotypic stands. The stems are round and hollow and
Japanese knotweed
the leaves are oblong and large (3–6 inches across).
Japanese knotweed produces greenish-white flowers in
clusters from the top of the plant in August and
September. The fruits are winged and papery, each
containing 3 black achenes. Despite fruit production,
Japanese knotweed reproduces primarily through
rhizomes, which grow up to 65 feet in length and give
rise to new shoots. It dies back with the onset of frosts in
the fall, leaving dead, brown-to-purplish stalks
throughout the winter. Japanese knotweed grows well in
most soil conditions, but prefers wet soils and riparian
areas. It tolerates moderate shade, but is not often found in dense understories.
Control
Due to its capacity for rapid and prolific vegetative reproduction, Japanese knotweed is
particularly difficult to control. Pulling is ineffective and cutting will only work if it occurs
often, consistently, and over the long-term, as in a lawn setting. Herbicides can be
moderately to highly effective. One method is a cut-stump application. Another is to cut the
plant between leaf nodes and inject the hollow stem with 35% solution aquatic glyphosate
and water. Foliar spray in late August may also work on mature plants, or on plants that have
been cut down and allowed to resprout.
Multiflora rose (Rosa multiflora)
Description
Multiflora rose is a perennial shrub with arching
canes. It grows up to 15 feet tall, but it can grow
higher when it uses trees or other structure for
support. The canes are red to green in color and
have recurved thorns. Its leaves are alternately
arranged and are compound, having 5–11 toothed
leaflets. The leaflets are 1–1.5 inches long.
Multiflora rose has white to pink flowers that come
out during May and June. The fruits are red and
develop by mid- to late summer. Multiflora rose
reproduces via seeds that are dispersed by birds and
by layering (when canes send up new shoots after
21
Rosa multiflora
Photo Courtesy of IPANE
bending over and contacting the soil). The seeds remain viable for 10–20 years in the soil
seed bank. Multiflora rose grows in a range of soil conditions and habitats, but is intolerant of
dense shade.
Control
Multiflora rose sprouts vigorously from the stump, so cutting is ineffectual. Pulling may
control seedlings and young plants—care must be taken to remove as much root as possible.
Rose can be controlled with a foliar, cut-stump, and basal spray applications of herbicide. If
possible, treat rose before the fruits mature in late summer. Multiflora rose seeds are reported
to remain viable in the seed bank for many years, so treated sites should be monitored yearly
for new seedlings and treated accordingly.
Autumn olive (Eleaganus umbellata)
Description
Native to Asia, autumn olive has become common in much of New England. It is a large
shrub that has a noticeable silvery-gray sheen to its leaves. The leaves are lanceolate to
oblong-lanceolate in shape and are alternately arranged on the stem. One of the most
distinctive characteristics of autumn olive is that its leaves, twigs, branches, and yellow-tored fruits are covered with tiny silver scales, making them look as if they have been sprayed
with a fine mist of silver paint. Autumn olive most often is found in old fields and along
roadsides, and it is thought to be relatively intolerant of shade.
Autumn olive fruits
Autumn olive
Photo Courtesy of IPANE
Photo Courtesy of IPANE
Control
Autumn olive sprouts vigorously from the stump, so cutting is ineffectual. Pulling may
control seedlings and young plants—care must be taken to remove as much root as possible.
Foliar, cut-stump and basal spray herbicide applications are reported to control Autumn
olive. If possible, treat autumn olive before the fruits mature. Treated sites should be
monitored yearly for new seedlings and treated accordingly.
22
Common barberry (Berberis vulgaris)
Description
A native of continental Europe, common barberry was
Common barberry
at one time more prevalent in the U.S., but was the
target of a successful eradication effort because it is an
alternate host to a wheat rust. It is similar looking to
Japanese barberry, but it grows taller (10 feet) and has
a slightly more upright form (i.e., the branches are less
arched). The branches are gray and spiny. The leaves
are roughly the same shape as those of Japanese
barberry, but they are dull green in color, are slightly
larger (0.75–2 inches long), and have a finely toothed
Photo Courtesy of IPANE
edge. Common barberry has yellow flowers that appear
from late May and early June. The fruits are red,
football-shaped berries, like Japanese barberry, but instead of small groupings of berries that
hang directly from the stem, the fruits of common barberry hang in cascading bunches.
Common barberry reproduces the same way as Japanese barberry (seed dispersal and
vegetative reproduction) and also appears to be shade tolerant.
Control
Control common barberry with the same methods used on Japanese barberry.
Glossy buckthorn (Frangula alnus)
Description
Glossy buckthorn is a deciduous small tree or shrub (6–20 feet
tall). The leaves are alternately arranged on the stem and are
oval in shape. The leaves are a glossy, dark green color on top
and lighter underneath. It is often confused with black cherry
(Prunus serotina), but unlike black cherry, the edges of the
leaf do not have teeth. The roots are dark red. Glossy
buckthorn has fruits that change from red to black as they
mature. Fruit maturation occurs in July and continues through
the early fall. Seed dispersal is the main method of
reproduction. It is shade tolerant and holds its leaves late into
autumn after most native species have lost their leaves. It is
not known whether the seeds remain viable in the soil seed
bank.
Glossy buckthorn
Photo Courtesy of IPANE
Control
While cutting does little to control glossy buckthorn, pulling is an effective means of
controlling small and mid-size plants (up to an inch in diameter). The Weed-Wrench is an
effective aid for pulling buckthorn. Pulling will be less likely to work on large, multiplestemmed plants because of the extensive root system. Since pulling is time consuming and
causes soil disturbance, large infestations should be controlled with herbicide. Foliar, cutstump and basal spray herbicide applications can be used. One of the complicating factors in
controlling glossy buckthorn is that it fruits in early summer, but control is more effective
when performed in late summer, fall, or early winter. The benefits of controlling early to
23
avoid fruiting must be weighed against the reduced control. In either case, follow up will be
necessary to monitor for seedlings and resprouting.
Common buckthorn (Rhamnus cathartica)
Description
Common buckthorn is a deciduous small tree or shrub
(6–20 feet tall). The ends of the branches have thick
spines. The leaves often are oppositely arranged on the
stem and are roughly oval in shape. Unlike glossy
buckthorn (Frangula alnus), the leaves have small teeth
on the edges, and have veins on each side that are curved
along the leaf margin. Common buckthorn has black
fruits that mature in autumn; seed dispersal is the main
method of reproduction. It is shade tolerant and holds its
leaves late into autumn after most native species have
lost their leaves. It is not known whether the seeds
remain viable in the soil seed bank.
Common buckthorn
Photo Courtesy of IPANE
Control
Control common buckthorn with the same methods used on glossy buckthorn. However,
since the fruits of common buckthorn mature in the fall, there is more time for control before
fruiting occurs.
Garlic mustard (Alliaria petiolata)
Description
Garlic mustard is an herbaceous biennial that grows 1–3 feet high in its second year of
growth. During the first year the plant forms a basal rosette of leaves. The basal rosette
remains green throughout the winter and then begins growing vertically in its second year.
The leaves on the basal rosette are dark green and kidney shaped, while the leaves on secondyear, fruiting stalk are alternately arranged and triangular in shape. The leaves have toothed
margins and smell like garlic when crushed. Garlic mustard has white flowers in terminal
clusters that come out in April and May. The fruits develop in May and are thin, 1–2 inch
long pods that contain 10–20 seeds. It is thought that the seeds remain viable in the seed bank
for at least 5–7 years. It grows in a range of habitats and is a serious pest in the forest
understory.
Garlic mustard– 1st year rosette
Photo Courtesy of IPANE
Garlic mustard– 2nd year
Photo Courtesy of IPANE
24
Control
Due to its persistent seed bank and rapid spread, it is important to control garlic mustard
when the invasion is in its early stages. Small populations should be controlled by hand
pulling the second year plants before they set seed in May. The plants should be placed in
plastic bags and thrown out in the trash (not the compost). This is an excellent activity for
volunteers or school groups because the flowering plants are easily recognized and pulling is
not difficult. Very large populations can be controlled with a foliar application of herbicide.
Spraying should occur in early spring or late fall when other vegetation is leafless. Due to the
seed bank, however, pulling or spraying must occur annually for many years.
Additional Resources
Pesticide Laws
Vermont Agency of
Agriculture, Food & Markets
116 State Street, Drawer 20
Montpelier, VT 05620-2901
Phone: (802) 828-2416
Fax: (802) 828-3831
[email protected]
http://www.vermontagriculture.com
Plant Facts/Identification
Invasive Plant Atlas of New England
http://invasives.eeb.uconn.edu/ipane
TNC Wildland Weeds
http://tncweeds.ucdavis.edu/esadocs.html
Invasive and Exotic Species of North America
http://www.invasive.org
Invasive Plants Association of Wisconsin
http://www.ipaw.org
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