FINAL REPORT
“Semi-Aquatic Invasive Plant Best Management Practices”
LC-9991923-01 NEI Job Code 0980-001 Project Code L-2003-028
by the Boquet River
Association, Inc.
November 30, 2004
TABLE OF CONTENTS
page
Executive Summary 2
Specific Tasks & Outcomes 2
List of priority sites, square yard infestation,
management practices,
timing
& stem densities 7
Results 8
What are future options at the Willsboro and
Westport sites? 11
Attachment A – ACCESS database report on invasive
plant species found
along
road right-of-ways and on town properties in Willsboro and Westport;
and
altered database form to reflect control efforts
Attachment B – Workshop agenda and handouts
Attachment C – Workshop maps
Attachment D – Follow-up notes from workshop &
suggested best management
control
practices at priority sites
Attachment E – Photos of each site
FINAL REPORT
The
Boquet River Association (BRASS), in cooperation with town highway
departments, initiated best management control practices in 2004 on
terrestrial invasive plant species along right-of-ways (ROWs) and
town-owned properties in Willsboro and Westport, New York. Ten sites were prioritized for controls
due to: road safety when visual
ROWs and road signs were obscured; plant dispersal concerns at public
spaces and in a highway maintenance yard; image and education/outreach potential
at a town hall; sensitive environmental areas near water and in parks; and
future expansion potential of biological control agents. The ten target sites included stands of
Japanese knotweed (Polygonum cuspidatum), common reed (Phragmites
australis), purple loosestrife (Lythrum salicaria), and garlic
mustard (Alliaria petiolata). At a
specially convened May workshop for local, county and state highway
personnel, partners of the Adirondack Invasive Plant Program (the
Adirondack Park Agency, the NYSDOT, the Adirondack Nature Conservancy, Cornell
Cooperative Extension, and BRASS) provided training in identification,
assessment, and rapid response control methods for terrestrial invasive
plants. Appropriate best management
control practices were suggested for each of the ten sites, including preparatory
work, permits, timing, equipment/material/personnel needs, secure transport
and disposal of plants, and approximate costs. These
best management control practices were carried out from May through the
first week of October. Invasive
plant stands were pulled, cut, swabbed or foliar sprayed with herbicide, or
tarped according to the suggested controls at each site. Several herbicides (Garlonâ4, Garlonâ3A, Roundupâ, Rodeoâ, and Triamineâ) were applied at
varying concentrations. Results
from control practices varied by site and invasive plant species. Although judgment should be suspended at
least into the 2005 field season, it appears that pinning mats over cut
Japanese knotweed stems may prove the most cost-effective and
environmentally benign method of controlling knotweed.
Executive Summary
Specific Tasks and Outcomes
1 & 2- Inventory town
and county road ROWs and town-owned properties in the Lake Champlain watershed
areas of the towns of Willsboro and Westport for invasive plant species
occurrences, measurement of stands, and population densities. (Utilize the same procedures as used on the
previous LCBP-funded invasive plant inventory grant). Obtain landowner permission for inventories, when needed.
Unusual snow accumulations during December 2003 hampered inventories of invasive plants, however all inventories were completed by early spring 2004 except for garlic mustard (that cannot be detected until early spring growth). Every town and county road right-of-way in Willsboro and Westport was assessed, along with town-owned properties. A few garlic mustard stands were located and inventoried in May of 2004. All information was recorded on field sheets. Fourteen sites with invasive plant species in Willsboro were on town road right-of-ways or on town-owned property; 7 of these sites had more than one invasive plant species. (Nine sites were located on County road right-of-ways.) Fifteen sites in Westport were on town road right-of-ways or on town-owned property with 11 of these sites containing multiple invasive plant species. (Two sites along County roads were identified in Westport.)
3- Enter all data into a
database. Utilize an ACCESS database to
assure shared access by APIPP’s primary partners (NYSDOT, NYSDEC, the
Adirondack Park Agency, and the Adirondack Nature Conservancy).
Data from field sheets were
entered into an ACCESS database. (See
Attachment A, including a map of invasive species found in each town.) Later the database was refined to provide
information on control measures at priority sites. (See last page of Attachment A.)
4- Coordinate a training
program in identification of, and possible control measures for, invasive
plants. Please click here
to link to the minutes of the workshop on General Highway Practices.
An early May training program
date was selected so controls could begin early enough to gauge their
effectiveness during the grant period.
The Town of Westport agreed to host the workshop in their Town
Hall. This was a convenient location as
all four invasive plants could be found growing in the immediate vicinity for
positive identification purposes.
BRASS designed a tentative
training workshop agenda, with objectives, tasks, and potential speakers. This was shared with APIPP’s primary
partners for their review and comments.
The proposed workshop was reviewed so favorably that APIPP decided to
use it as a model for future training of NYS highway personnel at NYSDOT’s
County Residencies in the Adirondack Park.
(See Attachment B for a 2-page workshop planning document by BRASS sent
to all presenters, and a copy of the agenda and samples of workshop
handouts. Maps available at the
workshop are in Attachment C.)
Letters
and invitations to the BRASS workshop were sent to all town supervisors and
village mayors in Essex County, to all highway superintendents in all the towns
and villages, to the county Department of Public Works, and to the NYSDOT Essex
County Residency in Elizabethtown. The
training program was held on May 10th from 1-4:00 PM. Nineteen highway department personnel and
town officials attended.
Highway
department superintendents in Willsboro and Westport selected priority sites
for control efforts prior to the workshop (see task #5, below), which allowed
all workshop attendees to join a point-by-point discussion of what was required
to effectively control plants at each selected priority site. The discussion included preparatory work,
permits, timing, equipment and personnel needed, disposal of plants, and
approximate cost.
BRASS
developed a review of the workshop for highway department personnel. (See Attachment D.) This was first sent to the presenters for
comments and approval before being distributed. Two pages consist of general advice emanating from the workshop,
and two pages reflect the decisions made--and questions raised--about best
management controls practices for the priority sites in Willsboro and
Westport.
5- Work with town officials & road crews to
assess and rank targets for controls. At various meetings, and
with assistance from Steven Flint from the Adirondack Park Invasive Plant
Program, priority sites were chosen for specific types of control measures by
the Willsboro and Westport highway superintendents (Peter Jacques and Jerrold
Sherman, respectively). Each superintendent selected five sites.
Two
of the five sites in Willsboro were high priority due to significant
obstruction of the visual right-of-way and road signs by tall Japanese knotweed
(Fish & Game Road and Coonrod Road).
Japanese
knotweed at Memorial Park was the third selected
site.
The plants spread from the back of the park down to the edge of the Boquet River and had been mown repeatedly for years by the Willsboro highway department. No doubt, mown fragments had entered the river and were responsible for many of the downstream plant infestations. Noblewood Park on Lake Champlain, at the mouth of the Boquet River, was the fourth choice for implementation of controls. Great effort has been made to keep this lovely forested ~100 acre parcel in its natural condition while also permitting a town beach and summer day camp. Small, scattered Japanese knotweed plants were discovered near a tent site in the nature preserve area of the park. It is believed they were probably transported to the park in fill dirt when the primitive tent sites were being created. In addition, it is likely garlic mustard was imported in fill dirt or hay mulch when a camp road was constructed to the beach for handicapped individuals and emergency personnel.
A
fifth site was added because a private landowner desired biological control (Galerucella
beetles) for purple loosestrife on his property bordering both the river and
Lake Champlain. If the beetles
controlled loosestrife here, it was reasoned, they would soon migrate to
Noblewood Park and to other affected properties along the river and lake.
Two
target sites selected in Westport were for sensitive, ecological
reasons, and located along Merriam’s Forge Road where Japanese knotweed stands
grew in the ROW and continued to the banks of the Boquet River. (A private landowner was very concerned
about the knotweed and had attempted control efforts the previous year, with
advice from BRASS.)
The
third Westport site was for public image and education/outreach; an
impressively large and mature stand of knotweed grew immediately behind the
town hall.
The
Westport highway garage property was the fourth target site. Here, Phragmites and loosestrife grew in
numerous stands in and around machinery and piles of sand, gravel, and ditch
diggings. Seed and plant parts could
easily be distributed by equipment and road materials throughout Westport by
the highway department.
As
in Willsboro, a private landowner along the river (and also along a major
highway) wished to attempt biological control of purple loosestrife. This became the fifth Westport site.
Invasive plants do not limit themselves to just the historically maintained and disturbed ROWs, but spread onto adjacent properties. Therefore, BRASS contacted five private landowners for permission to control entire invasive plant stands in the selected priority sites of Willsboro and Westport. All landowners were cooperative with the project once they received information about the invasive plants and control options. Landowners on Coonrod Road in Willsboro, where knotweed plants obscured a “yield ahead” intersection sign, requested no herbicides use. Although complicating invasive plant control at this particular site, the sandy soils, nearby well, and children and pets, were decisive elements in selection of alternatives to herbicide treatment.
6- Stake out plots and measure stems for
post-control comparisons. Ten by ten foot plots were
not staked for a variety of reasons: by
the time priority sites were selected knotweed patches were either too tall and
dense to penetrate with measuring and staking devices; invasive plants were too
small and scattered, or in a long linear strip; some knotweed stands had been
repeatedly mown earlier so stems were very small and close together; some plant
stands had been subjected to prior herbicide treatment; and the protocols for Galerucella
beetle monitoring for loosestrife stands required 1-meter square plots. Therefore to compare pre- and post-controls
via 10’x 10’ plots was not a satisfactory device and became problematic. Because BRASS was advised to treat plants
when they were at their most susceptible stages, there would be no standard
timed intervals between applying controls. Also, weather conditions influenced
herbicide applications. Therefore,
average stem diameters and height could not be used to judge the efficacy of
post-control comparisons because of the erratic timing intervals. Instead, BRASS decided to utilize average
stem counts and anecdotes to describe the results of various control treatments.
7- Purchase/obtain appropriate materials for
controls. All materials were purchased, with the
exception of the herbicide. The
herbicides selected for use could only be purchased by licensed applicators. Therefore, the first herbicides applied by
NYSDOT were a match to the grant; a private licensed applicator, utilized for
follow-up control treatments, was reimbursed by BRASS for time plus herbicide
costs.
Heavy
black waterproof tarps (6 oz./yd2, 1000 denier, 14 x 14 weave count)
were purchased as an experimental attempt to smother (deny sunlight and water
to) Japanese knotweed on Coonrod Road where sandy soils and a nearby well
precluded the use of herbicides. The
plants on Coonrod Road had never been cut or subjected to any type of control. The tarps were also used on Merriam’s Forge
Road in order to compare continued cutting and herbicide on one patch, to tarp
treatment at another stand slightly to the north. The landowner had applied cutting and herbicide controls on both
sites the previous year.
BRASS
arranged for the Essex County Master Gardeners to dig 15 loosestrife plants for
raising a sufficient number of Galerucella beetles (provided by Cornell
University) to control purple loosestrife on the two properties in Willsboro
and Westport. And, BRASS prepared and
submitted the NYSDEC agency release permit application for the beetles, which
included stipulations for monitoring twice a year for five years the beetles’
impact on loosestrife. The release
permit was approved, and the beetles were released at the two private landowner
sites on July 15 with assistance from the Essex County Master Gardeners.
8- Assist towns and road
departments with laborers and volunteers for cutting/pulling/raking/ bagging
tasks. The Willsboro highway department
raked up and burned all old Japanese knotweed canes (as advised by APIPP) on
Coonrod Road, Fish & Game Road, and at the Memorial Park during the first
week of May. (Knotweed canes at
Noblewood Park were small and scattered, so prior burning was not
necessary.)
In mid-June, BRASS helped
the Willsboro DPW cut and bag the re-growth at the town’s knotweed sites,
pulled and bagged the garlic mustard at Noblewood Park, and worked with an
inmate crew in Westport to cut knotweed and pull garlic mustard on Merriam’s
Forge Road, and to cut knotweed behind the Westport town hall. Knotweed canes removed from the town hall
were put into a loader and removed from the site by truck to the Westport burn
pile. Canes and garlic mustard plants
from Merriam’s Forge Road were bagged and put into the landfill after
decomposition, as were the bagged knotweed and garlic mustard from Willsboro
sites. No volunteers were available for
these tasks as school was in session, most local adults able-bodied enough for
these strenuous tasks were employed, and Student Conservation Association’s
Americorps volunteers were committed to other APIPP projects.
A licensed herbicide
applicator from NYSDOT, who had worked on state road control sites, applied the
first herbicide treatment the same day knotweed plants were cut in Willsboro
and Westport. Knotweed stem ends, about
an inch above the ground, were wicked/swabbed with Garlonâ 4 mixture of 1 ounce Garlon/1 gallon
distilled water*, or Rodeoâ (if within 100 feet of water) in a 1-to-4
ratio of herbicide to water. (A
backpack sprayer was used behind the Westport town hall where the 10-member
inmate crew had stepped on and crushed too many stems, as well as at the
Willsboro Memorial Park where stem diameters were quite small due to repeated
mowing over the years.)
Tarps were pinned in place
by BRASS immediately following these activities at the Coonrod and Merriam’s
Forge Road sites.
A weedblock fabric was used
along the edge of Coonrod Road for a width of 4-feet, as it was less expensive
and could easily be replaced if snow plowing activity were to damage the
fabric.
BRASS
cut most of the Phragmites behind the Westport highway garage during the week
of July 5, with assistance from international volunteers. This was followed by an herbicide backpack
spray application of Garlonâ 4 by NYSDOT. (Due to the thick density of plants with
small stem diameters, the applicator felt spraying would be more effective than
swabbing.) Over the last decade, wood, metal,
and discarded machinery had been left in the Phragmites area, making cutting
extremely difficult and the herbicide treatment ineffectual. With encouragement from BRASS, the highway
personnel cleaned up and removed all discarded materials. In addition, a grader and back hoe created
a proper ditch to help dewater the site to discourage new Phragmites growth and
expansion.
9- Re-apply control implementation measures if
necessary and if the budget allows.
BRASS
was able to properly cut the Phragmites patches again at the Westport highway
garage the week of July 26, and herbicide was applied for the second time. Roundupâ was used for this
application as BRASS was reluctant to use Garlonâ again so quickly. (Garlonâ is a triclopyr broadleaf
herbicide, persistent in the environment, mobile in soil, with a half-life up
to 100 days, and it is believed Garlon has the potential to leach to ground
water. Even with the cut stem/swab
application, not all the herbicide is confined within the cut stalks; BRASS
believes there could be many drips as the applicator walks through a large
patch, and worries that as Garlon is translocated via cellular tissue to the
rhizomes it might leach into adjacent soil.)
All
sites were assessed thoroughly the week of August 23rd. Although Japanese knotweed densities had
been reduced by an average of 30%, new knotweed canes looked healthy and
vigorous. (Please note the controls
spreadsheed on the next page, and photo documentation of priority sites in Attachment
E.) The Phragmites in Westport appeared
nearly unfazed by the herbicide applications.
Half of the tarps were removed at Coonrod and Merriam’s Forge Road to
see if new growth had actually been smothered.
Knotweed plants at both sites were emerging, but less than one plant per
square foot, and when plant corkscrew growth (from the weight of the tarps) was
straightened the average size was but 5-6 inches. At Coonrod Road, the tarped knotweed roots had extended laterally
and were sending up healthy and dense 3-foot tall shoots around the north and
east perimeters. Very little lateral
growth was apparent at the Merriam’s Road site, where the landowner had cut and
applied herbicide the previous year.
Perhaps, if the summer had not been so rainy and cloudy, the knotweed
roots and new plant growth might have suffered more or been killed from the
sun’s heat collected under the tarps.
- On September 1st
and 2nd, BRASS hired a licensed applicator to apply another
round of herbicide. Roundupâ was swabbed onto canes
cut by BRASS that had grown 3-4 feet at the Fish & Game Road. The canes averaged 1/3
” diameter, there were approximately 8 stems/y2, and the
biomass cut was put into four 55-gallon 3 mil black plastic bags. (Sixteen bags were filled from this
site during the first control. But, comparison of biomass amounts cannot be used as a
measure of control success since canes will probably not be cut in the
exact stage of growth each time because herbicide application is so
weather dependent.) Smaller uncut
plant growth (of ~1’ height) near and under the guardrail was sprayed
experimentally with TriamineTM II, at the encouragement of a Riverdale
Chemical Company representative.
(TriamineTM II is a broadleaf herbicide often used along highway
right-of-ways.)
- Triamine was also
applied to plants at Noblewood Park that looked very healthy but had been
diminished by 40%.
- At Memorial Park, and
at the untarped Merriam’s Road site, Roundupâ was sprayed onto small plant re-growth
(maximum 1.5-feet in height).
- Knotweed was cut (~14
stems/y2, 1/2” diameter) at the Westport
town hall just as they were beginning to flower at 4.5-foot height filling
twenty-two 55-gallon bags (stems during the first control were not bagged;
they were burned), and stem ends were swabbed with Roundupâ.
- Phragmites canes at the
Westport highway department were sprayed with Roundupâ.
- Where tarps were
applied on Coonrod Road, all knotweed growing up at grommet holes and
around the base of cedar trees was cut by BRASS.
In the first week of October before any frost, all sites that had herbicide treatment received another application of Roundupâ by the licensed contractor (and Rodeoâ next to the river at Memorial Park), however this time the dosage was elevated to a 1-to-3 mixture of herbicide to water. Only the smaller patches of Phragmites, to the rear of the Westport highway garage lot, were sprayed because the large patch (where wood debris and discarded materials had been removed) was covered with wollastonite by the highway superintendent for winter traction and to reduce the risk of equipment picking up and carrying pieces of surfaced Phragmites roots and rhizomes.
Results:
So you have knotweed and want to be rid of it? . . . Even on a patch by patch basis, successful eradication is likely to take more than one year, let alone one treatment in most cases. (Jonathan Soll, Controlling Knotweed in the Pacific Northwest, The Nature Conservancy, Oregon, 2/2004.)
Results
from attempts to control Japanese knotweed on Willsboro and Westport’s priority sites
in one growing season are not heartening.
(Although judgment should be suspended until the spring and summer of
2005 when field investigations can count stem densities.) At best, it appears the sites subjected to
multiple herbicide treatments—whether stems were cut and swabbed or
whether small plants were foliar sprayed—saw only a 40% reduction in stem
densities. Sites subjected to tarps
appeared to fare better control results, although small seedlings were still
emerging under the tarps in the fall of 2004 (on the site with no prior
controls, average seedling growth was 6 seedlings per square yard; on the site
with prior herbicide treatment, 1 seedling per square yard). Please click here to see the control spreadsheet.
Results
from attempts to control Phragmites in Westport were even more discouraging. After two cuttings and three herbicide
applications (2 stem sprayings and 1 foliar spray), stem densities actually increased. Perhaps the choice of herbicide or application
strength was inappropriate. And/or the
multiple cuttings were not wise since Phragmites is a grass and will increase
in density and root mass with each cutting.
Results
from attempts to control garlic mustard and purple loosestrife cannot be determined
yet. Although BRASS pulled garlic
mustard at Noblewood Park in Willsboro prior to this grant, it can take up to
seven years of pulling the plants to exhaust the seed bed in the soil. The Galerucella beetles were released
as a loosestrife control in mid-July.
Monitoring for their impact will not begin until spring of 2005.
Additional
Comments: Even though there has been over a decade of
attempted Japanese knotweed controls throughout the country, there is
relatively little pre- and post-comparative documentation whereby exact control
protocols used over time on specific plot sizes, stem
densities
and stages of growth are described. In
particular, there is little documentation of these items in this geographic and
climatic area. The Adirondack Nature
Conservancy’s (ANC’s) Invasives Project Field Coordinator, Steven Flint,
believes assessment and choice of control are dependent upon the geophysical
setting of each individual infestation, and that results from even identical
treatments may vary between target sites.
Therefore, ANC staff monitor and assess efficacy of primary controls
implemented—a principal of adaptive management strategy. Secondary controls are determined by the
effectiveness, or lack of, the primary control.
In
2003, the favored herbicide control* of
Japanese knotweed in the Adirondack Park by APIPP’s ANC was a cut-stem
treatment. Canes were cut and herbicide
(principally Garlonâ 3A**,
a salt-based triclopyr) was immediately swabbed or sprayed onto and directly
into the freshly-cut cross-sections via a “swiper” (a long handle with screw-in
herbicide bottle at the top and a cellulose sponge at the bottom) or a
commercial-grade “Windex” low-volume spray bottle with an adjustable
nozzle. The mixture of herbicide (out
of the container) to water was generally one-to-four.
When
the NYSDOT licensed herbicide applicator applied the first treatments to
knotweed in Willsboro and Westport, BRASS assumed the herbicide and mixture
rate would be the same as APIPP’s ANC method.
(NYSDOT is a principal partner of APIPP, and they have applied controls
with ANC along several state roads in the Park.) Instead, Garlonâ 4 was used in a mixture
with water at 1-64.*** No doubt this weaker mixture resulted in
more Willsboro and Westport cane re-growth compared to stands treated by ANC in
2003 at other Park locations.
In
June of 2004, while control managements were underway on the Willsboro and
Westport priority sites, APIPP’s ANC began experiments with a facsimile to
herbicide injection on ten Japanese knotweed and Phragmites stands in the
Adirondack Park. Trials in herbicide
injection in the Pacific Northwest by The Nature Conservancy were showing
great promise, reporting during 2004 an astounding 100% eradication of knotweed
canes when injecting 5ml of 100% Roundupâ Pro, a salt based
glyphosate, into each stem of a knotweed clump. An injection tool was even manufactured for this purpose by JK
International Injection Toolsâ. Although APIPP’s ANC did not use the injection tool due to cost ($220)
and permit (NYSDEC does not permit herbicide injection as herbicide companies
have not yet put it on their labels, and “the label is law”), Steven Flint used
the next best instrument—a Nalgene wash bottle with a leakproof, angled, squirt
tip. For these applications, a
one-to-one mixture of 15 ounces Garlonâ 3A-to-15 oz. distilled
water was used, with an additional ounce of Cide-kick II as a surfactant to
help break down cell wall membranes.
Steven Flint believes he has been successful at 100% eradication with
this method at specific target sites, although it will require ongoing
monitoring throughout the 2005 field season to determine the ultimate efficacy
of this control method.
This
one Garlonâ 3A-to-one water solution
was applied on July 1 to part of a knotweed patch on Merriam’s Forge Road in
Westport owned by the Adirondack Nature Conservancy, just ¼ mile north of the
two town priority control sites. Steven
Flint first cut the canes, then squirted the solution into the hollow stem ends
(two squeezes, or about 7-11ml.), and with the other gloved hand wiped any
spill onto the outside stem. Throughout
the summer and fall, no new stems appeared on this treated section. Whereas, on the Willsboro and Westport
knotweed priority sites, herbicide treatment (whether Garlonâ 3A, Roundupâ, or Rodeoâ at a reduced mixture rate, beginning in mid
June) only resulted in some control of stem densities and plant
robustness. Native plant species,
previously intermixed with the knotweed, continued to grow.
If
there is no further Japanese knotweed stem growth in 2005 at APIPP’s ANC
Merriam’s Forge Road control site, one might conjecture: 1) the 1-to-1 Garlonâ 3A mixture appears to show promise as a
method of eradicating Japanese knotweed; 2) and/or the surfactant is possibly a
necessary mixture ingredient; 3) and/or waiting until July 1 for herbicide
treatment is crucial; or 4) all--or any combination of--measures is the key.
In
terms of cost efficiency, even including the injection “gun” applicator cost
($220) and with Garlonâ 3A and the surfactant about
one-third more expensive than the other herbicides, the injection method could
be the cheapest scenario given the high cost of labor for multiple herbicide
treatments. (For some sites subjected
to herbicide treatment, careful restoration of native vegetation may require
yet more funds.)
Despite
the cost efficiency, there should still be some underlying concerns: 1) the length of time Garlonâ is persistent in the environment at half the
strength from the container; 2) whether wildlife would be affected; 3) what
warnings might be necessary along public road right-of-ways or public access
sites; 4) if there is a possibility of the herbicide moving into groundwater,
especially given the geology and soils of particular sites; 5) how long it will
take native plant species—even if purposefully planted—to reclaim the area, or
how much landscaping with additional soil may be necessary; and 6) how many
plant stands within a certain radius should receive this treatment in the same
year or within several years’ time for all the reasons stated in 1-5
above. In addition, Garlonâ cannot be used when invasive plants are in
or near water, so effective controls must still be found for stands along
rivers and lakes.
Tarps
may still prove viable and efficient in certain locations, according to data
thus far from the Westport and Willsboro sites, despite what is reported by
Jonathon Soll at The Nature Conservancy in Oregon:
There are multiple anecdotal reports of control attempts using
extended covering, but no reliable reports of successful knotweed control with
covering. This includes those of the
Lummi Nation in Washington, who combined digging, tilling and covering with
several layers of cardboard on 2, ¼ acre patches. The results were poor however; they achieved only 80% reduction
in stem number at a cost of $32,000/acre. . . TNC also failed to achieve good
control covering a single large patch for about 6 weeks in the spring. Others have also reported that knotweed
grows out from under the covering material.
If you must try it, this method is likely to work better with isolated
and smaller patches on open terrain. . . (Soll, page 6.)
Tarps
used by BRASS cost from $1- $2/sq. yd. depending upon the size ordered. Plus there is the labor of cutting and
bagging material before application, disposal cost of the bags at a landfill,
and the labor of applying the tarps and cost of ground pins. If the tarps hold up over a winter, and if
there is no new stem development underneath the tarps the second year, this
could become the preferred control method where herbicide cannot be used, and
possibly even where herbicide can be applied.
The Coonrod Road tarp site in Willsboro is an area of 275 square
yards. Tarps, soil pins, and material
disposal cost $302, and the labor of cutting and bagging would bring the total
to around $350.
When
comparing the cost of stem injection versus tarps, tarps appear far more
cost effective. Let’s assume a seasoned
herbicide applicator can inject 2-4 knotweed stems a minute (not an easy chore
maneuvering through a dense patch).
With an average of 15 stems/sq.yd. at the Coonrod Road site, the total
number of stems were 4,125. With that
number of stems, it would take an herbicide applicator from 1000-2000 minutes
or 17-33 hours for stem injection.
Licensed herbicide applicators typically charge $50/hour. At the minimum 17 hours, the charge for the
herbicide applicator would be $850 plus the $220 cost of the stem
injector. Therefore, at 33% of the cost
of stem injection, tarps could be applied with little or no environmental
impact. If only 2 stems can be injected per minute, the cost
of tarps would only be 18% that of stem injection.
Even
if tarps prove effective by the summer of 2005, there is still the issue of
lateral growth beyond the tarps. When
tarps were pinned at Coonrod Road they were extended only a couple of feet
beyond the concentrated area of Japanese knotweed stems. (It would have been very difficult for BRASS
to tarp among and between the black willow trees growing to the north in a
large ditch/swale area.) Knotweed roots
have been known to spread laterally over 20 feet, and they certainly moved
laterally at the Coonrod Road site.
Therefore, any cost comparisons should include extra square yards of
tarp to prohibit lateral growth (assuming site conditions allow for this
extension). At Coonrod Road, if the
landowner had cut down all trees so the tarps could be extended, the cost of
tarps would be 40% of stem injection at 4 stems per minute.
If
tarps could not be extended due to landscape features, mowing would be
necessary to control knotweed from spreading back into the tarped area. Mowing raises yet another issue. According to Jonathan Sol, mowing will
actually stimulate the production of shoots from latent buds. TNC, he says, was able to control one small
patch with 25 stems by 17 monthly cuttings over three years.
So, unless you are prepared to cut knotweed patches TWICE
A MONTH OR MORE – could we say it any stronger? – especially between April and
August, and then once a month or more until the first frost, a program based on
cutting alone is likely to be a recipe for frustration and failure. (Sol, page 6.)
What
are future options at the Willsboro and Westport control sites?
Fish & Game Road: Two opportunities seem promising: tarps or stem injection. Japanese knotweed growth previously covered a road sign. Eradication of knotweed on this site, therefore, is needed to assure road safety. Because of a guardrail and sloping site profile, highway mowing is not an option. Indeed, given the above quote, road departments would never have the time to mow twice a month or more, therefore the stem injection or tarp choices. It would be wise to include the landowner, across the road, in future control efforts. Japanese knotweed is growing as ornamental plants on two locations near the house. More stems have appeared near the road on this property, but they are obviously kept cut by the landowner. Perhaps the deep pile of leaf and stem debris along the slope of the control site is cut material deposited there by this landowner. (Estimated future costs for control: $80-$150 for tarps and pins, plus additional money for reseeding. If stems remain around 8/sq. yd, stem injection would cost ~$115-$230, without cost of the injection tool nor money for removing dead plants and replanting).
Coonrod
Road: Tarps will stay on this site at least into
the summer of 2005, but only to test the efficacy of the tarp method. (Heavy tape should be applied to the grommet
holes to make sure no emerging seedlings under the tarp are from still viable
stems that kept squeezing through the holes during 2004.) But, due to the knotweed around the north
and east perimeters, the knotweed growing in the cedar tree hedge near the
road, and the fact that the site is inappropriate for herbicide use, the only
avenue seems to be highway mowing at appropriate times to keep the road sign
from being obscured unless the landowner is willing to cut all cedar and black
willow trees in order to extend the tarps.
When the tarps are removed, the site should be reseeded. (Estimated future costs: $50-$100 every year for mowing in early June
when departments are not mowing elsewhere.)
Memorial
Park: Again, tarps or stem injection may prove the
best scenario. Because of the location
in the center of town, and immediately adjacent to the memorial stones, tarps
may not be deemed appropriate. Stem
injection would have to be very well timed—probably in August—when it is hot,
dry, and no rain forecast, so that herbicide translocated into the roots will
not enter the river should the water rise significantly over some of the
knotweed situated near the bank.
Otherwise, perhaps Rodeoâ can be injected on those
stems at a mixture stronger than 1-4.
(Estimated future cost: Stem
injection for 80 sq. yds. with 16 stems/yd., would be $270-$535 without the
injection tool, plus cost of removing dead plants and reseeding.)
Noblewood
Park: Eradication of the knotweed at the primitive
tent site area should be a priority as it appears to be spreading down the
hillside toward the wetland and floodplain.
Along the hillside, perhaps every effort should be made in early spring
to try to pull the plants. (Forest duff
and wet weather may make it possible to pull out--and at least reduce--many of
the roots and rhizomes. Tarps are not
possible given so many trees, but stem injection is a possibility, especially
if the issues of concern (listed at the top of page 9) are resolved. Otherwise, the Willsboro Department of
Public Works should repeatedly cut down and remove all shoots every couple of
weeks. High school student park
stewards, hired during the summer by the town, could carry on this duty
throughout the summer. They should be instructed
not to throw any brush over the hillside that would inhibit their ability to
cut the knotweed. If repeated cutting
is used, perhaps the forest canopy might begin to shade out the knotweed within
a few years. (Estimated future
cost: Stem injection would be perhaps
$25 if the applicator already owned the injection tool.)
Behind
the Westport Town Hall: Again, either tarps or stem
injection appear the best choices.
Since 99% of the knotweed stems are on private property, the private
landowner must make the decision and probably carry the expense burden unless
additional grant funds become available.
Currently the landowner very much desires a strong vegetative border
(like knotweed), or a fence, to remind persons utilizing the town hall that the
land is private property. (Estimated
future cost: Tarps would be $300-$600; the cost of a split rail fence
~$75. Stem injection for 286 sq. yds.
with 14/stems per square yard would be $830-$1,665 plus cost of reseeding.)
Merriam’s
Forge Road (northern most section): The site
is a good candidate for stem injection.
Even though the landowner is so desirous of knotweed eradication he may
mow more than twice a month, large stones would have to be moved and tons of
soil brought in to allow mowing. The
same care must be taken as at the Memorial Park in Willsboro if stem injection
is utilized, to reduce the risk of herbicide entering the Boquet River. Garlic mustard should continue to be pulled,
bagged, and when liquefied put into the landfill. (Estimated future cost:
At 6 stems/sq. yd. for a 300 sq. yd. area of Japanese knotweed, stem
injection would cost $375-$750 plus reseeding.)
Merriam’s
Forge Road (southern tarped section): Tarps
should remain at least until mid-summer of 2005. Any knotweed stems appearing along the tarp edges in 2005 could
be treated to stem injection. Then the
site should be vegetated with grass, forbs, and fast-growing tree seedlings.
Westport
Highway Garage: Several control options might be considered,
all experimentally: 1) Stem injection
of Phragmites, which APIPP ANC’s field coordinator experimented with in other
areas of the Adirondack Park in 2004.
Phragmites stems are more numerous per square yard than Japanese
knotweed, so this method could be expensive.
2) Changing salinity conditions (Phragmites does not appear to survive
with salinity above that of marine wetlands), and
3)
disking (to surface and allow removal of root and rhizome mass), are two
suggestions from invasive plant research (Diana H. Cross &I Karen L.
Fleming, Control of Phragmites or Common Reed, US Fish & Wildlife
Service, leaflet 13.4.12). 4) Tarps
might be considered, at least in those areas where there will not be movement
of highway vehicles and equipment. (Estimated
future cost: Stem injection on the
whole 258 square yards with 27 stems/sq. yd. would amount to
$1,470-$2,950.) At the very least,
purple loosestrife should be cut by mid-July, bagged, and properly disposed of
after liquefying. Any additional
plants, with blooms appearing after mid-July, should also be cut. Optimally, since the density of loosestrife
plants is light and scattered, a spot application of Rodeo at a 2-5% mixture as
flowers are blooming might control the infestation, especially if re-applied
during the next several years to take care of any seed re-growth.
Two
purple loosestrife sites: The Paine property in
Willsboro, and the Sherman property in Westport, will be monitored by BRASS in
spring and fall of 2005 for the impact of the Galerucella beetles. Given results from the spring monitoring,
advice should be given to the landowners about whether/when fields can be mown
without unduly disturbing the beetles.