**[INTEGRATED PEST MANAGEMENT PLAN]{#BM_2_}**

**Maxwell National Wildlife Refuge**

** Colfax County, New Mexico**

** Written and Revised in 2002 by**

** Daniel R. Dinkler, Invasive Species Biologist**

**Edited by**

# Dr. Elaine Snyder-Conn, National Pest Management Coordinator

***Approvals and Concurrence***

Maxwell National Wildlife Refuge:

***Project Leader***

Signature Date

Southwest Regional Office:

***National Wildlife Refuge System***

***Refuge Supervisor, Arizona & New Mexico***:

Signature Date

***Invasive Species and IPM Coordinator***:

Signature Date

***Regional Contaminants Coordinator***:

Signature Date

Washington Office:

***National Pest Management Coordinator***:

Signature Date

## INTEGRATED PEST MANAGEMENT PLAN

Maxwell National Wildlife Refuge

Colfax County, New Mexico

**Introduction**

The following is a comprehensive Integrated Pest Management (IPM) Plan
for controlling or eliminating key weed and insect pests affecting
Maxwell National Wildlife Refuge trust resources and to meet our
compliance needs with State and Federal noxious and invasive species
laws. This plan is developed under the authority of the Federal Plant
Protection Act of 2000, the Federal Noxious Weed Act of 1974, Executive
Order 13112, the Refuge Administration Act of 1965, the Refuge
Improvement Act of 1997, and the New Mexico Noxious Weed Management Act
of 1998, and is in following with the requirements of the Refuge Manual
for the National Wildlife Refuge System (7 RM 14). This plan is also
intended to address recent Director\'s priorities to control invasive
species in the refuge system\'s \"*Fulfilling the Promise*\" document
and related work group efforts.

Invasive and noxious weeds at Maxwell Refuge have already reduced
wildlife habitat and biodiversity and are infesting neighboring lands.
Not only are these invasive plants problematic on the refuge and across
refuge boundaries, but when a cooperative farmer exports products off
the refuge, such as alfalfa hay, and that hay contains invasive weeds,
that hay can infest other off-refuge sites, providing a botanical
version of "typhoid Mary". Such transport can also occur by wind or
water, or by seed transport on farm or other equipment or the thousands
of visitor vehicles traveling on and off the refuge. Obviously, these
are not the kind of contributions to the ecosystem expected from our
national wildlife refuges.

Maxwell Refuge recognizes the special importance of immediate and
long-term attention to its invasive weeds based on the "3:1 principle"
that for ***each year*** a treatment is delayed, it will take an
***additional three years*** to achieve the same level of control. That
numeric value of "times three" applies to the increased labor and other
costs, as well as to the volume of herbicides needed, if effective
treatments are delayed. Thus, treatment costs can increase geometrically
by delaying an effective control program . With this IPM Plan, Maxwell
Refuge aims to demonstrate land stewardship in controlling invasive
plants and other pests, while striving toward the goal of restoring
native habitats and fauna, thereby re-establishing the health of the
refuge ecosystem. The Director's Priority for invasive species also
elevates the control of invasive species on all units of the refuge
system to a high priority.

By definition, a weed is an unwanted plant, wherever it occurs. On
Maxwell Refuge, insect and weed pests are common in and around farm
fields. Numerous exotic plant species considered noxious or invasive in
New Mexico are well established on Maxwell Refuge, competing with native
plants for sunlight, water and nutrients, and jeopardizing the ability
of the refuge to provide habitat for migratory birds, which is the
primary purpose of the refuge. While many weeds establish by pioneering
on disturbed sites, and are eventually followed in succession by native
species, Maxwell Refuge also hosts a variety of more insidious, exotic,
noxious plants termed "***invasive***." Such invasive plants are not
only effective at pioneering disturbed sites, but they also proliferate
to the exclusion of native plants, interrupting the natural process of
plant succession and permanently dominating the vegetative communities
in the absence of natural biocontrols from their original source
locations. Once established, invasive species can have a dramatic,
negative impact on ecosystems. Millions of acres of the western
landscape have rapidly been taken over by single invasive species, with
yellow starthistle and leafy spurge providing two of the worst examples.

In the plan, we present IPM treatments selected to control pests
according to the refuge's various site and soil types, with attention to
resource needs. Both pesticide and non-pesticide control methods are
considered, specific to each pest species, as are mapping, monitoring
and prevention methods. Previous experiences in controlling pests are
also described, so that only methods that are likely to be effective in
the future are used. If there are sensitive resources present at some of
the sites, such as rare or listed species or other species of concern,
limiting treatment options, these resources and their locations are
discussed and low-risk treatment options are selected to protect the
sensitive species or sites. For example, if an infestation is adjacent
to a perennial water source and a herbicide treatment would likely
contaminate that water, then that treatment option would be
inappropriate at that site. Similarly, a broad-spectrum herbicide would
be inappropriate unless it was used as a spot treatment only on the pest
in question and precautions are identified to reduce drift, leaching,
and runoff to sensitive areas nearby. In many cases, more than one
invasive weed species is present on a site. In these instances,
treatments are designed to treat the highest priority invasive plant
species. This plan recognizes that pest control, and particularly
invasive species control, will require a multi-year commitment, with
follow up monitoring, assessment of the successes and failures of
treatments, and development of new approaches when proposed methods
fail.

**Site Description**

Maxwell National Wildlife Refuge is situated in northeastern New Mexico
near the western edge of the historical shortgrass prairie and just east
of the Sangre de Christo Mountains (Figure 1) very near the historic
Santa Fe Trail. Situated in the watershed of the nearby Canadian River,
Maxwell Refuge falls into the Arkansas-Red River Ecosystem and is
administered through the U.S. Fish & Wildlife Service's (Service)
Southwestern Regional Office located in Albuquerque, New Mexico. The
Refuge encompasses 2,792 acres of habitat acquired in fee title. Located
in the highlands with elevations in the range of 6,100 feet, the
topography includes areas that are almost flat interspersed with gently
rolling, low hills, creating some sinks and playas, the largest of which
have been converted to irrigation reservoirs that are owned and managed
by the Vermejo Conservancy District.

***Refuge History - ***Land acquisition for Maxwell NWR was initiated in
1966. Historically, lands that today comprise the refuge supported
shortgrass prairie. Grassland plant communities included associations
dominated by blue** **gramma (*Bouteloua* *gracilis*), and alkali
sacaton (*Sporobolus* *airoides*), with buffalograss (*Buchloe*
*dactyloides*), western wheatgrass (*Pascopyrum* *smithii*), fourwing
saltbush (*Atriplex* *canescens*), alkali muhly (*Muhlenbergia*
*asperifolia*), and inland saltgrass (*Distichlis* *spicata*) also
common. The development of the first irrigation system in the area,
which diverted water from the Vermejo River, dates to the late 1880\'s.
Scattered ranches with farming operations sprouted up and livestock
grazing increased with the availability of water for stock tanks and the
irrigation of crops. Along with introducing cattle** **and numerous
weeds, settlement of the area frequently included planting Siberian elm
(*Ulmus* *pumila*, a.k.a. Chinese or Russian elm) to provide shelter
belts around areas of habitation. Limited farming continues on the
refuge, but livestock grazing was terminated in the late 1960\'s as
lands were acquired**.** Farming and grazing activities, along with the
development of the irrigation system infrastructure, have altered most
of the habitat on the refuge.

***Habitats -*** Refuge habitats include former pasture (referred to as
range in this document), farm fields (both in use and abandoned), playa
lakes and surrounding alkali flats, irrigation reservoirs and associated
wetlands, and several wooded thickets associated with former home sites.

In 2000, 371 acres were under cultivation, with the majority of those
acres farmed under cooperative agreement with two local farmers. The
remaining acres were farmed directly by the refuge. Crops grown include
alfalfa, which provides a significant amount of green browse for
migratory birds during the migration and wintering seasons, and "hot
foods", or grain crops, that sustain birds and other wildlife in the
cold of winter; typically barley, wheat or corn grown by the refuge or
under cooperative farming agreements. In excess of 500 acres of
previously-farmed and now-abandoned farm land await restoration to
native prairie. Most the remainder of the refuge's 2,792 acres have been
altered by historical grazing, but never broken out and farmed, largely
due to their location on inferior, saline soils. These grazed areas
would also benefit from restoration, but the abandoned farm fields are
better candidates for restoration due to their location on better soils
and having better access and, in some cases, irrigation capability.

Three irrigation reservoirs, identified as Lakes 12, 13 and 14, are
located within the refuge, predate establishment of the refuge, and are
considered permanent reservoirs. These reservoirs, and the surrounding
land, are owned and managed by the Vermejo Conservancy District
(District), with the District managing the water levels. Lake 13 is a
very popular angling site for stocked trout and catfish, attracting
thousands of vehicle-based visitors annually. Numerous irrigation
ditches, either owned by the District, or operated by the District as
rights-of-way, cris-cross the refuge, feeding the reservoirs and
delivering water to area farmers. With the development of these
reservoirs substantially more water currently exists on the refuge
landscape today than was there historically. The reservoirs hold water
all year, although water levels (and shorelines) vary with precipitation
and irrigation demands.

With hundreds of acres of dammed-up standing water in the reservoirs,
the water table in the vicinity of the dams is affected, creating moist
soil conditions below the dams in some localized sites. The
proliferation of irrigation ditches, both for inflow to supply the
reservoirs and for delivery to area farms, creates seasonal open water
areas and about 70 acres of cattail wetland and another 43 acres of
rush/sedge wetland. These open water and wetland sites are sensitive
areas which are important considerations when planning for the
application of herbicides to the refuge landscape. The refuge has
management agreements for about 900 acres of District-owned lands
surrounding Lakes 12 and 14, bringing the total area managed by the
refuge to about 3,700 acres.

Other sensitive areas that are largely seasonal in nature are water
delivery canals and ditches that bring water into and out of the
reservoirs, and seeps that develop below dams due to the hydraulic
pressure exerted by standing water behind the dams**. **Also, heavy
rains can create temporary standing water in low lying, poorly drained
sites for short durations.

***Roads* -** Several unpaved roads provide vehicle access around and
through the refuge, primarily on section and half-section lines. The
roads themselves, and disturbed sites next to the roads, provide
important weed habitat and transportation corridors. Most roads are
gravel Colfax County right-of-ways passing through, or along, Refuge
borders. State Highway 505, a paved asphalt road, runs along the
Refuge's southern boundary. The refuge owns and manages two miles of
unpaved road, and manages the public access roads at Lakes 13 and 14
under agreement with the District. Road composition affects the
likelihood of vehicles and equipment picking up and transporting seeds
in mud, aiding in the distribution of invasives. The identity of each
road's managing agency will be important in coordinating weed management
activities, such as the timing of mowing.

***Soils*** - Soils on Maxwell NWR are deep silty clay loams derived
from the Cretaceous shale and deposited by alluvial and eolian
processes. The more lowland soils fall into the Vermejo soil series and
the upland sites are represented by soils from the Swastika Series. The
silty clay loams of the Vermejo Series are easily erodible and often
high in salts. The silty loams and silty clay loams of the Swastika
Series are also high in salts, but somewhat less erodible in comparison
to the Vermejo Series. Both soil series are relatively low in organic
matter and high in salts and pH (i.e., they are alkaline). Low lying
sinks and the margin of playas are characterized by the presence white
alkali and are virtually barren of vegetation.

Most of the farm fields and range sites are dominated by soils with high
clay content, such as the Swastika-Colmor clay loam. These soils
typically do not drain well due to their high clay content, and
translocation of pesticides through the soil profile into the water
table could be expected to be minimal. The rolling topography offers
gentle slopes, with runoff minimal in combination with scant amounts of
moisture normally received in any precipitation event. There are no
geological outcrops that provide sandy or gravely substrate anywhere on
the refuge. Additional detail on soils and their location are available
from the Colfax County Soil Survey and in the refuge files.

***Climate -*** Due in part to elevation, the climate is dry and cool,
with a short growing season of only about 120 days. Precipitation is
typical of the Southwest, averaging about 14.5 inches. Precipitation
events can be quite variable, with summer showers not uncommon,
depending on how well developed the summer "monsoon" season is. As with
any thunderstorm activity, rainfall amounts can vary drastically over a
short distance within the refuge. Included in the annual precipitation
total is snow melt, with snowfall averaging about 17.5 inches, providing
about two inches of water when melted. ** **

**Paste Map Here. If possible, include some of the field locations.**

High winds are not uncommon, especially during storms and in spring, and
particularly in March and April. Late spring and summer mornings often
begin with calm or light winds, typically changing to a southerly breeze
as the day warms. Southerly winds that easily exceed the limits for boom
spraying frequently prevail in the afternoon.

***Sensitive Refuge Sites and Species -*** Sensitive areas on the refuge
include the following:

-   the permanent water found in irrigation reservoirs 12, 13 and 14.

-   seasonal water flowing in irrigation delivery and inflow ditches.

-   moist seeps, dam faces & roadside ditches, when standing surface
    water is present.

-   susceptible crops, such as alfalfa and the clover mix used for
    rest/rotation.

-   the two black-tailed prairie dog towns (candidate species - see map)

-   range sites with dense nesting cover during the nesting season.

-   public use areas (primarily the dam at Lake 13) and roads.

-   a 80-acre Research Natural Area in the southwestern corner sited
    around the playa lake located adjacent to State Highway 505 (no
    special prohibition on controlling invasives).

A Section 7 Consultation covering black-tailed prairie dog towns was
prepared and approved in 2001. Since there are no invasive infestations
in or adjacent to either town, no conflicts with herbicide treatments
are expected, and any insecticide application (for grasshoppers) will
use a one quarter mile buffer from either town.

Two native thistle species, wavyleaf or silver thistle (*Cirsium*
*undulatum*) and yellowspine (*Cirsium* *ochrocentrum*) occur on the
refuge. Wavyleaf thistle is a common, widely distributed perennial with
leaves grossly similar to musk thistle in appearance in early growth
stages; yellowspine is a uncommon biennial or short-lived perennial with
a very limited distribution on the refuge.** **

***Drinking and Irrigation Water - ***Historically, there were domestic
ground water wells on the refuge. However, the refuge currently gets its
domestic water from the City of Maxwell and irrigation water from the
District, either from Stubblefield reservoir or Laguna Madre. There are
currently no wells pumping groundwater from anywhere on the refuge.

***Surrounding Land Uses* - **The major industry and source of income in
Colfax County is agriculture based, with cattle ranching predominating.
Ecotourism is also an important and growing segment of the economy. Much
of the open rangeland in the area is grazed, and growing alfalfa for hay
to feed cattle and horses is an important component of the local
agribusiness. To the extent that invasive species become established on
rangeland and in fields and take over the landscape, the ability of that
range and field crops to support livestock operations can be stressed
beyond the already thin margin of economic viability that most
operations run on in the arid New Mexico highland plains. Because of the
short growing season, any form of competition from an infestation can
adversely affect economic viability.

**TABLE 1. BROADLEAF WEED SPECIES ON MAXWELL NWR**

Priority invasive weed species are denoted by an asterisk (\*). These
invasive species are considered to present the greatest threats to the
refuge environment.

**\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**

** Common Name (+) Scientific Name Synonym Comments/Locations **

[\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_]{.underline}

field bindweed (C) Convolvulus *arvense* perennial morning glory
prolific, perennial

yellow sweetclover *Melilotus* *officinalis* yellow clover prolific,
winter annual

common cocklebur *Xanthium* *strumarium* common in fields, annual

spiny cocklebur *Xanthium* *spinosum*^1^ ** **C6 (1 plant found),**
**annual

\*hoary cress (A) *Cardaria* *draba* whitetop B5, F1 and various,
perennial

\*Siberian elm (C) *Ulmus* *pumila* Russian elm scattered groves

curlycup gumweed^2^ *Grindelia* *squarrosa* rosinwood rangeland,
biennial or perennial

scarlet gaura^3^ *Gaura* parviflori velvety gaura farm fields, biennial
or annual

halogeton *Halogeton* *glomeratus* Scattered, disturbed sites, annual

horseweed**^3^ ** *Conyza* *canadensis* rangeland, annual

\*Russian knapweed (B) *Centaurea* *repens* several patches, perennial

kochia * Kochia* *scoparia* prolific, annual

prickly lettuce * Lactuca* *serriola *China or wild lettuce common,
biennial or annual

locoweed (3 varieties) *Oxytropis* *spp.* crazyweed common in range
sites, perennial, poisonous to ungulates

Venice mallow *Hibiscus* *trionum* rosemallow farm fields, annual

common mallow *Malva* *neglecta* buttonweed farm fields, annual,
biennial or perennial

common mullein *Verbascum* *thapsus* various, biennial

\*Russian olive (C) *Elaeagnus* *angustifolia *planted at refuge
headquarters

common ragweed^3^ *Ambrosia* *artemisiifolia* prolific in fields, annual

\*saltcedar (C) *Tamarix* *ramosissima* scattered sites

spiny sowthistle *Sonchus* *asper* Common, annual

broom snakeweed^2^ *Gutierrezia* *sarothrae* broomweed overgrazed sites,
perennial

\*bull thistle (B) *Cirsium* *vulgare* dams, ditches, biennial, deep tap

\*Canada thistle (A)* Cirsium* *arvense *widespread, perennial and deep
rooted

\*musk thistle (B) *Carduus* *nutans* widespread, biennial or annual

Russian thistle * Salsola* *iberica* tumbleweed widespread, annual

yellowspine thistle ^2^ *Cirsium* *ochrocentrum * limited to**
**stackyard behind headquarters

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^1^ new in 2000. Exactly one spiny cocklebur plant was found in 2000
near the southwest corner of cooperatively farmed field C6.

^2^ a native plant but undesirable as forage and/or unpalatable or
poisonous to livestock and possibly some wildlife

^3^ native to U.S. but proliferates in disturbed sites and grain crops.
Horseweed is a nasal irritant to horses.

\+ Class A, B, or C weed based on New Mexico Noxious Weed Management Act
1998 (see definitions Page 8).

**Pests**

***Plant Pests* - **The Refuge conducted an intensive field scouting
program in 2000 and 2001 to identify nonnative species on the refuge and
map their locations as a necessary first step in the development control
strategies and this IPM Plan. Field scouting revealed numerous
infestations on the refuge. In addition to prolific infestations of
hoary cress and Canada, musk, and bull thistles on the refuge, scouting
forays in 2000 during the bloom revealed numerous Russian knapweed
infestations on and adjacent to the refuge, especially along roadsides.
Table 1 provides an extensive (but likely incomplete) list of exotic
plants and other weeds established on Maxwell Refuge. Based on survey
results and an assessment of threat and likelihood of effective control,
the Refuge will focus control efforts on the following priority species:
Russian knapweed; Canada, bull and musk thistles; hoary cress; Russian
olive, saltcedar, and Siberian elm.

The selection of these priority invasive species was based on the rapid
expansion capabilities of Russian knapweed, Canada, musk and bull
thistles, and hoary cress in the refuge and their potential adverse
impacts to farm and/or grasslands, including the toxic and allelopathic
effects of many of these invasives (see following individual biology
accounts). Also, Russian knapweed, Canada thistle, hoary cress, Siberian
elm and saltcedar can form dense monospecific stands, suppressing crop
yields and excluding native species. Prior to 2000, established
saltcedar trees were uncommon, but a large invasion of seedlings erupted
following the flood of May 1999 but did not become visually evident
until 2001. Saltcedar exudes salts that are phytotoxic, drastically
lowering species diversity where it occurs. In addition, saltcedar
alters hydrology and has enormous water use as high as 200 gallons per
tree each day, or more. As a result, there is less water and decreased
biodiversity wherever saltcedar becomes established. There is typically
a loss of both plant diversity and wildlife diversity as monospecific
stands of saltcedar replace native species, a serious problem in
riparian areas off the refuge and throughout the southwest. Russian
olive and Siberian elm, like saltcedar, also present similar serious
environmental threats.

In the New Mexico Noxious Weed Management Act of 1998, the New Mexico
Department of Agriculture has identified offending invasive species in
the State as either **Class A, B or C** noxious weeds. Class A weeds
occurring on the refuge include Canada thistle and hoary cress, while
Russian knapweed and musk and bull thistles are identified as Class B
weeds. Class C weeds found on the refuge include field bindweed,
Siberian elm, saltcedar and Russian olive. Class A weeds are given the
highest priority towards prevention and elimination in the state of New
Mexico, and Class B, the second highest priority. We therefore plan to
cooperate fully with the county and State in working to eliminate these
weeds from the refuge, although our strategies may sometimes differ,
depending on the occurrence of sensitive plants and wildlife on the
refuge.

Three important invasive species on Maxwell Refuge, not herein selected
as priority species, are field bindweed, yellow sweet clover and kochia.
Field bindweed could easily be included in the priority list if it were
not for how well established and widespread it has become, making
control with herbicide unrealistic and elimination virtually impossible.
About the best manageable result that can be expected for bindweed is
partial control or suppression in crop fields, although yet-untried
biocontrols may hold some promise. Yellow clover, planted in refuge
fields as part of the rest rotation cycle, has escaped and is also very
well established in fields and range sites. Similarly, kochia is also
very common in fields and ranges sites and would be extremely difficult
to control.

Several other invasive species on the refuge would immediately become
priority species and treated or uprooted immediately if identified,
including yellow starthistle and leafy spurge. Leafy spurge is
established in at least three sites in Colfax County, and seeds from
yellow starthistle and numerous other invasive species infestations are
just a few hours drive up Interstate 25 in Colorado and Wyoming, waiting
to hitchhike a ride over Raton Pass to Maxwell, New Mexico. In addition,
weed species such as common mullein and halogeton will be suppressed on
an opportunistic basis, especially when co-located with other weeds.

Minor weeds with lower rates of spread were also not identified as
priority weeds. Only a few individual yellowspine thistle plants were
discovered in 2000 in the cooperative farmer's stack yard behind
headquarters, after flowering, perhaps demonstrating a late season
growth habit.** **Russian thistle is a minor agricultural pest,
preferring disturbed sites, and will be controlled incidentally to other
farm weeds. Additionally, exactly one spiny cocklebur plant was
discovered in 2000 near the southwest corner of cooperatively-farmed
field C6. In addition to the above broadleaf "weeds", there are also a
variety of non-native grass species, including smooth brome (*Bromus
inermis*) that are less well-known as to their identity, distribution
and the degree of their threat potential. Continued scouting with
additional training on grass identification will enable the refuge to
study possible control needs for grass species.

**TABLE 2. DOMINANT GRASSHOPPERS IN MAXWELL NWR CROP AND RANGELANDS FROM
1988-1990.**

Bomar, et al (1993) identified the following common grasshoppers on the
refuge in 1988-1990:

Spurthroated grasshoppers (Melanoplinae):

*Melanoplus* *bivitattus* \*two-striped grasshopper

*M*. *femurrubrum* \*redlegged grasshopper

*M*. *lakinus* Lakin grasshopper

*M*. *packardii* Packard grasshopper

*M*. *fasciatus* -

*M*. *differentialis* differential grasshopper

*Hesperotittex* *viridis* snakeweed grasshopper

*Phoetaliotes* *nebrascensis* \*largeheaded grasshopper

Bandwinged grasshoppers (Oedipodinae):

*Encoptolophus* *costalis* dusky grasshopper

Slantfaced grasshoppers (Gomphocerinae)

*Amphitornus* *coloradus* striped grasshopper

\* denotes most common species found in study

***Insects Pests*** - The primary group of insect pests at Maxwell are
grasshoppers (see Table 1). Significant grasshopper outbreaks have
threatened both the economic viability of cooperative farmers and the
ability of the refuge farming program to meet objectives in providing
forage and habitat for migratory birds. Additionally, grasshoppers on
the refuge provide a reservoir of invading grasshoppers for neighboring
properties and can caused serious economic damage to crops and livestock
forage in neighboring lands.

The field study by Bomar, et al summarized in Table 1 is available in
the refuge files, and includes voluminous data on species composition of
grasshoppers encountered, levels of infection, and whether or not a
given species consumed bait.

**Refuge Management Objectives**

In following with the establishment of Maxwell National Wildlife Refuge
by the Migratory Bird Conservation Commission on August 24, 1965, and
given that the purpose for establishing the refuge was "for migratory
birds\...and other management purposes", the principal objectives of the
refuge are to:

-   provide a feeding and resting area for wintering migratory
    waterfowl.

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-   provide habitat for other migratory birds and non-migratory
    wildlife.

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-   allow for fish and wildlife oriented recreation.

Key to Maxwell meeting the establishing purpose and meeting these
principle objectives is the quality of habitat on the refuge.
Understanding that the native landscape where the refuge is situated was
short grass prairie, and that the native prairie has been fragmented and
significantly altered and disturbed through a history of agricultural
practices, is vital in developing a vision for the refuge pest
management program and habitat restoration efforts. The goal of this
Integrated Pest Management (IPM) Plan is not to just control pest
plants, but to develop strategies that will allow for and promote the
successful restoration of native short grass prairie habitat and
therefore optimize the quality of native grassland habitat on the
refuge. Restored, healthy prairie will not only provide quality habitat
towards meeting the refuge purpose and objectives, it will also resist
encroachment from invasive plants and other weeds.

In as much as the refuge farming program manages crops to provide
nutrition for migratory birds and other wildlife, the presence of
invasive plants and other weeds in crop fields reduces the ability of
the farming program to provide forage for the stated refuge purpose and
wildlife objectives. Controlling invasive plants and other weed pests in
crop fields will significantly aid the ability of the farming program in
successfully supporting the refuge purpose for migratory birds and aid
in meeting principal objectives.

To fulfill the goal for the IPM Program in promoting the refuge purpose
and aid in meeting refuge objectives, the following IPM Program goals
are identified:

-   increase the health and productivity of refuge crop fields by
    controlling or eliminating all invasive plant infestations in farm
    fields and reducing the population of other weed species.

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-   aid in the restoration of healthy short grass prairie habitats on
    the refuge by controlling or eliminating all invasive plant
    infestations on all of the abandoned farm fields that were
    cultivated but are no longer farmed, totaling about 500 acres. These
    sites will then be re-vegetated with native short grass prairie
    species, and the sites with the best soils, productivity and
    irrigation capability will be used to produce seed to re-vegetate
    other restoration sites. Migratory birds and other wildlife will
    benefit from the improved habitat quality, and overall biodiversity
    will be increased on these sites.

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-   aid in the restoration of healthy historic short grass prairie or
    other native habitat types by controlling or eliminating all
    invasive plant infestations on approximately 500 acres of disturbed
    range sites identified for restoration, thereby benefitting
    migratory birds and promoting the historic biodiversity of these
    sites.

Herbicide use will decrease over time as effective treatments bring pest
species under control and healthy habitats are restored. Refuge
management strategies to reach these goals for the management of pests
will be implemented on a priority basis, ranging from total elimination,
to control, suppression, and containment, as follows:

-   scout all areas of the refuge annually and identify, map, and
    monitor all infestations and treatment sites, applying standardized
    monitoring protocols.

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-   eliminate all newly discovered invasive plant infestations, and
    eliminate all infestations of **priority** invasive plants on and
    adjacent to farm fields, as rapidly as possible.

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-   control or eliminate invasive plants from all locations that present
    the best opportunities for infestations to spread, including
    roadsides, ditches, public use areas, work sites and stack yards;
    essentially anywhere vehicles and equipment could transport seeds or
    plant parts to new locations.

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-   control all existing infestations of **priority** and other invasive
    plants in non-crop range sites.

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-   control or suppress other agricultural weeds and insect pests in
    farm fields based on economic thresholds and seed bank reserves to
    reduce the future sprouting of seedlings.

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-   contain invasive plants around District dams and in District ditches
    serving as corridors for weed movement, in coordination with the
    Vermejo Conservancy District.

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-   apply** **the best weed science available, including biological
    controls, in developing and implementing the most effective
    individual strategy for controlling each pest species**.**

**History of Pest Management on the Refuge**

**Invasive Species -** Prior to 2000, there were no specific treatments
targeted at invasive species in either crop or non-crop sites, with only
two exceptions involving mowing and boom spraying musk with Canada
thistles. Otherwise, musk, bull and Canada thistles, Russian knapweed
and hoary cress were disced along with other weeds in agricultural
fields, some of which were planted to corn and treated with 2,4-D
post-emergence. These types of general treatments with discing and
limited spray applications were ineffective, and the discing undoubtedly
spread species with perennial root systems such as Canada thistle,
Russian knapweed and hoary cress. Please note that the use of trade
names in this document is for documentation purposes only and such
references do not imply endorsement of any particular product over
another by the author or the U.S. Fish & Wildlife Service.

As for the exceptions, a small scale and ineffective effort was
initiated to treat combined infestations of Canada and musk thistles in
two fields across from and north of headquarters in 1998 and 1999. In
1998 these two sites were mowed with an agricultural mower (i.e., a
\"bush hog\") in June as the musk thistles began to bloom in earnest,
then sprayed over-the-top with 8 ounces/acre Weedar 64 (46.8 % active
ingredient 2,4-D) in August, using an agricultural boom sprayer. In
1999, the infested areas were similarly mowed in June and sprayed with
16 ounces/acre Weedar 64 in September. However, the Weedar 64 label
specifies applying as much as eight times those rates in treating Canada
thistle, which is co-located with the musk thistles being treated. The
treatments failed to control Canada thistle vegetative growth or root
systems. In the case of musk thistle, the timing of herbicide
application was "post-bloom," so that the mowed musk thistle plants,
assuming they had not already set seeds before mowing, were given the
opportunity to regrow to a low height, flower, and go to seed rapidly
after being stressed by mowing. The boom spraying could have been
effective on musk thistle if the application had been two to three weeks
after mowing, before the musk thistles regrew blooms and set seed.
Because the timing and concentration of spray applications permitted
musk thistle seed production and were too weak to suppress Canada
thistle, the 1998 and 1999 control efforts were ineffective. The general
2,4-D treatments in fields also were ineffective in controlling Russian
knapweed, hoary cress, and field bindweed when treated along with other
agricultural weeds in corn fields.

In summary, prior to 2000, invasive species were generally not targeted
for treatment, and the two range sites (actually abandoned crop fields)
that were treated received ineffective treatments. Invasive species were
not well understood as to their identity, biology or distribution.**
**Also, prior to 2000, Maxwell NWR did not have the use of a
four-wheeler cycle to provide low-impact, off-road access for field
scouting, mapping, hand spraying, or follow up monitoring, limiting the
amount of off-road area that could be scouted and managed.

In 2000, the refuge began using a four-wheeler to scout virtually all
portions of the refuge to detect invasive weed species, including farm
fields, range sites, right-of-ways, and around dams and ditches. The
four-wheeler and scouting effort dramatically increased capabilities and
success in locating, identifying, mapping, and treating infestations.
Attempts were made to custom treat all infestations discovered in 2000,
to the greatest extent possible, with the following treatments and
combination of treatments applied:

-   two **hoary cress** patches were detected and hand sprayed at two
    different rates with a tank mix of Escort (methsulfuron methyl) and
    Weedar 64 (amine formulation of 2, 4-D), but applications were later
    than ideal following the plants discovery, as the plants were
    already in bloom. While the plants seemed to be suppressed following
    spraying in 2000, neither rate seemed to decrease the regrowth and
    bloom of either treated patch in 2001. In 2001, these two sites and
    all additional discovered patches were treated with the higher rate
    of the Escort and Weedar tank mix at early bud, but the
    effectiveness of these treatments will not be seen until spring
    of 2002. Also in 2001, one newly discovered patch of hoary cress,
    growing among a larger patch of Russian knapweed located southeast
    of Dam 12, was sprayed with the same tank mix used for knapweed (see
    below). Note that with other species, the key to discovering hoary
    cress infestation was scouting during the bloom.

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-   thousands of **musk and bull thistle** plants were individually spot
    treated by hand with Weedar 64 in 2000, and, if plants were
    discovered after blooms had been set, a tank mix of Weedar 64 and
    Telar DF (chlorsulfuron) was spot applied to each of many hundreds
    of plants to arrest seed production. Larger patches in advanced
    flower stage (but before seed set) were mowed and then boom sprayed
    with Weedar 64, a combination mechanical-herbicide treatment that
    proved extremely effective at killing both the second year plants
    trying to go to seed and the first year seedlings that had just
    sprouted. A special effort was made to remove all musk thistles in
    crop fields. Hand hoeing hundreds of rosettes proved ineffective as
    the cut plant would eventually respond from the taproot and bloom.
    Spraying started earlier in 2001, with thousands of rosettes spot
    treated by hand with 2, 4-D. **Common mullein** was also sprayed
    opportunistically with 2, 4-D in 2000 and 2001, with excellent kill
    and control when treated before flowering. Both musk and bull
    thistle were easy to control with 2, 4-D if plants were treated
    before they went to the bud stage, but locating all the rosettes in
    an area proved to be impossible, requiring a treatment regime that
    included revisiting treated sites to touch up plants that were
    missed on the first visit. There also seemed to be a delayed
    chronology with at least a few "late bloomers", so an effective
    treatment strategy requires more than one visit to an infested site
    some weeks apart.

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-   scouting during the "June bloom" indicated that **Canada thistle
    **was very well established and widely spread. It also proved
    difficult to control. Some Canada thistle patches were
    opportunistically hand treated either with 2, 4-D while spraying
    musk thistle (i.e., with Weedar 64, which proved ineffective) or
    with the 2, 4-D/clopyralid/picloram mix (i.e., with the Weedar
    64/Reclaim/Tordon 22K mix, which was extremely effective) in the
    course of treating co-located Russian knapweed. Where smaller
    patches prevailed, a tank mix of 2, 4-D and Reclaim (clopyralid) was
    hand applied, including spot applications in alfalfa fields. The
    thistles treated in irrigated alfalfa fields regrew and were
    retreated two additional times in 2000. Where larger patches
    dominated the landscape the boom sprayer was used to apply the same
    tank mix of 2, 4-D and clopyralid. While these tank mixes achieved
    top kill, they gave variable results in the way of lasting control
    of regrowth later in 2000 and in 2001. Results ranged from apparent
    control to mixed control with limited suppression. One area heavily
    infested with both musk and Canada thistle was mowed and boom
    sprayed with 2, 4-D and Telar DF (chlorsulfuron) as the musk
    thistles were trying to regrow and go to bloom, with good results.
    In 2001, new strategies were employed to stress Canada thistle
    before herbicide treatment, either through discing in fields or
    mowing in range sites. Applications included treatments with the new
    WetBlade mower-applicator, after the area had been mechanically
    mowed, but it is too early to evaluate results.

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-   field scouting in 2000 discovered **Russian knapweed** for the first
    time on the refuge in several different habitat situations. G field
    was planted to corn before scouting determined that the field had a
    tremendous weed load including Canada thistle and Russian knapweed.
    Boom spraying the corn field with 2, 4-D post-emergence had
    virtually no effect on the knapweed, and hand applications with 2,
    4-D and Reclaim (clopyralid) to individual plants stunted the
    knapweed's growth, but did not kill the plants. Other non-crop
    knapweed infestations were hand treated with a tank mix recommended
    by Whitson (in Sheley and Tetroff,1999) including (by active
    ingredient) 1 part clopyralid to 2 parts picloram to 4 parts 2, 4-D.
    This 1:2:4 mix was extremely effective on Russian knapweed when
    treatments were applied "spray to wet" at the early bud stage, using
    dye as an indicator. In fact, the infestations treated with this
    1:2:4 "geometric mix" showed no regrowth in 2001 except on the edges
    of the stand where the application was likely not uniform. The scant
    regrowth in 2001 was touched up with the same geometric mix, and are
    expected to be eradicated within two or three spraying cycles. Note
    that no regrowth occurred until the next growing season. In general,
    any application that did not include Tordon 22K was ineffective on
    knapweed. Continued monitoring will determine the need for
    additional treatments.

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-   prior to 2000 **salt cedar** was not treated, but was only present
    as several scattered, individual plants. These individuals were
    sprayed with a foliar treatment of triclopyr (Garlon 3A), but the
    larger plants showed some regrowth in 2001. These were chainsawed
    and stump treated with 50% Garlon. However, just when we thought
    salt cedar had been eradicated on Maxwell, a disturbing discovery
    was made over the summer of 2001. Tens of thousands of young sprouts
    appeared above the water line around the drawn-down shoreline of
    Lakes 12 and 13, likely the product of seeds washed in from
    Stubblefield Reservoir in the May, 1999 flood. Thousands of these
    young seedlings at Lake 12 were hand sprayed with Garlon 3A on
    September 13^th^ of 2001.

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-   a few **Russian elm** trees had been effectively sprayed
    over-the-top with foliar applications of Weedar 64 prior to 2000. In
    2000 and 2001, stands of seedlings spreading out from larger trees
    were mowed with a bush hog. Some areas with larger trees, such as
    across from headquarters, were cut with a chainsaw and stump cut
    treated with 50% Garlon 3A The handful of **Russian olive** trees
    that were planted around headquarters met a similar fate in 2000 and
    2001, as they were cut with a chainsaw and the stumps were painted
    with 50% Garlon 3A. Resprouting was touched up with a Garlon 3A
    treatment.

As control strategies progressed up the learning curve in 2001,
treatments on Canada thistle were expanded to include the use of a
WetBlade rotary mower, combining mechanical and herbicide controls in a
single treatment. Sites were prepared by mowing in late winter with a
regular rotary mower (i.e., bush hog). This pretreatment provided
multiple benefits, including the removal of dense growth from previous
years, improving the efficiency of the WetBlade, and increasing
visibility of the target pest plants, including underlying musk thistle,
Russian knapweed and hoary cress infestations. Early pre-mowing also
made the area less attractive to ground-nesting birds, minimizing the
likelihood of impacting a nest or young when using the WetBlade later in
the spring. Pre-mowing with a sturdy bush hog also allowed for the
discovery and removal of various hazards that could damage the more
fragile (and more expensive) WetBlade mower. Several mechanical problems
were encountered in using the WetBlade in 2001, so the "jury is still
out" on how useful and reliable the device will be and how effective the
treatments were. However, the WetBlade mower applies only a small amount
of herbicide to the area being cut (on the order of 1/5th to 1/10th the
volume of boom spraying) and there is virtually no drift produced, a
great advantage in the windy New Mexico highlands. As with any new tool,
time and experience will show us the best management applications for
this device.

Another new herbicide used on Canada thistle in 2001 was Roundup Ultra
(glyphosate). Applications planned for 2001 included boom spraying in
selected crop fields that were summer-fallowed and with the wetblade in
range sites, but the results of the effects on the root system will not
be apparent until the 2002 growing season demonstrates how much regrowth
comes back from the root system.

**[Grasshoppers]{.underline}**

Two insecticides have traditionally been used for grasshopper control
over the years at Maxwell Refuge, Malathion and carbaryl (Sevin XLR).
These products have been used to fend off larger grasshopper
infestations, with use changing from Malathion to carbaryl in more
recent years.

Bomar, et al (1990), summarized the species composition of grasshoppers
encountered, their levels of infection, whether or not a given species
was consuming *Nosema locustae* bait, and whether the bait was
effective. Results of the study indicated that the *Nosema* product,
Nolobait, was most effective at infesting and controlling spurthroated
grasshoppers, while the slantfaced species was unaffected as they did
not consume the wheat bran-based product.

The study also showed that insectivorous birds were more common in
treated sites, suggesting that the birds advantageously moved into
treated areas to feed on sick, more easily caught grasshoppers (also
likely in insecticide-treated sites). The parasitic wasp *Scelio*
*opacus* was also found in the study, and may warrant additional
consideration as a possible control agent, if a supply source can be
found.

Results from this study will be used in assessing whether future
infestations are attracted to treatment. However, results will not be
used to predict effectiveness, since initial efforts may have been
influenced by poor storage conditions and/or application of the product
when grasshoppers were in the wrong instar stage.

**Management Alternatives**

**No Action**: Employing a "no action" alternative would allow invasive
exotic plant infestations (including most conspicuously musk, bull and
Canada thistles, Russian knapweed, hoary cress, salt cedar and Siberian
elm) to continue spreading, invading additional refuge habitats,
including fields, pastures, roadsides, and dams and irrigation ditches
on and around the refuge. Taking no action would allow grasshopper
infestations to decimate refuge crops and grasslands, including newly
restored grasslands. This option would have significant negative impacts
to the ecosystem, potentially crippling the refuge\'s ability to meet
habitat objectives for migratory birds. The infestations would
predictably spread to neighboring landowners\' rangeland and pastures,
reducing forage and yields and creating larger infestations, causing
increasing economic impacts. "No action" would further increase
anti-government sentiment. Additionally, Maxwell Refuge is an integral
part of the interagency work group within Colfax County focusing on the
control of invasive plants. Considering the purpose and objectives for
the refuge and the presence of several noxious weeds classified by New
Mexico as Class A or B noxious weeds, the "no action" alternative is
unacceptable.

Options for management of pest species fall into two categories:
controlling pest plant species, and controlling grasshopper species.
Options for controlling pest plants include the application of
mechanical treatments (mowing, discing, and hand pulling or hoeing),
biological controls, grazing, prescribed fire, herbicide applications,
and cultural controls. Also considered is the "wet blade" mower which
combines mechanical mowing with a herbicide application in a single
treatment. Options for controlling grasshoppers include biological
controls, applying pesticides, and cultural controls including a
planning process for planting crops that minimizes the opportunity for
insect damage.

This IPM Plan for Maxwell National Wildlife Refuge draws from a
combination of these options in what may be called a "**Preferred
Alternative**" which assimilates all of the best management practices
and weed science for controlling pest species.

**Options for Pest Control:** There are a variety of treatment options
to consider in managing weeds and invasive plant and grasshopper
infestations at Maxwell. The primary options for control are biological,
cultural, mechanical and chemical (herbicide and insecticide).
Prevention, as in preventing the spread of existing infestations and
potential re-invasion, is also an important consideration in developing
a successful integrated strategy for managing pest populations. The
ultimate control action against invasive plant species on Maxwell's
disturbed rangeland will be to reestablish healthy native short-grass
prairie plant communities. Therefore, the rehabilitation of abandoned
crop fields and altered range sites is in itself an important aspect of
the preferred alternative. The specific control option, or combination
of control options, is discussed for each pest species in the section
IPM Methods fro Priority Species beginning on page 27.

**Pest Management Elements: **Because the "no action" alternative is
unacceptable, priority pests will be managed on Maxwell NWR. Management
will include three important components: scouting and mapping,
treatment, and follow up monitoring.

*Scouting and Mapping *- A four-wheeler will be used to scout all areas
of the refuge annually. All infestations will be mapped using a global
positioning system (GPS) unit to acquire both the location (in Universal
Transverse Mercator \[UTM\] units using NAD83) and dimensions of the
infestations to estimate the size of the area. Mapping will follow
standardized protocols for the values used for "acres infested", ranging
from 0.1 acres for small infestations (including single plants), to
0.1-0.5 acres, 1.0-5.0 acres, 5.0-10.0 acres, etc. Appropriate software
will be employed (ArcView, TopoZone.com, etc.) so that the location of
the computer's mouse cursor will correspond with a numeric value for
that precise location displayed in UTMs, since this system enables more
ready digitized mapping than traditional latitude/longitude and enables
a user to "work backward" using the cursor to locate a point with a
specific UTM value.

*Treatment*- Selected treatments will be comprehensive, including use of
herbicide and non-herbicide methods, where possible. Mowing will be used
in a number of ways, as described under selected management strategies
for each species (see below). Part of the purpose of Maxwell as a
National Wildlife Refuge "for migratory birds" is to provide nesting
opportunities for those birds. Locally nesting species include not only
ducks, but "grassland obligate" species such as the grasshopper sparrow
and western meadowlark. These ground nesting species require overlying
vegetation to nest successfully, and management needs to be mindful of
their nesting requirements. Not more than 5% of the refuge will be mowed
or burned in any one year to limit the removal of vegetation in those
areas, and these treatments will not be applied during the nesting
season unless the area was pre-mowed in late winter to remove dense
cover.

Only herbicides expected to be effective have been selected as
treatments in this plan, and among these, those that are lowest in
environmental risk, considering specific resources at the site, are
identified. Table 3 summarizes expected efficacy of selected herbicides
that are relatively low in risk, based on "Weed Control Manual 2002
Recommendations," previous refuge experience, and other guidance. Weeds
listed in this table include priority invasive species, as well as
yellow starthistle and leafy spurge. The latter species are included
because of their highly invasive character and their likelihood to
colonize the Refuge in the very near future. Herbicides selected for
potential use on the refuge are double-boxed.

Certain herbicides, prone to volatilization and/or runoff, and/or with
potential adverse effects to non-target vegetation or wildlife, were
excluded from consideration as alternatives even though they are
effective against some of the above weed pests. Excluded herbicides
included Atrazine (prone to both volatilization and runoff with likely
subsequent contamination of groundwater and

surface waters and toxicity to invertebrates, amphibians, and fish);
2,4-D ester formulations (more toxic than amine formulations to
invertebrates and fish and more prone to volatilization and damage of
nontarget plants and crops than amine formulations; MCPA (very
persistent in some soils and waters and moderately to highly toxic to
mammals and birds); oxyfluorfen (highly to extremely toxic to fish;
moderately to highly toxic to invertebrates); and quinclorac (highly
volatile with possible damage to adjacent broadleaf crops and native
species \[especially those in the Solenaceae\] and also moderately toxic
to mammals). Some formulations of quinclorac are also inhalation hazard
to birds and mammals.

Additional information about each selected herbicide, as well as general
safety and efficacy considerations, and the basis of the selection, are
provided below. This list is not comprehensive as to potential tank
mixes, but does address tank mixes that will be tried in 2002.

**TABLE 3. OBSERVED EFFICACY OF HERBICIDES AT MAXWELL NWR**.

"I" indicates ineffective, "S" indicates suppression, "C" indicates
apparent control, and "E" indicates extremely effective. "Y" indicates
yet to be determined and "V" indicates variable success and may indicate
suboptimal application conditions or growth stage, or the development of
some resistant genomes. A "-" indicates no treatment.

+-------+-------+-------+-------+-------+-------+-------+-------+
| Herb  | C     | Musk/ | Field | Hoary | Ru    | Salt  | Ru    |
| icide | anada |       |       |       | ssian | Cedar | ssian |
|       |       | Bull  | Bin   | Cress |       |       | Elm   |
|       | Th    |       | dweed |       | Kna   |       |       |
|       | istle | Th    |       |       | pweed |       |       |
|       |       | istle |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| 2,4-D | I     | C     | S     | I     | I     | I     | S / C |
| Amine |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| Met   | \-    | \-    | \-    | I     | \-    | \-    | \-    |
| sulfu |       |       |       |       |       |       |       |
| ron-M |       |       |       |       |       |       |       |
| ethyl |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| 2     | V     | C     | \-    | \-    | I     | \-    | \-    |
| ,4-D/ |       |       |       |       |       |       |       |
|       |       |       |       |       |       |       |       |
| Clopy |       |       |       |       |       |       |       |
| ralid |       |       |       |       |       |       |       |
| Tank  |       |       |       |       |       |       |       |
| Mix   |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| 2     | E     | \-    | \-    | \-    | E     | \-    | \-    |
| ,4-D/ |       |       |       |       |       |       |       |
|       |       |       |       |       |       |       |       |
| C     |       |       |       |       |       |       |       |
| lopyr |       |       |       |       |       |       |       |
| alid/ |       |       |       |       |       |       |       |
|       |       |       |       |       |       |       |       |
| Pic   |       |       |       |       |       |       |       |
| loram |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| Glyph | S     | \-    | \-    | \-    | \-    | S     | S     |
| osate |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| 2     | C     | C     | \-    | \-    | \-    | \-    | \-    |
| ,4-D/ |       |       |       |       |       |       |       |
| Ch    |       |       |       |       |       |       |       |
| lorsu |       |       |       |       |       |       |       |
| lfuro |       |       |       |       |       |       |       |
| n^\ ^ |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
| 2     | \-    | \-    | \-    | \-    | \-    | C     | C     |
| ,4-D/ |       |       |       |       |       |       |       |
| Tric  |       |       |       |       |       |       |       |
| lopyr |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+
|       |       |       |       |       |       |       |       |
+-------+-------+-------+-------+-------+-------+-------+-------+

Table 3 Notes: tank mixes generally failed to control hoary cress. This
could be due to the different formulations of metsulfuron-methyl (Ally
or Escort) and on whether the existing site was formerly fallow or
pasture and rangeland. Beck et al. (1990) reported good musk thistle
control with metsulfuron or chlorsulfuron at 221 g a.i./hectare during
bolting, but the refuge had excellent results with just 2, 4-D at an
early growth stage. The manual shows that picloram controls thistles and
knapweeds, without identifying specific species. The efficacy of the 2,
4-D, picloram and clopyralid tank mix is based on refuge experience in
controlling Russian knapweed and two isolated colonies of Canada thistle
were also fully, or nearly fully controlled. ^\ ^Chlorsulfuron and
Imazapyr are not listed for pasture or rangeland use, but are labeled
for noncrop sites. Excellent control of two years of musk thistle growth
occurred on the refuge by mowing followed by either a 2, 4-D or a
2,4-D/chlorsulfuron mix.

*Best Management Practices during Herbicide Treatments. *All
applications will be planned and conducted with the coordination and
under the supervision of a licensed applicator certified in the
appropriate state category which covers the application. Boom spraying
will only be conducted when wind speeds average** **7 miles per hour
(mph) or less, and preferably in the 3 to 5 mph range, with no gusts
greater than 10 mph. Anti-drift nozzles will be utilized. Inversion
conditions, typical in calm and very low wind conditions, will be
avoided since these conditions facilitate large-scale herbicide drift
off site. Only enclosed cab equipment with air conditioning will be used
to boom spray, offering the maximum protection from contamination to the
operator/applicator.

However, a standard enclosed cab tractor does not meet the PPE standard
when applying products that require a respirator for the applicator. Due
to frequent windy conditions during afternoon periods and early spring
in general, boom spraying will typically be conducted in the early
morning in late spring or summer, based on observations and the weather
forecast. Spray applications will not be conducted on days when there is
a 30% or higher forecast for rain within 6 hours, except for products
that are rapidly rainfast (e.g., glyphosate in 1 hour). Applications of
herbicides and insecticides prone to leaching will also not be made
within 24 -48 hours of likely (greater than 50% chance of) moderate to
heavy rainfall. Certain herbicides are less likely to leach and more
effective following a light rainfall that moistens the soil, and these
conditions are usually indicated as optimal on the label. Refuge
herbicide applications will take these factors into consideration, and
when feasible, will take advantage of these factors.

A hand held wind meter will be used to determine wind speed at the
application site, and wind direction will also be evaluated relative to
any sensitive sites. If the wind temporarily picks up during boom
spraying, drift can be reduced by lowering the nozzle pressure, thereby
reducing droplet size. However, this practice will reduce the
application rate for the area affected, and would have to be combined
with shifting to a lower gear (reduced speed) to approximate the same
standardized application rate. When boom spraying, it is desirable to
maintain the same combination of gear and rpm's used in calibrating the
boom sprayer, so any exceptions to this standard practice will be
minimized.** **Also, the refuge will routinely limit herbicide drift by
using anti-drift nozzles with openings of not greater than 1/16 inch and
boom pressures of no more than 30 psi, with 20 psi adjacent to sensitive
sites not in the treatment area. A nontoxic anti-drift agent will also
be used when allowed by the label, especially adjacent to sensitive
sites.

To aid staff involved in mixing, a conversion table will be developed
and posted in the mixing area stating the amount of product needed for
any given percentage of tank mix for each size of tank used on the
refuge. In the case of Maxwell , there are 14, 50 and 200 gallon
herbicide tanks, so the table would state the amount of product needed
to make up each percentage mix based on that tank size. Also, each tank
will be clearly labeled "Pesticides Only", or in a similar warning.

*Personal Protective Equipment.* Applicators will wear personal
protective equipment (PPE) in accordance** **with the specific labeling
requirements for each product, and all PPE will be supplied by the
station, as needed. The required PPE, as specified by the label, will be
worn at all times during handling, mixing and application. Fresh clean
clothing, such as coveralls, laundered after each use, will be put on
daily before handling pesticides used in application and removed before
engaging in other duties unrelated to the application. Mixers and
applicators will wear a pair of footwear specially designated for
herbicide use, and will not wear the designated footwear for other
operations to minimize contamination.

As exposure to concentrated product is usually greatest at mixing, extra
care will be taken during the mixing period. Persons involved in mixing
will be best protected if they wear extra long gloves, an apron,
designated footwear and face shield throughout the mixing process, in
addition to the protective clothing required by the label. Coveralls and
other clothing used in an application will be laundered separately from
other laundry items, or disposable Tyvek clothing may be used.
Transportation, storage, handling, mixing and disposal of pesticide
containers will be consistent with label requirements, EPA and OSHA
requirements, and Service policy. Anyone handling, mixing or applying
herbicides will have a background medical examination including blood
work to establish baseline data, and final blood work should also be
done when anyone leaves their position.

Currently, there are no products requiring the use of a respirator
proposed in this plan. Should changes occur, any respirator use by
Service personnel will take place following establishment of a written
Respirator Program, fit testing, physical examination (including
pulmonary function and blood work for contaminants), and proper storage
of the respirator. Alternatively, the refuge may contract with a
commercial certified pesticide applicator in the area for some
applications.

*Surfactants and anti-drift agents. *Surfactants provide benefits by
increasing plant uptake of the applied herbicide and will normally be
used if specified on the label. To the maximum extent possible,
consistent with label specifications, the refuge will select surfactants
and anti-drift agents that are themselves low in toxicity by comparing
information available from the product MSDS's and by consulting
contaminant specialists when additional information is needed.

*Dyes.* A non-toxic dye may be used to assist applicators in visually
determining target acquisition, potential drift or over-spray, the
amount of treatment applied, and to aid in discovering equipment leaks.
If a leak is discovered, the application will be stopped until repairs
can be made. Any dyes used must also be non-toxic.

*Spills*. If a spill occurs, the top priority will be the
decontamination of any personnel involved. Any gloves, clothing or other
PPE involved in the contamination will be removed as soon as practical
and cleaned or discarded appropriately, and the applicator will be
provided with the time and opportunity to wash up and decontaminate as
thoroughly as needed. A continuous emergency eye wash station will be
available near the mixing station. Whenever possible, mixing stations
will be located near a shower stall or other means of thoroughly washing
off and decontaminating the entire body. A "spill kit" with absorbent
material will be kept on hand wherever pesticides are stored, mixed, or
when transported, and the storage and mixing areas will provide
containment appropriate for the volume of material involved. A tarp will
be used to cover any spill site until retrieval of the spilled material,
cleanup or capping of the site occurs. If the spill can not be cleaned
up and contained immediately, State spill response personnel will be
contacted.

*Labels and Material Safety Data Sheets*. Prior to each treatment season
and prior to mixing or applying any product for the first time each
season, all applicators will review the label, MSDS, and Pesticide Use
Proposal (PUP) for each product, determining the target pest,
appropriate mix rate(s), PPE, and other variables listed on the label.
Labels and MSDS's will be maintained both in the shop and as separate,
laminated copies in the mixing area. A written reference for each tank
to be mixed (on a note pad, chalk board, dry erase board, etc.) will be
provided in the mixing area to use as a quick reference while mixing is
in progress.

*Notification. *Staff, volunteers, and members of the public who could
be in or near the treatment area within the stated reentry time period
on the label will be alerted concerning treatment areas, and posting
will occur in any site where the individuals might inadvertently become
exposed to a pesticide during other activities on the refuge. Where
required by the label, sites will also be posted on all corners and at
other locations of likely site entry, such as trailheads. The Refuge
will also notify any adjacent property owners of an intended
application, if private individuals have requested notification. Special
efforts will be made to contact neighbors that are beekeepers or who
have indicated that they have special chemical sensitivities.

*Pesticide Disposal*. Empty product containers will be triple rinsed and
the rinsate will be dumped into an appropriate tank mix for an
application treatment. Empty containers will be triple rinsed and
disposed of properly and a file record will be obtained and filed to
document proper disposal. Solutions used to clean equipment after
application such as water, or a water and ammonia mix, will be
recaptured and reused or applied to a pest plant infestation, which
happen to be conveniently located near the mixing area.

*Training and Supervision of Pesticide Applicators.* At least one staff
member will be certified by the State of New Mexico as a "Public Lands
Applicator", and any staff member applying a herbicide or insecticide
must be operating under his/her **direct** supervision. Preferably, all
staff involved in the station pest management program will be afforded
the opportunity to attend appropriate training. New staff unfamiliar
with the station procedures for storage, mixing, handling, applying and
disposing of pesticides and containers, will receive orientation and
training **before** handling or using any products, and documentation of
that training, and related training, will be placed in the refuge files
for documentation.

*Log of Pesticide Use. *A log will be maintained to record and document
each application, applicator, amount of product(s) used, location, time
of day, acreage and, for boom spaying treatments, wind speed. These
records will assist in producing the annual Pesticide Use Report and
will meet other documentation requirements.

SELECTED HERBICIDES

[Glyphosate]{.underline} (Rodeo or Roundup, or similar products).
Glyphosate is a systemic herbicide with little soil residual activity.
Because glyphosate tends to suppress rather than control thistles and
because it adversely affects both broadleaves and grasses, it will be
mainly used be as a preplant or fallow treatment, or as a spot, wick, or
wipe treatment to target plants amid desired species. Also, this
herbicide will be used immediately adjacent to wetlands and water
bodies.** **Trials in other locations show that glyphosate can provide
excellent thistle control, but that control is reduced when glyphosate
is tank-mixed with 2,4-D, so this practice will be avoided when the
target is thistles.

On an acute toxicity basis (48-114 hour exposures, depending on species)
, glyphosate ranks as slightly to moderately toxic to mammals and birds
and slightly toxic to practically nontoxic to fish and aquatic
invertebrates. At labeled doses, toxicity to wildlife is expected to be
negligible. The surfactant in Roundup is somewhat more toxic to fish,
amphibians, and invertebrates than glyphosate itself. Thus, Rodeo, a
glyphosate product that lacks this surfactant, is labeled for wetland
and aquatic sites rather than Roundup. The refuge will use Rodeo
together with a nontoxic surfactants, such as LI700, in sites
immediately adjacent to aquatic sites or in sites with invertebrate
species of concern.

One attribute of glyphosate is that it sorbs well to soil and sediment
with little continued herbicidal activity, making this herbicide less
likely to leach or affect adjacent nontarget plants. Roundup at 1
qt/acre (or Rodeo in wetland and riparian sites) has been a very
effective post-harvest treatment for Canada thistle in many locations,
but was not used on thistles at Maxwell NWR. Several adjustments in
previous practices may increase efficacy, including timing changes,
changes in water source, and addition of ammonium sulfate to the tank
mix. Efficacy can be increased if there is no tillage occur for 14 days
after application and there are at least 21 frost-free days after
application. A possible problem with poor herbicide performance is that
glyphosate tends to be most effective when diluted with low hardness,
circumneutral, clean (sediment-free) water. Also, studies show that
glyphosate tends to be most effective on Canada thistles when
groundwater is close to the surface. Water high in solids or hardness
\[high alkalinity waters\], can greatly diminish effectiveness. Sources
of surface water on Maxwell NWR, including irrigation drainwater, are
high in alkalinity, hardness and suspended sediments, potentially
reducing glyphosate efficacy. Many of the refuge's Canada thistles are
also located in dry soils not close to groundwater, also limiting
efficacy in such sites. Also, in sites not immediately adjacent to water
or wetlands, efficacy will be enhanced by adding ammonium sulfate.** **

[Clopyralid]{.underline} (Transline, Reclaim or Stinger). Clopyralid
alone is listed as controlling Canada and bull thistle, but not musk
thistle (but an inexpensive application of 2, 4-D amine works fine on
musk and bull thistles, anyway). A maximum rate of 1.33 pt/acre
clopyralid will be used, with lower rates in tank mixes with other
herbicides.

On an acute toxicity basis, clopyralid ranks as practically nontoxic to
aquatic species and slightly to practically nontoxic to mammals and
birds. Stands of perennial broadleaves usually improve after spraying if
rainfall is adequate. Although these attributes are desirable, this
compound remains highly phytotoxic to certain broadleaves (especially
legumes) at very low concentrations and can affect native forbs in
grasslands or adjacent broadleaf crops. Label restrictions do not allow
its use when it can enter irrigation drain water due to potential
downstream crop damage. The compound can be transported by wind on
blowing dust or in the urine of large mammals, affecting nontarget
vegetation. Therefore, limitations will be observed on its use in
farmlands, near ditches, or near irrigation waters and reservoir berms
(even the outside of berms). In the past, there has been excellent
Canada thistle control in some refuge locations with clopyralid alone.
In other locations, treatments were less successful, possibly due to the
development of resistant Canada thistle genomes \[Canada thistle
resistance to clopyralid has been recorded in many U.S. locations\].
Since the Refuge's experience has been variable and since this herbicide
alone may not control musk thistle, a combination of herbicides or
alternation of herbicides will be considered rather than long-term use
of clopyralid alone, especially when musk thistle are present.

[2,4-D.]{.underline} Rates of use will depend on the particular
formulation selected, and species to be treated, but will generally be
between 0.66 - 4 pt/acre, if used alone. The amine formulation of 2,4-D
(e.g., Weedar 64) ranks as only slightly toxic to practically nontoxic
to aquatic species and practically nontoxic to birds and mammals.
Although this form is prone to leaching, it is less toxic to aquatic
species and less likely than other(ester) 2,4-D formulations to
volatilize and affect adjacent nontarget plants or crops through
atmospheric transport. No threat will exist to drinking water
contamination since there are no drinking water uses on the refuge.
Also, 2,4-D amine has a short half-life in water, normally 1-3 weeks and
is unlikely to persist. As discussed above, this herbicide alone was
previously found to be ineffective on Canada thistle, but it may
contribute to the effectiveness in tank mixes discussed below. Also, its
effectiveness may improve if used when thistles are young and growing in
the spring or fall rather than during the summer. Desired legumes are
especially affected by 2,4-D, so precautions need to be taken near
desired native legumes or crops such as alfalfa. Both musk and bull
thistles, as well as multiple agricultural weeds such as cocklebur and
common ragweed are effectively controlled by 2,4-D treatments.

[2,4-D/Clopyralid Mixture]{.underline} (Curtail). This mixture has
proved promising results on the refuge to date to control Canada and
musk thistle, although a follow up treatment is sometimes necessary. It
is also labeled for controlling Russian knapweed and yellow starthistle.
It may control bull thistle, but is not listed as controlling bull
thistle on the label (here again, 2,4-D works fine). The combination of
the two pesticides is less likely to result in herbicide resistance in
the thistles. Normally 2-4 qt/acre of the premix is applied. This
combination is a control option for Canada thistle co-located with
infestations of musk and bull thistle (but gave variable results on
Canada thistle), and is also listed as suppressing Russian knapweed (but
was quite ineffective on Russian knapweed on the refuge in G Field in
2000).

Because of the phytotoxicity of clopyralid, uses of this mix will need
to be based on label restrictions discussed above and on protecting
desired refuge broadleaves. Reseeding with any broadleaves in fallowed
crop sites will only occur after bioassays or field observations of
seedling growth indicate it is safe.

[Picloram, 2,4-D, and Clopyralid Mixture]{.underline}. After Sheley and
Petroff (1999). Picloram alone (Tordon 22K) is labeled for controlling
broadleaf weeds in permanent pastures and grasslands west of the
Mississippi River, with tank mixes recommended for treating selected
plants, including Russian knapweed. This mix was the primary agent used
on Russian knapweed, and proved to be very effective. It is also labeled
for use in fallowed lands. It is not labeled for controlling Canada
thistle in grassland, but is labeled for controlling this thistle in
fallow land and as a post-harvest or fallow treatment in grains.
Treatment is recommended prior to bud stage. Land must be fallowed for
several years before replanting to broadleaves or broadleaf crops. This
tank mix was nearly 100% effective on isolated Canada thistle patches
near Russian knapweed control sites in 2001.

Picloram is a **restricted use** herbicide requiring greater safety
precautions than most other herbicides proposed. There are also label
restrictions on its use in croplands, since picloram remains phytotoxic
to many plant species, including crop species, and has a half-life of
4-73 weeks, depending on soil microorganisms present. On an acute
toxicity basis, picloram ranks as practically nontoxic to moderately
toxic to mammals, practically nontoxic to birds, slightly to moderately
toxic to aquatic species, and nontoxic to bees.** **The most sensitive
fish tested include certain salmonids and catfish, and the later are
stocked in Lake 13.

Along with its potential to be moderately toxic to certain aquatic
species, picloram is highly soluble and leachable, with a long half-life
possible in turbid or deep water. It has the capacity to accumulate in
aquatic systems, if used repeatedly. Thus, this chemical is mostly
suitable for upland non-farm sites with low-permeability soils (silts,
clays or silty loams) where groundwater is not close to the surface or
where there is an intervening low- permeability soil layer such as clay
or caliche above groundwater aquifers. Wick, wipe, or WetBlade
(trademark of Birch Company) treatments to foliage or stems may occur in
other sun-exposed locations, since the compound does break down readily
in light. ** **There are specific use directions for use of picloram in
New Mexico that the refuge will follow, found in the supplemental label
for the State. Maxwell NWR will strictly follow label limitations,
applying this mix no more than once per year per site, and avoiding use
near surface waters or drainages to minimize environmental impacts. At
labeled rates, impacts to birds and mammals are unlikely.

[Metsulfuron Methyl]{.underline} (Ally, Oust, or Escort). This
sulfonylurea herbicide ranks as slightly to moderately toxic to mammals;
practically nontoxic to birds, fish, and invertebrates; and nontoxic to
bees if exposures are short term. Known as an ALS inhibitor, it works by
interfering with certain amino acid synthesis and may be highly
effective if resistant biotypes have not yet developed. Like clopyralid,
metsulfuron methyl is mobile in water and dust and remains phytotoxic to
some broadleaf plant species at extremely low concentrations.

Metsulfuron methyl is especially leachable and persistent in alkaline
sites, and thus should not be used in the refuge's alkaline flats or
playas. Ally and Oust are listed as suppressing, but not controlling
Canada thistle, and are not listed as either controlling or suppressing
musk or bull thistle in rangeland, but Ally is listed as controlling
musk thistle. The Escort formulation is also listed as controlling
Canada thistle as either a pre-emergent or early post-emergent treatment
for seedling weeds and as controlling hoary cress; but is not listed as
controlling either bull or musk thistle. Therefore, metsulfuron methyl
will mainly be considered for use in sites dominated by seedling Canada
thistle, not adult plants, where other problem thistles do not occur.
Because of its extreme phytotoxicity, its use will be avoided near
desired native or crop broadleaves. Also, repeated use of this or other
sulfonylurea and/or imidazolinone pesticides will be avoided so that
herbicide resistance does not develop in the refuge.

[2,4-D and Triclopyr]{.underline} (Crossbow or similar tank mix).
Crossbow is a preformulated mix listed as controlling Canada, bull and
musk thistles in rangeland and pastures. Reseeding cannot occur for 3
weeks due to soil residue activity. On an acute toxicity basis,
triclopyr ranks as moderately to highly toxic to mammals; slightly to
practically nontoxic to birds; and practically nontoxic to aquatic
species and bees (triclopyr amine salt). Thus, the main precautions will
be to protect applicator health during mixing. Like 2,4-D amine, the
half-life of the amine formulation of triclopyr is short, about one
week, in water. Therefore, use of this mix may be considered near
sensitive aquatic sites with no known mammals of concern. Since the
refuge has no experience with this mixture, it will probably only be
considered if other proposed control measures appear insufficient.

Triclopyr (Garlon) used by itself is labeled for and effective on brush
and some other broadleafs. Garlon 3A is labeled for elm, Canada thistle
and field bindweed, and Garlon 4 is labeled for salt cedar and elm. The
primary use of triclopyr on the refuge will be the control of invasive
woody vegetation.

[Dicamba/Triasulfuron ]{.underline}(Rave)- This tank mix is labeled to
control Canada thistle in grasslands, pasture, and fallow land. The
label stipulates avoiding use before target weeds are exposed to
extended freezing temperatures in the fall. Recropping depends on
bioassay results. Triasulfuron, also a sulfonylurea herbicide and ALS
inhibitor, is similar to metsulfuron in leaching characteristics (i.e.,
it is highly likely to leach in alkaline sites), although it is
apparently less persistent in water with a half-life of 1.7 weeks
reported at pH 7. A higher half-life is expected in the refuge's more
alkaline sites. On an acute toxicity basis, triasulfuron is no more than
slightly toxic to birds and mammals and practically nontoxic to most
aquatic species, but slightly toxic to bivalves. It is nontoxic to bees.
Dicamba is also rated as practically nontoxic to aquatic species and
birds, but slightly to moderately toxic to mammals. Unfortunately,
dicamba may be persistent in water (we were unable to locate degradation
rates), and therefore its use should be limited to small spot treatments
near aquatic sites, and only if glyphosate treatments fail. The refuge
has no experience with this pesticide premix in controlling Canada
thistle, but will consider its use as a follow up treatment away from
aquatic sites and sites with sensitive mammals if primary treatments
fail. The dicamba product, Rave, is also labeled as controlling musk
thistle and hoary cress. The refuge no experience with Dicamba, but it
may be considered as an alternative product in the future.

[Chlorsulfuron]{.underline} (Telar DF) - This is another sulfonylurea
herbicide with the same ALS mode of action. It is rated as being
practically nontoxic to aquatic species, birds, and mammals on a
short-term basis. However, chlorsulfuron is likely to leach easily and
persist for longer periods in alkaline sites, and appears to be the most
soluble of all the sulfonylurea herbicides listed. It is labeled as
suppressing but not controlling Canada thistle. As with other
sulfonylurea herbicides, there has been growing resistance of Canada
thistle to this herbicide. Its use on Maxwell NWR may therefore be less
desirable than other herbicides identified above.

[Imazapyr ]{.underline}(Arsenal) is an imidazolinone herbicide which
inhibits ALS, with a mode of action very similar to sulfonylurea
herbicides described above. It is listed as controlling bull and Canada
thistle in non-cropland, as well as field bindweed, Russian knapweed,
and yellow starthistle. Its use is restricted to utility, fence row and
other rights-of-way and similar sites, and to non-irrigation ditch
banks, so use of this herbicide will be restricted to such labeled
sites. However, on an acute toxicity basis, use of this compound would
be low risk to wildlife since it ranks as slightly to no more than
moderately toxic to mammals; no more than slightly toxic to birds; and
practically nontoxic to fish and invertebrates. The main problem with
imazapyr is that it is highly persistent in soil and maintains residual
activity, preventing its use in crop or restorations sites in which
grasses or broadleaves are desired. Imazapyr also does not hydrolyze
easily, but it does breaks down rapidly in sunlight, making it likely to
persist in groundwater and deep surface water, but not shallow surface
water. The evidence concerning this herbicide's leachability is
conflicting, but the substance has solubility characteristics that
suggest it is likely to leach. Therefore, use will need to be further
restricted near ground and surface water sources. The refuge has no
experience with this product, but it is a proven agent against salt
cedar, and may be used to control salt cedar on the refuge in the
future.

*Follow up Monitoring -* In addition to annual scouting for, and mapping
of, weed infestations, treated sites will be monitored to determine the
success of treatments, with the goal of measuring the degree of control
or suppression attained, expressed as the percent the stand was reduced.
Success will be measured based on revised estimates of the "acres
infested," as well as whether the treatment produced any undesired
effects on nontarget species or impeded grassland restoration through
residual effects. In addition to the acres infested, monitoring will
estimate the percent canopy cover of the infestation, providing an
additional measure of the effectiveness of control treatments.

**IPM Methods for Priority Species**

**Canada Thistle **

***Biology* - **Canada thistle (*Cirsium* *arvense*), a native to
southeastern Eurasia, is a highly aggressive, colony-forming perennial
in the aster family (Asteraceae). Canada thistle causes lumpjaw in
cattle and is a serious agricultural pest. Its leaves are considered
irritating to most grazing animals, including wildlife, and the plant
negatively impacts refuge crops and range sites by forming thickets
through vegetative growth, without the need for seed production,
crowding out other species. It can invade wet or dry areas in sandy,
silty, or clay soil types. It can also invade saline soils. Although it
primarily invades disturbed areas, including fields and roadsides, it
can also invade natural areas, including wetlands and grasslands.

In comparison with native thistles, Canada thistle are a darker green
plant with spiny, alternate leaves. Plants grow to a height of 2 - 4 ft.
On Maxwell Refuge, plants produce off-pink flowers in June and July.
Plants erupt and bolt in the spring to their full height with
spine-tipped, wavy leaves. The trigger is at least 14 hr of daylight.
This thistle develops a vigorous, extensive perennial root system that
extends both horizontally and vertically in the soil. Even fragmented
root parts from mechanical activities can result in production of new
plants, rendering mechanical methods ineffective. The only exception is
complete removal of young thistles in the early growth stage.

Plants spread either through vegetative growth from root material or, if
both male and female plants are present in a colony, by seed.**
**Patches on Maxwell seem to be reproducing vegetatively and may not be
producing viable seed.** **Canada thistles can produce up to 5000 seeds
per plant, but normally produce only about 1500. Most seeds remain
viable for only 2-3 years. Canada thistle are sun-loving and thrive in
disturbed or cultivated sites; shading by healthy native plants can be
an important limiting factor. Growth ceases at temperatures above 30^o^C
(= 86^o^F).

***Extent of Problem* - **This Class A weed is very widespread on the
refuge, infesting perhaps 500 acres or more. In year 2000 surveys,
infestations of this thistle were found in at least 17 of 55 farm fields
on the refuge (31%), as well as infestations of Canada thistle along the
face of dams, roadsides, and ditches and in surrounding areas. The
thistles are usually found in a cluster with a common root system,
appearing to spread vegetatively in most established clusters. Five of
the farm fields (B4 and B5, C1 and C4, and G) were so badly infested
that cropping practices have been drastically modified to emphasize and
facilitate "summer fallow" control activities.

***Treatment Goal*** - The treatment goal for Canada thistle is total
eradication of infestations in and adjacent to farm fields; control
infestations in range sites wherever they are located; and containment,
through perimeter control,** **of infested dam and ditch areas.

***Treatment Options and Selected Management Methods* - **Control of
this species will require at least a 3-5 year effort. Treatments will
focus on eliminating seed production and attacking the perennial root
system. As discussed above, manual and mechanical methods alone are
ineffective and may actually promote the spread of Canada thistle. An
exception to this rule is young plants without an established root
system, atypical of the perennial patches found on the refuge.

No biocontrol organisms imported to date to control Canada thistle have
been highly effective. The seedhead weevil, *Rhinocyllus conicus*, whose
larvae forage on thistle flowers, reducing seed production, is sometimes
partially effective on Canada thistle, and to a lesser extent, musk
thistle. This species is less effective on bull thistle. Unfortunately,
this species also attacks native thistles and poses a risk to their
populations. Its use would be inconsistent with protecting native
thistle species in New Mexico, some of which are declining or rare.
However, the seedhead weevil has become established locally and will
likely become part of the refuge fauna in the near future, if it has not
already. Field scouting efforts should include attempts to document the
presence of seedhead weevils or their larvae. The gall fly, *Urophora
cardui,* may also assist somewhat in limiting Canada thistle
populations, but supplies of this organism are not easily obtained. The
Refuge will consider introducing this organism as a supplemental
treatment if a supply of this becomes available.

Prescribed burning, or prescribed burning followed by an herbicide, have
been suggested as treatments to reduce the number of mature plants,
limit seed production, and foster native grass growth ( However, this
method is ineffective on many other invasive species on the refuge,
including musk thistle, and may actually enhance the seed germination of
such species, especially on the disturbed sites typically found on the
refuge. Fire will therefore be considered as a viable management tool
only on range sites that have been successfully restored and where
invasives are not a particular management concern.

Repeated monthly mowing of Canada thistle over long periods of time has
been demonstrated to control Canada thistle, but this method is not
feasible on most sites, especially range sites, due to the size of the
area involved and the staff hours required. Mowing or cutting do provide
additional stress and may improve the efficacy of herbicide treatment.
Good regrowth (4-6 inches) after mowing of the thistle is recommended if
a systemic herbicide is to be applied (4 weeks or so). Therefore, mowing
or cutting will be used on selected, accessible sites in advance of
herbicide treatment as part of this refuge's primary control strategy.
In areas with substantial overstory, a bush hog will also be used to
remove the over-lying vegetation to aid in visually locating thistles
and improve herbicide effectiveness, whether by hand-held spot treatment
or over-the-top boom application.

The selected preferred alternative along roadways and in natural areas
is boom and/or spot spraying with a tank mix of 2,4-D amine and
clopyralid (Curtail or an equivalent tank mix), using an ATV with a
small mounted tank and/or a backpack spot sprayer** **at a rate of 2-3
qt/acre (Note that the nozzle on the 14 gallon sprayer used on the
4-wheeler puts out about 40 gallons per acre). If evaluations of
wet-blade mowing from 2001/2002 trials indicate good efficacy and if the
WetBlade mower remains in good repair, this mower will be used to reduce
herbicide use, especially in accessible, sensitive sites.
Difficult-to-treat thistles may receive a follow up tank mix treatment
such as with a tank mix of picloram, 2,4-D, and clopyralid or
triasulfuron methyl and dicamba, depending on location and previous
control effort results. Selected, small, isolated patches of Canada
thistle that are not in sensitive sites may be spot treated by hand with
the picloram tank mix used for Russian knapweed.

Preferred methods will be modified in wet sites, sites immediately
adjacent to springs, tanks and water bodies, and in other sites
considered **sensitive**. At wet sites, a glyphosate treatment with
Rodeo will be used in place of clopyralid and/or 2,4-D. In drier highly
sensitive sites, Roundup, also a glyphosate formulation, may also be
used. Cutting or mowing prior to herbicide treatment will be used to
increase efficacy when practical.

Cropping practices in infested farm fields will be modified to
facilitate treatments, including summer fallow of heavily infested sites
(e.g., C1 and C4). In these sites, repeated mowing or discing will be
used to interrupt the bloom cycle and stress the energy reserve in the
roots. This will be followed by herbicide applications to attack the
stressed roots. A late-season boom treatment with Roundup (½ pint to1
pint per acre) at the early bud stage is scheduled for field testing on
these fallow crop field sites in 2001. Caution must be exercised when
discing any area with a perennial rooted invasive to clean the equipment
before leaving the field.** **The light concentration is essential so as
not to top kill the plant before the plants have the opportunity to
translocate the glyphosate to the roots. Trials to increase efficacy
will use ammonium sulfate to maximize the success potential with
glyphosate products. Also, to the maximum extent possible, the refuge
will attempt to treat Canada thistle when plants are growing best, and
when soils are moist. Otherwise, the fall period would be considered
optimal since this is when plants are translocating nutrients and would
also be translocating the most herbicide down to the roots, in theory. A
winter crop of green feed (wheat) can be planted after this treatment,
but the field should not be disced until total brownup occurs to avoid
limiting the treatment to a topkill, and a notill planting would be
preferable. Fields with smaller, isolated infestations, such as B4 and
B5 may be summer fallowed and treated in this manner in future growing
seasons to control patches of thistle.

Table 3 indicates the following additional herbicide treatment options:
metsulfuron-methyl; a dicamba/triasulfuron tank mix; chlorsulfuron; a
2,4-D/triclopyr tank mix; or imazapyr, as being effective on Canada
thistle. Maxwell NWR has no experience with which to evaluate efficacy
of these options, but will consider their use in future years if the
treatments proposed above fails and pilot trials do not indicate desired
efficacy. Imazapyr has a long residual and may have limited uses, such
as along fences and rights-of-way.

In addition to herbicide treatment, an important component of successful
IPM for Canada thistle will be the purchase of weed-free seeds for use
in agricultural sites and reseeding of grassland and disturbed sites
with native species that can compete with and shade out the thistle.
Prescribed burning, grazing or other forms of disturbance will be
avoided until infestations are controlled and sites are successfully
restored to healthy native vegetation.

**Musk and Bull Thistles**

***Biology -*** The New Mexico Department of Agriculture has identified
musk thistle as a Class B weed. It shares many attributes in common with
bull thistles. Both thistles are invasives, native to southern Europe
and western Asia. Like Canada thistle, musk thistle (*Carduus* *nutans*)
and bull thistle (*Cirsium* *vulgare*) cause lumpjaw in cattle and are
serious agricultural pests, in addition to adversely affecting refuge
crops and range sites. However, unlike Canada thistle, these species are
biennials that develop annual tap roots, but lack the perennial root
system of Canada thistle. Both have pink to purple flowers, although
musk thistle can occasionally have white flowers.

Musk thistles have alternate leaves with spiny margins that clasp the
stem; rosettes are smooth to densely hairy. Mature plants can reach 6 ft
in height and have a fleshy taproot. This species has the potential to
spread much more rapidly** **than Canada thistle due to its seed
dispersal capabilities combined with its tremendous seed production (as
mush as several thousand seeds per large plant). Seeds remain viable for
up to 10 years. Although most easily established on bare soil or cracked
soil, the plant can invade wetlands, grasslands, crop fields and other
sites.

Growing in moist to dry soils of all textures, bull thistles can produce
up to 4,000 seeds per plant. This thistle thrives on nitrogen-rich soils
and is controlled by shading and or repeated cultivation. Like Canada
thistle, musk and bull thistles form rosettes before bolting and
flowering. Rosettes are more susceptible to uprooting and to chemical
treatment; however, their prostrate growth habit makes them difficult to
detect. The presence of the similar native wavyleaf thistle (*Cirsium*
*undulatum*) should also be noted and will not be targeted for control.

***Extent of the Problem*** - Musk thistle is even more widely spread
than Canada thistle on the Refuge, but has not succeeded in taking over
any individual crop fields yet. The worst loci of musk thistle
infestations are currently found in abandoned fields and other range
sites. A 5-inch rain in May 1999, together with no effective control
that year, resulted in a huge seed crop that will continue to produce
seedlings that form rosettes until perhaps 2009. Musk thistle
infestations were so numerous in 2000 that there was insufficient time
to treat all of them prior to flowering. Despite very successful control
in 2000, infestations will probably continue to be large due to a
significant seed bank earlier years. Bull thistle is much more sparse in
distribution and overall numbers, and seems to like the moister sites
below dams best.

***Treatment Goal* - **The treatment goal for these thistles is total
elimination in and around crop fields. In noncrop areas, scouting will
occur throughout the refuge to locate and treat musk and bull thistles
before they flower annual scouting, monitoring, and follow up control
treatments will also occur, with the goal of elimination of isolated
individuals and control of larger infestations in range and other
non-farm sites.

***Treatment Options and Selected Management Methods*** - Many years of
control efforts may be required because of the lengthy seed viability.
Manual/mechanical treatments are equally ineffective in controlling musk
thistles as in controlling Canada thistle and the effect of fire is
unknown. Mechanical control alone has proven to be ineffective at
stopping seed production as

cutting off the plant above the rosette will not kill the plant and will
hasten the development of buds and flowers as the plant becomes
stressed, requiring a follow up treatment of herbicide such as 2, 4-D.
This mow, wait, and spray sequence, when mowing is done before seed set
occurs and 2, 4-D is applied with a boom sprayer before flowers are set
after regrowth, was proven to be extremely effective in controlling both
first and second year thistles in 2000.

Musk and bull thistle patches that have started to go to seed should not
be mowed as the action will only spread seeds and seed heads. In fact a
plant with a maturing seed head will attempt to make seed if it is left
attached to the plant. Where only a few individuals occur, young plants
without flowers may be dug up at a point 2 inches below the rosette. If
musk thistles do flower and set seeds, the seed heads can be pruned off,
collected, and incinerated before seed drop occurs. Although this
pruning method is also very labor intensive, it is the only way to
eliminate seeds after seed set has occurred. These methods will be
supplemental, at best, since this prostrate growth form is difficult to
detect from any distance and sufficient staff for large efforts are
unlikely. This method may also be used in sensitive sites, such as
around seeps or open water.

Because these thistles can be intermixed with Canada thistle, identified
as the Refuge's top priority species to control, and generally
susceptible to the same treatments, the same herbicide treatments
proposed for control of Canada thistle can be used to control musk and
bull thistle, with glyphosate, 2,4-D/clopyralid, and
picloram/2,4-D/clopyralid tank mixes proposed depending on type of site
and alternative herbicides proposed if the above treatments fail to
provide needed efficacy or if populations become resistant. (For rates,
see Canada thistle.)

For individual musk thistles and small or scattered stands, treatments
with 2, 4-D early in the growing cycle are preferable, typically through
hand held spot treatments form a 4-wheeler. If flower development has
begun (late May or later), 2,4-D mixed with chlorsulfuron or metsulfuron
will be used to arrest seed development in these sites. For large stands
and when areas with maturing flowers can not be sprayed, the site will
be mowed (before seed set has occurred) and then sprayed 2 to 3 weeks
after mowing**.** Bull thistle will be treated in the same manner as
musk thistle.

Careful monitoring and record-keeping will be used to track any
herbicide resistant patches, and the refuge will attempt to alternate
treatments from those of the previous year at such sites. Treatment
opportunities will expand once Canada thistle is eliminated from sites.
For example, 2,4-D and chlorsulfuron may also be used for spot
treatments or when musk thistle is the dominant species. This treatment
was effective even where flower development was advanced beyond the bud
stage, and, therefore, this combination will be used in cases where musk
thistle are beyond bud in order to inhibit seed production.

Another herbicide identified as effective on musk thistle is dicamba at
1 lb/acre or a combination of dicamba and 2,4-D. Dicamba is not
effective on Canada thistle; therefore its use will likely be limited
until Canada thistle is fully controlled.

Two biocontrols are available that could assist in musk thistle control,
*Rhinocyllus conicus, *and *Trichosirocalus horridus*. Only the former
is widely available, but this weevil species will also attack native
thistles and therefore has been rejected from consideration for now.
However, populations of *Rhinocyllus* are know to be in the area in
Colfax County, and can be expected to populate the refuge in the future.

Minimizing disturbance and reseeding bare ground areas will also be
important elements of thistle control and grassland restoration.
Therefore, use of prescribed fire or grazing livestock was not
considered a viable option for invasive weed control. Use of weed-free
seed is an important preventative measure during both crop and grassland
seeding.

**Russian Knapweed **

***Biology -*** Russian knapweed (*Centauria* *repens*) is a perennial
with a reputation for toughness in resisting control treatments. A
single Russian knapweed plant has been reported to have spread over 14
yd^2^ in two years, averaging a linear rate of over 10 feet each year.
This knapweed species normally forms dense clusters with a common root
system, although there are exceptions on the refuge with scattered
stands of individual plants several feet apart west of Lake 14, across
from Headquarters and southeast of Lake 12. It is chemically active,
causing dermatitis to humans, toxicity to equines, and exhibits
allelopathy. While it freely expands stand size vegetatively, it is also
good at pioneering new sites through transported seed, as it is all too
commonly found along roadsides. The New Mexico Department of Agriculture
has identified Russian knapweed as Class B weeds. Russian knapweed can
be very hard to detect from any distance unless in bloom (June and
July).

***Extent of Problem* -** Numerous sites were detected with relatively
small infestations of Russian knapweed in 2000, an invasive species
previously unknown and untreated on the refuge. These sites were located
in a curious variety of locations, including mostly roadsides, but also
in G field, and additionally in some range sites without a clear
connection to a source of seed or root material. Large stands exist
northwest of Lake 14 or in the triangle southeast of Lake 12 (both in
atypical, scattered stands). This highly invasive species is also
especially prolific in fields G and A. It is likely that perennial
species such as Russian knapweed will continue to expand its
infestations at a rate of 5-10 feet or more per year at Maxwell NWR, if
control measures are not continued.

***Treatment Goal* - **The treatment goal for this species should be
total elimination for all infestations, owing to the relatively few
sites and small acreage infested, combined with its proclivity for
pioneering from seed. In 2001, two fields (A and G) were infested, with
G having the most serious portion of the field involved. Infested fields
will be fallowed to facilitate treatment and promote visibility of the
infestation. Monitoring in May 2002 indicated that the G field
infestation was relatively healthy, but the infestation in A Field, like
other sites treated with the picloram tank mix, with decreased by over
90%.

***Selected Management Methods*** - Either picloram or tank mixes with
picloram (2,4-D / Clopyralid/Picloram) were identified as the only
effective treatments among trials conducted in 2000. All leaves must be
sprayed until wet, or treatments will be less effective. The WetBlade
also has potential in these treatments, and should be field tested on
large stands, such as those northwest of Lake 14 or in the triangle
southeast of Lake 12. The above herbicides will also be used for
treatments of fields A&G and for spot treatment of isolated individuals.
If these treatments are unsuccessful, metsulfuron methyl will
substituted. Along fence lines and right-of-ways, imazapyr may also be
used. Note that a general application of any picloram to a crop field
will require that field to be fallowed more multiple years, suggestion
that a hand held spot treatment to individual knapweed plants might be
best in crop field situations. Care must also be taken not to disc the
field so as not to spread and invigorate the root system, an unfortunate
practice demonstrated by the extent of the infestation in G Field.
Fallow, Spot Spray, No Till.

**Hoary Cress**

***Biology -**** *Hoary cress* (Cardaria draba)* is a perennial that
forms clustered stands spreading from a common root system. This species
can also spread from root fragments or seed, making discing an effective
dispersal method and a totally ineffective control method. It is similar
to perennial pepperweed, also sometimes called whitetop, and also to
hairy and lens-podded whitetop because of white flower clusters at the
tops of the stems. However, it can be distinguished by its heart-shaped
seed capsules. This invasive weed produces flowers earlier than any
other invasive species on the refuge. The plant is in the bud stage from
late April to early May, the earliest of all refuge invasives, and
infestation are best found by scouting while the patches are in bloom.
Seed set occurs by early summer.

***Extent of the Problem - ***Infestations of this plant are primarily
associated with irrigation ditches on Maxwell Refuge, but have also
spread extensively into surrounding upland areas, highway right-of-ways,
and roadsides. In 2000, we located three sites in range situations and a
small colony on the south end of Field F2. Hoary cress is now also well
established in fields B5 and F1, and other sites were found in scouting
in 2001. We believe that hoary cress is expanding its infestations in
the range of 5 to 10 ft/year at Maxwell, requiring prompt and effective
control treatments to keep the problem manageable.

***Treatment goal*** - The treatment goal is total eradication of all
stands in all locations, including preventing seed production and
avoiding the spread of root systems and other plant parts by other
operations. Also, as with other invasive species, working with neighbors
and other agencies to become aware of and take effective action against
this invasive must be part of the overall solution For example, the
practice of mowing roadsides is helping to rapidly spread infestations,
whereas if patches were spot treated before seed production and
top-killed, mowing later would not be a problem.

***Selected Management Methods**** - *Because it is the earliest
priority weed to flower and is difficult to locate when it is not in
flower, scouting and treatment will occur beginning in April, when the
hoary cress are in bud or flowering. The ideal treatment stage is "bud
stage" so mapping and the use of a GPS unit will be used to relocate
patches for treatment in future years before they reach full bloom.
Hoary cress resisted treatment with 2,4-D mixed with metsulfuron methyl
(Escort) in 2000, so different treatments may be needed in monitoring
indicates that follow up treatments in 2001 were also unsuccessful in
preventing regrowth the following year.. Prior treatments with
metsulfuron methyl were only effective in top-killing the stand, but the
lack of control on root systems may owe to the late period of
application relative to the bloom cycle in 2000. Therefore, field trials
will be established during bud stage to compare the efficacy of
metsulfuron methyl or chlorsulfuron with other products listed in Table
3.

**Saltcedar**

***Biology - * **Saltcedar, also known as** **tamarisk *(Tamarix*
*ramosissima*), is a highly invasive tree species that can grow to 20 ft
or more in height. The plant is a deciduous evergreen from Eurasia that
has now become a serious problem throughout the West, especially in
riparian areas along streams and canals, reservoirs and other water
bodies. Saltcedar displaces native tree species, such as cottonwood, by
exuding salts that are phytotoxic, and they alter hydrology because of a
larger water demand than native riparian species. Hence, sites infested
with saltcedar are sometimes difficult to restore.

***Extent of the Problem**** - *Until recently, saltcedar only occurred
on Maxwell Refuge as scattered saplings and isolated trees, and all of
these were thought to be controlled due to aggressive treatments in 2000
and 2001. However, by fall of 2001 an extensive eruption was detected
around lakes 12 and 13, likely dating to the flood of May 1999, wherein
tens of thousands of seeds came into the refuge from upstream (including
Stubblefield Reservoir) and germinated. This species will remain a
priority for control due to its extreme invasiveness, high water demand,
and potential for erupting in mass quantities, and the likelihood of
continued new infestations via upstream water deliveries. Salt cedar has
become well established off the refuge in the Vermejo and Canadian
watersheds, including the Vermejo Conservation District Dam reservoir
and canal system that feeds into the refuge.

***Treatment Goal*** - Total eradication in all sites. All mature plants
were killed by 2001, but thousands of seedlings and saplings persist.

***Selected Management Method*** - As with other invasives, annual
scouting efforts in all likely moist areas of the refuge will occur
during the spring growing season to locate any new infestations. Younger
stands of this species will be mowed or cut with the WetBlade. The
refuge has been highly successful in using Garlon 3A and Garlon 4, and
will continue to use these products and spot treatment methods. Garlon 4
(triclopyr butoxy ester) ranks as moderately toxic to highly toxic to
mammals; slightly to practically nontoxic to birds; highly toxic to
fish; and highly to practically nontoxic to aquatic invertebrates
depending on species. For this reason, applications of Garlon 4 will be
limited to cut stump treatments and basal bark spot sprays. Garlon 3A,
an amine salt formulation, is used in sensitive sites near water since
it is lower in toxicity to fish and aquatic invertebrates. On an acute
toxicity basis, it ranks as practically nontoxic to fish and aquatic
invertebrates and similar in toxicity to birds and mammals.

Imazapyr (Arsenal) in dry sites, and Glyphosate (Rodeo) in wet sites,
may also be used to control salt cedar. Bosque del Apache refuge has had
good success with these products, including using them in combination.
Innundation is not a viable control option for salt cedar at Maxwell due
to the elevation of the infestations and the long duration of complete
submersion needed to kill the plant and root system. Working with the
Vermejo Conservancy District and other refuge neighbors towards the
control of cedar and seed sources will be an important part of an
effective salt cedar control program.

**Russian Olive**

***Biology - ***This tree species (*Elaeagnus angustifolia*), introduced
from Europe as an ornamental, grows to a height of 25 ft and is armed
with 1-2 inch thorns. Although it is recognized as a source of food and
habitat for wildlife, it invades moist rangeland, meadows and waterways,
and can become a serious weed problem in New Mexico riparian systems. It
may be the only plant capable of displacing salt cedar infestation in
riparian situations.

***Extent of the Problem*** *- *A few Russian olives were planted in the
headquarters area several years ago, with only a single escaped olive
sapling located and killed in 2000.** **Due to control efforts in 2000
and 2001, Russian olive are thought to be eradicated from the refuge,
although it is likely that American robins and other seed eating birds
may reintroduce seed from infestations along the Canadian or Vermejo
Rivers, requiring continued monitoring and treatment.

***Treatment Goal*** - Total eradication in all refuge sites. Work with
neighboring landowners to reduce or eliminate offsite seed sources.

***Selected Management Methods -*** The same methods will be used as for
saltcedar (see above).

**Siberian Elm**

***Biology**** - *Also known as Russian elm (*Ulmus* *pumila*).
Introduced by settlers for shade and as a windbreak around areas of
habitation, this non-native tree is capable of spreading vegetatively
though suckers and by seed.

***Extent of the Problem *-** Scattered groves of this elm remain on the
refuge on former home sites. These elm stands are spreading moderately
across the refuge landscape either through vegetative suckers or seed
dispersal, and are overtaking other habitat types.

***Treatment Goal*** - Control the expanding new growth from existing
stands by mowing and or herbicide application and or cut stump treatment
with chainsaw. The removal of all trees is not considered desirable or
necessary as long as expanding growth is culled every few years, which
was never done until 2000.

***Selected Management Methods**** - *Siberian elm will be controlled by
methods described above for saltcedar; mowing, spraying, or cut-stump
treatments. Mowing younger saplings and touching up regrowth with 2, 4-D
or Garlon will likely prove to be the easiest and most efficient means
of control.

**Grasshoppers**

Northeastern New Mexico hosts as many as 70 species of grasshoppers.
Known for their cyclic population eruptions and voracious appetites,
grasshoppers can decimate any edible forage. Refuge crops, including
cooperative farmers' alfalfa fields, are grown to help meet refuge
purposes by providing forage for migratory birds. Fields planted in
irrigated crops are a particularly susceptible source of food for
foraging grasshoppers, and previous infestations have caused serious
damage to refuge crops.

***Biology -*** Because of the large number of species, individual
biologies will not be discussed in detail here. Information on
individual species is summarized in "Multiyear Evaluation of the Effects
of *Nosema* *locustae* on Rangeland Grasshopper Density and Natural
Biological Controls," by Bomar et al. (1993)** **and readers are
referred to this document. The most common species encountered by Bomar
were *Melanoplus bivitatus*, the two-striped grasshopper, *M.
femurrubrum*, the redlegged grasshopper, and *Phoetaliotes
nebrascensis*, the largeheaded grasshopper. These are all spurthroated
grasshoppers.

It is important to emphasize the different dietary preferences among
grasshopper species and preferences in consumption of wheat bran bait,
or not, when considering treatment options. The spurthroated
grasshoppers do eat bran baits. Some species have relatively narrow
dietary preferences and eat only grasses, while other species have a
wider dietary range, eating grasses and other plants, and not all
species will be attracted to a bran bait product. Thus, the species
composition involved in an infestation is important in considering
control alternatives and locations.

Another important factor to consider in applying treatments is that not
all growth stages, or instar, will eat the bran bait. The third and
fourth instar stages of slantfaced grasshoppers will forage on bran
bait, thereby infecting the population. Other stages, including adults,
do not eat bran bait. However, adults may become infected with *Nosema*
if they cannibalize other dead or dying grasshoppers that have consumed
bran bait.

***Extent of Problem - ***Maxwell NWR has experienced multiple**
**grasshopper outbreaks, involving various species listed above,
including outbreaks of those of grasshopper species that do eat bran
bait, but also species of other types of grasshoppers, including
bandwinged and slantfaced grasshoppers. Prior treatments with two
different *Nosema* bait products, each used on separate outbreaks, have
been mixed. The *Nosema* product used in the Bomar study gave good
results, while the other used by the refuge in later outbreaks, did not.
While it is unclear as to why the later treatment was ineffective,
product freshness may have been a factor.

***Selected Management Methods - ***In the future, Maxwell NWR will
utilize three distinct types of control for grasshoppers: cultural,
biological and insecticidal. Prior to initiating controls, the following
scouting protocol will be conducted to monitor the distribution,
abundance, species, and growth stage of infestations.

[Scouting]{.underline} - The decision to control a grasshopper
infestation will depend on 1) the dominant grasshopper species present
and its (their) dietary preferences and propensities to cause crop or
natural resource damage; 2) established action thresholds based on
scouted grasshopper densities, and 3) whether biocontrol with Nosema
bait, the first selected line of defense, is likely to be effective or
not.

Thus, species identification and scouting will be crucial elements of
the refuge's IPM program, and treatment will only occur to threatened
sites. For example, for grass-eating grasshoppers, control efforts in
and around alfalfa fields would be unneeded and a wasteful use of
control agents, whereas treatment might be necessary in grain crop
situations (e.g., wheat and corn). Also, if an infestation is comprised
of species that do not eat oat bran (e.g., various species of
"slantfaced" grasshoppers), then the application of a bran bait product
is not a viable option for control, and other strategies must be
applied.

Scouting for grasshoppers will begin when warmer spring conditions
arrive, with efforts concentrated in areas likely to host grasshoppers.
Scouting will occur on warm afternoons when grasshoppers are most
active. Soil temperatures will also be monitored to predict emergences.
When grasshoppers are detected, a weekly scouting schedule will be
established (preferably on Monday afternoons) to determine grasshopper
densities. Densities will be recorded and correlated with soil
temperatures recorded at these same sites.

Standardized sampling will be conducted in following with guidelines
developed by Patrick (1998), Extension Entomologist with the Texas A&M
University System, using the square foot method, as follows:

Within the sample area, the number of grasshoppers in an estimated
square foot will be counted using a hand counter and recorded in 18
quadrants 20 paces apart. \[Persons conducting these sampling counts
will initially practice with a measured square foot until they become
proficient at visually estimating that size area accurately.\] The total
number of grasshoppers will be divided by two, providing an average
number of grasshoppers/yd^2^ (=9 ft^2^). If the grasshoppers are
predominantly in the first to third instar (wingless and generally less
than ½ inch long), the number will be divided by three to get the
equivalent number of adults when an insecticide control is under
consideration. Individuals in the fourth instar and up will be
considered adults. This determination will be made based on species
identification, species ratios, growth stage (instar), and action
thresholds for the dominant species. To determine thresholds for
biocontrol, immature instar will be counted as one. Specimens will be
collected and identified to determine species. Dietary preferences will
be determined from previously collected data . Related data will be
collected for future reference and to refine control strategies.

A minimum of four areas representing different geographic locations and
habitats on the refuge will be sampled using this method, generating
count data for a total of at least 8 yd^2^ (72 ft^2^). Sampling will
occur in at least one non-barley crop location, one barley planting, and
one non-crop range site. The sample from the barley planting will not be
weighed into the overall average used to determine threshold levels,
assuming that the barley will have few, if any, grasshoppers. However,
sampling here will indicate whether grasshoppers are using the barley
and whether the barley is an effective cultural management strategy.

The following action thresholds, based on those developed by Patrick,
will serve as initial guides for insecticidal treatments. The threshold
ratings are split into two categories, one for fields, which includes
rangeland and field crops, and the second for margin areas outside
fields, as follows:

**Infestation Adult Count Adults In Margin **

** (No./yd^2^) (No./yd^2^)**

Non-Economic 0 - 2 5 - 10

Light 3 - 7 11- 20

Threatening\* 8 - 14 21 - 40

Severe\* 15 - 28 40 - 80

Very Severe\* 28+ 80+

Infestations at or above the "threatening" level will be considered
candidates for the application of insecticide (\*). A *Nosema* bait will
be used on "light", or possibly the higher end of the "non-economic"
range of infestations, on species which consume bait. Patrick's ratings
and associated thresholds do not identify the infestation level
warranting the application of biocontrol agents and may not reflect
future cost effectiveness and/or refuge management goals. An additional
factor to consider in the pondering the threshold to spray or not is the
negative effect of an insecticide on non-target insect species, some of
which may be beneficial (pollinators, beneficial predators, etc.).
Hence, some experimentation with these thresholds will be done to assess
*Nosema* effectiveness on various grasshopper species and adjust for
detected benefits or adverse effects of any chemical uses on refuge
trust species.

[Cultural Control]{.underline}. The main cultural control will be the
planting of barley, since prior refuge experience has observed some
avoidance of this crop by grasshoppers, and it aids in meeting the
dietary requirements of migratory waterfowl. Each winter, in the
development of the Annual Crop Rotation Plan for the upcoming planting
season, the acreage of barley grown as either a green browse and/or
grain crop will be maximized. Additionally, barley will be planted as a
buffer surrounding other crops in an effort to shield these crops from
infestations. These buffers will be maximized, as reflected in the crop
plan and in coordination with refuge cooperative farmers.

[Biocontrol.]{.underline} The protozoan *Nosema* *locustae* is available
as a wheat bran bait in multiple control products (such as NoloBait and
Semaspore). This product will be used as the refuge's first line of
defense if grasshoppers are in the 3^rd^ and 4^th^ instar stages when
the grasshopper species of concern actually have a dietary preference
for bran bait (provided that the bait can be obtained from a supplier in
a timely manner). An advantage of this product is that, if it infects a
grasshopper population successfully, it can spread among grasshoppers,
infecting subsequent generations and providing long-term control. In the
future, the refuge will also evaluate use of two other potential
biocontrols: a fungal product, Mycotrol, and the parasitic wasp, *Scelio
opacus*. As with other control agents for other species, refuge
management will be on the lookout for other biocontrol agents for
grasshoppers to add to the "toll box" used for integrated control
efforts.

The *Nosema* bait has a short self-life and is susceptible to heat
damage; therefore the product will be ordered as needed and put out with
urgency, but never stockpiled. Optimal efficacy from *Nosema* may not be
reached until 4 to 6 weeks after application. Consequently, regular
scouting will continue to monitor the grasshoppers to assure that the
population is not erupting, triggering the need for an insecticide. The
refuge will also continue evaluating the effectiveness of *Nosema* and
adapting the proposed scouting protocol, if needed to evaluate off-site
source grasshopper sources. If scouting and use of *Nosema* and other
possible biocontrols is ineffective, then chemical control will be
implemented.

[Chemical Control]{.underline} - The use of insecticides to control
grasshopper outbreaks raises significant issues, especially in the
context of Federal land managed as a National Wildlife Refuge. The
primary consideration is toxicity, not only to non-target insects, but
to native species and species biodiversity, as well as to health and
safety of refuge staff applying the pesticide. Repeated applications and
reliance on a chemical solution may result in the buildup of undesirable
chemical residual in the environment or cumulative effects on biota, in
addition to a buildup of resistance in the target population.

Three products will be considered for treatment of the grasshoppers:
carbaryl (Sevin), Malathion, and pyrethrin. In the future, a new
low-risk insecticide, Spinosad, may also be considered. However, it is
not yet labeled for refuge crops or rangeland. Characteristics of
carbaryl, the preferred insecticide, is reviewed below:

[Carbaryl (Sevin)]{.underline}. Carbaryl is a carbamate insect that
causes acetylcholinesterase (AChE) inhibition, affecting nerve function
in insects, and to a lesser extent other vertebrates. Among vertebrates,
fish and frogs are especially sensitive to exposure to carbaryl.
Repeated exposure at close frequency causes cumulative impacts to the
central nervous system of vertebrates, and, if sufficient, can result in
behavioral changes, convulsions and death. However, AChE inhibition by
carbamates, unlike organophosphates, is reversible withing a period of
days to weeks, limiting impacts except On an acute toxicity basis, both
carbaryl and breakdown product, 1‑naphthol, are rated as moderately to
highly toxic to fish; moderately toxic to mammals; and slightly to
moderately toxic to birds. Therefore, this product poses some risks to
refuge resources. Fortunately, carbaryl degrades rapidly in soil and
water, with a typical half-life in the range of 2-9 days on treated
plants; one-two weeks on sandy loam soil; and about half a day in waters
of pH 8 or higher.

Carbaryl ( in this case, Sevin XLR) will remain an important defense in
an integrated approach to managing grasshopper outbreaks, considering
the potential for devastation resulting from high grasshopper densities.

**Prevention**

The ultimate control action against invasive plant species on Maxwell's
rangeland will be to reestablish healthy native short-grass prairie
plant communities. Therefore, the rehabilitation of abandoned crop
fields and overgrazed range sites is in itself an important component of
this IPM plan. However, the Refuge also intends to aggressively scout
for, and eliminate, any new individuals or colonies of priority species
that may recolonize refuge lands. Post-application monitoring to
evaluate effectiveness and detect possible regrowth that may require a
touch-up application will be a routine practice on Maxwell Refuge.

In addition to the priority weeds identified above, Maxwell Refuge
intends to prevent the invasion and proliferation of invasive species
likely to pose future problems to the refuge if not controlled
immediately. Species in this category include *Halogeton*, leafy spurge
and yellow starthistle. *Halogeton* can cause liver damage in livestock.
Yellow starthistle is toxic to equines, causing chewing disease and
possibly death. Leafy spurge is already established in Colfax County.
Typically, these invasive plants, native to Europe or Asia, have found a
variety of niches to exploit, frequently in disturbed sites. Maxwell NWR
staff, volunteers, and visitors will be trained to recognize these
species and instructed or asked to remove any of these species found or
to notify the refuge manager of their location. Removal actions will
occur immediately following documentation, including mapping with Global
Positioning System.

Another aspect of prevention will be refuge emphasis on weed control
along roadsides and irrigation ditch banks, in addition to refuge crop
fields, since these are key production areas of seeds of invasive weeds,
and seeds from these sites are especially likely to be transported by
vehicles or water to other locations.** **Cleaning vehicles and
equipment that is to be transported off refuge or brought onto the
refuge is another important part of employing integrated cultural
controls.

Farmers will also be requested to use weed-free seed. This will become a
requirement in new farming agreements. In addition, farmers will be
encouraged to select crop varieties that are resistant to any new insect
or fungal pests encountered in the future, and** **farmers will be
encouraged to time their cuts so that it occurs before weed seed
production.

All equipment used off-road or in the field, including tractors,
4-wheelers, trucks and fire equipment, will be thoroughly cleaned with
high pressure spray equipment before being taken to another location
away from the station. Likewise, any equipment coming to the refuge from
another area will be cleaned before arriving at Maxwell, preferably at
its origin.

**Outreach & Coordination**

Since the ecosystem and the pest plant invasion do not start or stop at
the refuge boundary, working with neighboring landowners and other
partners in the community (e.g., Colfax County, the County Extension
Agent, Highway Department, and Vermejo Irrigation District) is vital in
the successful management of invasive plant infestations both on and off
Service lands. Organizing and/or participating in the Colfax County weed
workgroup is providing a good vehicle for outreach and coordination on
weed control and related issues and will continue.

In addition, Maxwell Refuge will familiarize all permanent and seasonal
staff with the Refuge's invasive species control program, and will
produce bulletins and pictures of unwanted invasive species, enabling
staff, volunteers, and visitors to assist in its control efforts.
Infestations of invasive species and their management will be an
important subject for interpretation to refuge visitors, as well as to
refuge neighbors and the community in general. Staff, volunteers, and
visitors will also be encouraged to opportunistically uproot and
properly dispose of easily recognized invasives or assist in cutting and
other non-pesticide aspects of their control.

**Summary of the Preferred Alternative**

The preferred alternative for pest management at Maxwell National
Wildlife Refuge is to implement aggressive IPM control strategies,
including the minimum amount of effective herbicide(s) needed to produce
the desired measure of control over invasive plant infestations. The
refuge will employ combinations of biological, cultural, mechanical,
herbicide and insecticide treatments that represent the best management
practices available, based on current science and sound ecological
principles, based on ample amounts of scouting and monitoring. Special
attention will be paid to the availability of new biocontrol agents and
new low-risk control agents, and to the most up-to-date equipment needed
to ensure effective, environmentally responsible treatments.

Efforts will continue to identify invasive plant infestations and map
infestations has been initiated and will be completed at the earliest
opportunity. Although the vegetation survey conducted in 1999 produced a
map, infested areas are identified with the generic, nonspecific term
"herbaceous disturbance", with no reference as to the species present.
Completing a comprehensive mapping effort in digital format, including
an estimate of acres infested by each species, will provide a sound
foundation to work from, as well as a meaningful tool from which to
measure the success of subsequent treatments. Annual scouting efforts in
all areas of the refuge during the spring growing season will reveal new
infestations, likely reducing the intensity of new infestations and the
resources required to eliminate future infestations.

Selective use of effective herbicides, or herbicides in combination with
mowing, will provide the desired measure of control that is targeted for
each species of invasive plant and agricultural weed. Refuge management
treatments for pest plants will be implemented on a priority basis,
ranging from total elimination, to control, and including suppression,
and containment, as follows:

-   eliminate all newly discovered invasive plant infestations, and
    eliminate all infestations of invasive plants in and adjacent to
    farm fields, as rapidly as possible.

-   control all existing infestations of invasive plants in range sites
    and along roads.

-   control or suppress other agricultural weeds in farm fields.

-   contain invasive plants around District dams and in District
    ditches.

Treatments will be scheduled to eliminate seed production. If, for some
reason, an entire infestation can not be treated, the perimeter of the
infestation will be treated to contain and minimize the expansion of the
infestation. The use of herbicides is a necessary early step to restore
healthy habitats on the refuge because of the severity of infestations.
This plan also recognizes the need to rotate herbicides to prevent
chemical resistance from developing. After a few years of effective
herbicide treatments, the use of herbicides will be reduced sharply as
invasives are eliminated or controlled, scouting reveals new
infestations at an early stage, revised farming and other cultural
practices minimize the spread of weeds, and range sites are restored.

Treated sites will be monitored to determine the success of treatments,
with the goal of measuring the degree of control or suppression
attained, expressed as the percent the stand was reduced. Management
should be adaptive based on the results of various products, rates and
tank mixes, progressing to employ the treatments that are most effective
in the context of the Maxwell landscape. Rotation of herbicides to
minimize pest plant resistance, using a different product with a
differing mode of action, should be an integral part of the integrated
pest management practices.

Control of grasshopper infestations will be based on the results of
weekly scouting for grasshoppers and monitoring of soil temperatures as
warmer spring conditions arrive. When grasshoppers are detected,
quadrant sampling will begin. Control measures will be based on the
dominant species in an infestation, and on food preference(s) of these
species, with treatment based on action thresholds and the
attractiveness of oat bran bait to that species. Barley, grown as either
a green browse and/or grain crop, will be maximized and barley will be
used as a buffer surrounding other crops.

**Additional Elements for an Effective Control Strategy **

The best management practice for controlling invasive plant infestations
will include the integrated pest management approach elements identified
in the \"preferred alternative\" discussed above. However, for the
Control Strategy to work optimally there are other elements to bring
into the strategy.

Restoration of Grassland Habitat**: **Once the control strategy is
implemented and infestations are reduced, controlled, or eliminated,
preventing re-infestation becomes a primary management concern. A
primary means of invasive plant establishment is to colonize disturbed
sites where good stands of competing native vegetation is lacking or
altogether absent.** **Therefore, disturbed sites that hosted
infestations should be restored by replanting native plants species and
possibly providing irrigation water and/or** **low amounts of
fertilizers, if former organic layers are** **absent. For the most part
at Maxwell, this practice will involve using a range drill (not
currently on hand) to plant native grass mixtures. One important
consideration involving grassland restoration sites where Tordon is used
is that picloram, especially at the higher application rates, has a
residual effect inhibiting both grasses and broadleafs. Only lower
Tordon rates (i.e., 1 pint/acre) should be applied in areas where
grassland restoration is expected to take place within two years.

The Natural Resource Conservation Service (NRCS) can provide
recommendations for appropriate seed mixtures for range, based on the
soil type in the area to be planted. One potential strategy for
restoration would be to convert farm field A, or another location that
could be watered, to a restored native plant stand. The availability of
irrigation could benefit germination and survival, ensuring a vigorous
stand. This stand could then be hayed in alternate strips, timed for
maximum seed production and maturity, with the hay then used to seed
other sites, year after year. If field A is to be used, a new flow meter
must be installed before water can be delivered to ensure native grass
germination and growth.

**Securing Additional Funding: **Maxwell has two RONS projects (projects
included in the National Refuge Operational Needs System) that address
the management of invasive plants, one for farm lands and the other for
range restoration. "Lessons learned" involving RONS project #97005 for
\"Pest Plant Control\", included the need for a biologist. The refuge
received \$20,000 in FY99 under RONS project 97005, to develop a
vegetation map, including exotic infestations, for the refuge CCP.
Ironically, although identification and delineation of exotic plants was
part*** ***of the contract***, none*** of the notorious exotics were
identified on the resulting map. Future projects will need be well
written and implemented properly for the program to succeed. Another
lesson driven home by the vegetative survey field work (and the
resulting map) was that the field work was done at the wrong time of
year when plants were not blooming or actively growing, again pointing
to the need for understanding the biology of the pests on the Refuge. If
the timing is not right, then objectives will not be met.** **With these
lessons in mind, Maxwell NWR will seek additional funding through the
aforementioned county weed workgroup for a National Fish & Wildlife
Foundation Grant to control invasive plants, but a non-Federal match is
a requirement that may prove somewhat difficult for the Colfax County
Weed Taskforce to acquire. In-kind labor will be proposed as a match may
be one partial solution. Logical inclusions in such a grant application
would be funds for outreach materials, native grass seed mix and for a
range drill, the latter needed to plant seed, with a minimum of soil
disturbance that would encourage re-invasion. Funding may also be sought
from other sources, including foundations.

**References Cited**

Bomar, CR; Lockwood, JA; Pomerinke, MA; and French, JD**. ** Multiyear
evaluation of the effects of *Nosema* *locustae* on rangeland
grasshopper density and natural biological controls. Environmental
Entomology, vol 22, no. 2, pp 489-497, 1993

Colorado Natural Areas Program, Colorado State Parks, Colorado
Department of Natural Resources, and Colorado Department of Agriculture.
2000. Creating an Integrated Weed Management Plan: a Handbook for Owners
and Managers of Lands with Natural Values. Caring for the Land Series
Vol. IV. 341 pp.

MeisterPro Publishing Company. 2002. Weed Control Manual 2002.
Willoughby, OH. 578 pp.

Patrick, C. 1998. Grasshoppers and their control. Texas Agricultural
Extension Service, Texas A&M University. Report L-5201. 4 pp.

Sheley, R. L. and J. K. Petroff** **(eds.). 1999. Biology and Management
of Noxious Rangeland Weeds.** **Oregon State University Press,
Corvallis, OR.