All posts by TCWeed

Reflecting on 2019

It’s been a great year at Teton County Weed and Pest District.  We reflect on 2019 with great pride as we strive to meet our goals and serve the public.  We are very excited to share the progress on our new insectary, K-12 classroom programs, landowner programs and much more! Check out the links below for all that we have accomplished and please let us know how we are doing. 

You can reach us via our Facebook page or by emailing

Happy Holidays to you and yours and here’s to a wonderful, productive and exciting 2020.

Cheatgrass – Help is on the Way!

Following up on a successful treatment of cheatgrass via helicopter in 2017, Teton County Weed and Pest (TCWP) is planning for another, larger scale treatment during the summer of 2020.  

Cheatgrass, which is an invasive winter annual grass has rapidly spread across the west infesting sage-steppe type habitat.  This grass germinates earlier in the season than native perennials, which allows it to get a head start utilizing resources needed by other species.  Cheatgrass invades the bare ground “interspace” in the native system and soon out competes other desirable species, forming a dense mat of litter that is extremely flammable late in the summer.  Fires that raged on local buttes last summer in cheatgrass infested areas have ratcheted up the urgency to quickly tame the cheatgrass expansion in Teton County.

The 2017 pilot project treated around 125 acres on mostly state land on East Gros Ventre Butte, funded by the Wyoming Wildlife and Natural Resources Trust.  The project’s goal was to see how efficient and effective treatment of cheatgrass via helicopter could be on Teton County’s steep southern facing slopes. This project had a research aspect as well.  While most of the hillside was treated using the most common product, Plateau (Imazapic), three plots were set aside to treat with a newer pre-emergent focused chemistry called Esplanade (Indaziflam).  Now, two years after treatment the plots have been analyzed to see which product is performing the best. While both products are performing at an acceptable level, it is believed that with one more growing season, a clear favorite will emerge to be applied on future sites.

Mapping of potential cheatgrass project areas took place during the summer of 2019 in order gather information on the big picture of the Teton County cheatgrass infestation.  Not surprisingly, a lot of cheatgrass was mapped, totaling over 8,000 acres. As suspected, cheatgrass has continued to spread throughout the county on south/southwest facing slopes from the mouth of Hoback Canyon to the southern boundary of Grand Teton National Park.  The cost to treat this much area is more than one funding source can support, so Jackson Hole Weed Management Association members have embarked on a widespread search and application endeavor to leverage resources to address the funding shortfall. Via nearly a dozen sources, it is believed that the $750,000 project sticker price can be supported.  The treatment will most likely take place in mid to late August, after the grass has cured, and before fall germination. Stay tuned for details of this exciting project!  

Potential treatment sites below:

Education Program

By the close of 2019, the TCWP Education Program has completed development of the following 3 classroom education programs:

  • Flowers, Fruits, Seeds & Weeds (2nd grade)
  • Characteristics, Life Cycles, and Management of Insects (3rd grade)
  • Invasive Species in the Greater Yellowstone Ecosystem (5th grade)

During the 2019-2020 school year thus far, these programs have been delivered to 10 different classrooms, reaching 165 students, for 45 hours of instruction time. Total student hours thus far equal 742.5. I already have 6 classrooms on the schedule for the spring semester, so I expect the student hours may double by the end of the school year. 

For comparison purposes, during the 2018-2019 school year total student hours equaled 576. The year before that, student hours were 211.5. The education program is clearly growing.

As the education program grows, I have considered the feasibility of reaching all 2nd, 3rd, and 5th grade classrooms in the District with these programs, as that would be the ideal. There are currently 47 classrooms at these grade levels. I have been able to schedule programs with 18 of these 47 classrooms to date.  

If my goal is to deliver these programs to all 2nd, 3rd, and 5th grade classrooms in the District, that would require 141 classroom visits ranging in length from 60 – 90 minutes each. Given that there are 180 days of student instruction in a typical school year, and assuming I can visit up to two classrooms per day, this goal is possible to achieve. However, working out a schedule that works for all teachers is the challenge. I am currently making efforts to reach out to as many teachers as possible to see how many classrooms I can realistically reach.

In the future, I would like to develop a program to teach Middle School students about Aquatic Invasive Species. I am also envisioning a high school program that involves long-term research on the effectiveness of different invasive plant management strategies.  

In addition to developing classroom programs, I continue delivering programs at annual educational events including the 4th Grade Wildlife Expo and the 7th grade Adopt A Trout field day.

Finally, In November of this year we provided a 7-hour workshop to 23 participants from 9 Wyoming counties and the WGF Dept, to train participants to offer the 5th grade education program we have developed in their respective Districts. I have since worked more closely with 2 of those 9 counties who are planning to implement programs as soon as this January. 

New Declared Species

Each year Teton County Weed and Pest District staff monitors for new species, potential threats, and sleeper species (non-native species that begin to show invasive properties) to determine if they are an active threat to the ecosystem in Teton County. This year TCWP drafted resolutions to add two species, bittersweet nightshade (Solanum dulcamara L.) and garlic mustard (Alliaria petiolata), to the county declared species list. The additions of both species were approved by the Wyoming Weed and Pest Council in November and are awaiting final approval by the Wyoming Department of Agriculture.

Bittersweet nightshade

Bittersweet nightshade is a perennial vine native to Eurasia and was introduced to North America as a medicinal plant. It spreads by both seeds and rhizomes. This species is also called climbing nightshade because of its vining growth habit that allows it to climb up other plants and structures forming dense stands and choking out light. The bright red berries are attractive but also poisonous creating a hazard for pets and children.

In Teton County, bittersweet nightshade can be found in riparian areas and disturbed sites. The highest densities of this species are in town in Jackson along alleyways, in empty lots, and along pathways. Treatment options include pulling young plants when the soil is moist in order to remove as much of the root as possible or chemically treating with glyphosate, 2,4-D or Opensight.

Garlic mustard

Garlic mustard is also a native of Eurasia and was introduced to North America as a medicinal and edible herb. This species is a biennial that produces an average of 600 seeds per plant and exudes allelopathic chemicals forming dense stands that choke out native species.

In Teton County, garlic mustard has been found in two different locations. Because of recent development, TCWP staff hypothesized that seeds were brought in on construction equipment or in fill dirt. Treatment options include hand pulling or chemically treating with Telar.


Landowners and managers face a myriad of issues in invasive species management. Teton County Weed & Pest staff are working with these landowners and managers to assist with decision making and provide guidance for effective long-term management through the following programs:

Land Development Regulations

Preventing the introduction of invasive species can save landowner thousands of dollars and hours of time in management; disturbance, as occurs during construction and development, is the primary means of introducing new invasive species. Since 2017, all new development or additions that require a grading permit must have an invasive species management plan to prevent the introduction and spread of invasive species. As Teton County Planning Department settles into their new hires, TCWP continues to work to streamline the process for creating management plans for each application. By having a management plan in place before and throughout the construction process, landowners can reduce the long-term impact of invasive species on their property.

HOA Wide Management

Once invasive species are present in the landscape, they rapidly and aggressively spread without adhering to human designated boundaries. To help individuals and neighbors create a cohesive management strategy, TCWP is working with several Homeowners Associations (HOAs) to create HOA-wide management plans. HOA-wide management plans allow for comprehensive management of invasive species on a landscape scale. Management at this scale can help alleviate some of the financial burden. It can also assist both HOAs and part-time residents with maintaining properties that are not occupied year-round.  

Trout Friendly Lawns

TCWP has partnered with the Jackson Hole Clean Water Coalition and is helping promote the Trout Friendly Lawns program. This program centers around appropriately utilizing pesticides, fertilizers, irrigation and landscaping materials to protect water quality. Landowners and managers can reduce their inputs by planting native species and buffer strips around water bodies, testing the soil before applying fertilizer, using slow-release fertilizers, using mechanical removal of weeds and invasive species when appropriate, and by spot treating with pesticides when needed. More information on the Trout Friendly Lawns program and the Jackson Hole Clean Water Coalition can be found here:

Early Detection Rapid Response – We are Winning!

The Teton County Weed and Pest District’s (TCWP) Early Detection Rapid Response (EDRR) program has been in place for nearly 20 years.  This program targets species that are rare in our county for treatment efforts and brings awareness to species that are not yet found here but have shown to be highly invasive in neighboring areas.  By identifying potential threats, TCWP can train staff on what to look for so that infestations are found early, when the probability or possibility of eradication is high.  

This season, TCWP staff was successful in locating the first garlic mustard (Alliaria petiolata) plants found in Teton County.  This species native to Europe was most likely brought to the United States for food or medicinal purposes and has fully colonized the eastern and midwestern US.  It is an early season biennial with coarsely toothed leaves and white flowers that spreads via seeds developed in the slender capsules that can measure up to 2.5 inches long.  This species has been approved to be added to the Teton County Declared Species List and will be treated with dedication next summer. 

The EDRR program focuses on priority one and two species which are listed here, as well as whitetop (Lepidium draba).  This year, our Seasonal EDRR Technician was tasked with checking 1813 known locations of which, 935 had no live plant present.  Each season the plant status is recorded and monitored to evaluate effectiveness of timing and treatment. If a location does not have live plants present for five years in a row, it is removed from the yearly list and will only be checked periodically (every 5 years) moving forward.  This season 193 such locations (20.6%) were removed from the yearly database. Of course, every year our dedicated staff helps locate new EDRR plants, which amounted to 127 points (17.1%) being added to the task list this year. In the end, an 8.9% net reduction in EDRR locations was accomplished in 2019.

One specific area has been targeted for EDRR work since the early 2000’s is the Snake River.  The Snake River Project has proven to be a great success over the years. This project, which targets EDRR species, saltcedar (tamarisk) and perennial pepperweed (Lepidium latifolium) in particular, is funded in part by Teton Conservation District and the Wyoming State and Private Forestry grants.  For this project, crews float the Snake River and walk the cobbled islands each summer in search of new infestations of species to be managed using the EDRR technique.  This effort has amounted to the detection of 107 saltcedar and 523 perennial pepperweed infestations thoughout the history of the project. Utilizing the Early Detection Rapid Response tactic, these populations have shrunk to 15 and 142 respective locations that continue to be monitored.  This reduction computes to an 85% success rate in eradicating saltcedar and a 73% success rate eliminating perennial pepperweed. This season, no new saltcedar and three new perennial pepperweed plants were discovered. Moving forward, TCWP is hopeful that Working Dogs for Conservation can be utilized to “sniff out” infestations that have not been detected by our staff, in order to ensure ALL populations are located.  

ArcCollector program for monitoring EDRR species

Without the Early Detection Rapid Response mindset, these high priority species might not get treated with such diligence every year.  Many are prolific seed producers and are extremely adaptable to different habitats. Left unchecked, these non-native species quickly crowd out our native species, reducing biodiversity, decreasing availability of resources for wildlife, increase fire and flooding frequency, and lead to severely altered ecosystems.   In an industry where success stories can be fleeting, the TCWP EDRR program proves that “an ounce of prevention” truly is “worth a pound of cure”.  

JHWMA 20 Years of Partnership

Where has time gone!  The Jackson Hole Weed Management Association (JHWMA) was formed in 1999 when partners signed a Memorandum of Understanding that allowed all to share resources to prevent and manage invasive species across Teton County. Still going strong as the group enters its 3rd decade, it continues cooperation on projects that focus on specific problems and not jurisdictional boundaries. Hundreds of thousands of dollars have been leveraged in grant funds for projects focused on the health of our ecosystem and improving wildlife habitat. The Snake River, Gros Ventre River, Upper Gros Ventre watershed, Bridger-Teton Wilderness Areas, backcountry forest and park lands, and mule deer winter range are just some of the areas in which the group has coordinated.  Many thanks to our partners and here’s to another 20 great years! 

  • Bridger-Teton National Forest
  • Bureau of Land Management
  • Bureau of Reclamation
  • Caribou-Targhee National Forest
  • Fremont County Weed Department, Idaho
  • Friends of Pathways
  • Grand Teton National Park
  • Hanna Outfitting
  • Intermountain Aquatics
  • Jackson Hole Conservation Alliance
  • Jackson Hole Land Trust
  • Jackson Hole Wildlife Foundation
  • Jackson/Teton County Parks & Recreation
  • National Elk Refuge
  • Natural Resource Conservation Service
  • Snake River Fund
  • Teton Conservation District
  • Teton County Weed and Pest District, Wyoming
  • Teton County Weed Department, Idaho
  • Wyoming Dept. of Transportation
  • Wyoming Game and Fish Commission

Gros Ventre River Spray Days

3 days, Dozens of People, Thousands of Acres Protected

Every July, the JHWMA hosts cooperative noxious weed spray days along the Gros Ventre River.  Volunteers come from as far away as Idaho Falls and Casper to team up. The group targets spotted knapweed, Dalmatian toadflax and perennial pepperweed on public lands along the river corridor.  The invasive weeds treated compete with native vegetation, adversely impacting wildlife habitat, and transforming ecosystem function.

The first indication of knapweed on the Gros Ventre River is briefly discussed in minutes from a Weed and Pest District Board meeting in 1974, though the exact location is not mentioned.  In 1999, JHWMA partners decided it was important to begin recording the presence of noxious weeds throughout Teton County. The Gros Ventre River from the Goosewing Ranch area to the confluence with the Snake River was surveyed as part of this effort. At that time, spotted knapweed was only located as far upstream as the Forest/Park boundary. No other infestations were identified upstream (east) of this location. This prompted the beginning of what is now known as the JHWMA’s Annual Gros Ventre River Spray Days project. 

In 2000, crews from Grand Teton National Park, the Bridger Teton National Forest, Teton County Weed and Pest, and the National Elk Refuge began targeting spotted knapweed along the river corridor in the hopes of reducing and containing the infestation and keeping the infestation from spreading further east into the Gros Ventre area and south onto the Elk Refuge.  Despite these efforts, in 2001 spotted knapweed was found between the Forest/Park boundary and Lower Slide Like on the Gros Ventre Road. Then in 2008, it was found in the campground at Lower Slide Lake. This indicates that in addition to traveling downstream, knapweed is also traveling up the road with humans (vehicles, horses, snowmobiles, UTV’s, etc). This movement highlights the importance of public awareness of how we can prevent the spread of invasive species to our favorite recreation areas by following PlayCleanGo ( principles.

Gros Ventre River Spray Days continues to be integral to the protection of wildlife habitat in Grand Teton National Park and the National Elk Refuge. Unfortunately, the spotted knapweed infestation is so extensive that it will never be eradicated. However, with careful planning and targeted treatments, JHWMA partners are containing and reducing the infestation. Annually, crews treat roughly 50-100 acres of invasive species in this 1,200+ acre project area, thanks to grant funding and dedicated funding from agencies. 

Agencies, organizations, and businesses that have assisted with the project over the years include but are not limited to: 

Fremont, Lincoln, Natrona, Park, and Teton County Weed and Pest Districts in Wyoming, Bonneville and Teton County Weed Districts in Idaho, Jackson Hole Fire/EMS, Boreal Property Management, Jackson Hole Property Services, Intermountain Aquatics, the Bridger-Teton, Custer Galatian, and Shoshone National Forests, the National Elk Refuge, Yellowstone and Grand Teton National Parks as well as the National Park Service – Northern Rockies Exotic Plant Management Team.  The Bureau of Land Management, Wyoming Department of State Lands, Jackson Hole Land Trust, Hanna Outfitting, Gros Ventre River Ranch, Jackson Hole Golf and Tennis, Teton Conservation District and the Rocky Mountain Elk Foundation. 

2016 JHWMA Gros Ventre River Spray Days Team
Mosquito Abatement Program

TCWP’s mosquito abatement program encompasses Teton County in its entirety. Our field work starts in mid-April and ends in late August. While not as visible as the roadside weed control crews, the mosquito team members are equally busy, working in wetlands, ponds, and flooded fields.

TCWP’s mosquito program is four-part:

  • Sampling and Mapping: We field sample and map mosquito habitat for the presence of larvae. This information is entered into our GIS database and is used for future mosquito management decisions. 
  • Larvicide: Larvicides are environmentally safe products that kill mosquito larvae. These products have, as an active ingredient, bti, which is a naturally occurring soil bacteria. Bti is only toxic to mosquitos and is rendered inert by the sunlight and air in 48 hours. Larvicide applications typically commence when mosquito larvae are detected at sampling sites and continue until the larvae are eliminated. Historically, TCWPs’ trained crews have manually applied larvicides, but our new drone technology is showing promise as a replacement for this laborious task.  
  • Trapping and Adulticide: Specialized traps are used by TCWP staff to determine adult mosquito populations and specie composition. Samples of the captured adults are collected for analysis and testing for the presence of West Nile Virus. Adulticide (fogging) treatments are initiated when trap catch numbers reach pre-determined threshold levels.

Outreach: TCWP strives to increase public awareness of all our programs. Mosquito abatement outreach involves one-on-one property owner contacts and service call visits. We very much appreciate the on- going support and cooperation displayed by Teton County residents.

Seasonals and Weed Treatments

This year we were able to hire 17 seasonal employees. 9 of them were returning from previous years, and 8 were new hires. They all had a variety of different backgrounds and came from all across the country. With their help, hard work, and dedication to the job, we were able to have a very successful summer season. We were able to complete all of our project areas and contracts, and some areas we were able to get to more than once which should increase our level of control in those areas.

Overall, our crews were able to treat about 222 acres of invasive weeds throughout Teton County and the Snake River Canyon. Our 2 person crews working on Bridger Teton National Forest (BTNF) and National Elk Refuge (NER) lands were each able to treat around 20 acres. The BTNF team covered a large area from up North on Togwotee pass all the way down to the Sheep Gulch boat ramp. They mostly concentrated on trail heads, forest service roads, and boat ramps. The NER crew mostly focused on getting to known points of high priority species, as well as treating areas throughout the NER where there were infestations of other species such as musk and Canada thistle.

The rest of our crew spent a lot of time on state highway properties and rights of way (63 acres), on Grand Teton National Park rights of way (24 acres), county roads, levees, and parcels ( 35 acres), BLM lands (19 acres) Wyoming Game and Fish properties (12.5 acres) as well as the town of Jackson and parks and rec properties (13.5 acres). We also had one of our seasonals go around throughout the county to known points of our higher priority species and recording and treating what he was able to find there. Through his efforts, he was able to treat about 6.5 acres of those high priority species. 

We wouldn’t be able to get our work done without our seasonal crews. They spend a lot of time on the side of the road in the heat, climbing up and down steep hillsides in pursuit of invasive weeds. We rely on their hard work and appreciate every bit of it. 

The Lab Insectary

This year, our mosquito lab manager Mikenna Smith built a mosquito insectary as an extension of the lab. She toured the Salt Lake City Mosquito Abatement District’s (SLCMAD) lab and their insectary to learn how to build one here at TCWP. Eggs of two insecticide-susceptible colonies were obtained from SLCMAD (Aedes sierrensis and Culex pipiens) and a third colony was established using a wild-caught species (Culiseta inornata). The Cs. inornata colony will be tested for insecticide-susceptibility in 2020. The reasons for building an insectary and maintaining mosquito colonies year-round are multi-faceted. By having an insectary and insecticide-susceptible colonies, the District is now able to perform all types of insecticide resistance testing. This includes calibration of insecticide mortality curves with susceptible strains and rearing of wild-caught samples in a controlled environment to perform the CDC bottle bioassay. Comparing mortality curves of local populations to insecticide-susceptible colonies allows TCWP to monitor local populations for resistance to insecticides. By rearing wild-caught samples up in the insectary, age & nutritional status can be controlled before the tests are performed.  Controlling for potential confounding factors helps provide quality data. Additionally, the mosquito colonies can be used for insecticide-resistance validation and adulticide efficacy testing in the field. Insecticide resistance monitoring and adulticide efficacy testing are encouraged by the CDC & AMCA to be performed at the District level. The National Association of County and City Health Officials has also stated that insecticide resistance monitoring is where the greatest gap in competency lies for mosquito abatement districts in the United States. TCWP is now able to meet all such expectations in our integrated mosquito management program (IMM).

The construction and maintenance of the insectary not only adds to the District’s IMM program by providing the ability to perform all resistance tests, but the colonies were also successfully used in the classroom education programs. Mikenna worked closely this year with our education coordinator Meta Dittmer to provide mosquito eggs for the third-grade life cycle science lessons. The students raised the mosquitoes from eggs to adults and journaled about the life cycle of their “mystery insect.” It was important for the lab to be able to provide eggs of local species in the education program over using non-native species. Overall, the construction of the insectary and provision of eggs for education was a great success and will continue to be a valuable resource for the District’s IMM program. 

Unmanned Aircraft Systems – Into the Unknown

In the spring of 2018, the Teton County Weed and Pest District jumped into the world of Unmanned Aircraft Systems (Drones) headfirst.  After years of research and discussions, the staff and board concluded that the technology and price point was finally at the desired levels to purchase a drone capable of spraying pesticides and begin to integrate it into treatment operations.  

The unit that was purchased is called the Agras MG1S and is manufactured by DJI.  The aircraft has eight propellers, a 2.6 gallon tank for liquids, four spray nozzles spraying up to 4.5 gallons per acre, obstacle avoidance radar, has a max speed of 33.5 miles per hour (treatment max speed of 15.6 mph), and is fully programable to treat areas autonomously.  Flight time on each battery is around 10-12 minutes, which nearly matches the time it takes to “spray out” the tank. This tool will allow two staff members to treat three to four acres per hour, without the backbreaking weight of a spray backpack.  

Staff managed to squeeze in enough time during the initial summer to get the proper certifications/licenses, and to learn the ins and outs of drone operations.  The first treatments took place during the fall of 2018, on flat cheatgrass plots to test the aircrafts ability to spray areas effectively, and the staff’s ability to plan treatment areas and execute the missions.  Building upon the success of the previous year, further tests were planned for the upcoming season. First, it was decided to utilize the aircraft to treat for mosquito larvae in flooded fields. These missions seemed easy enough, being flat and mostly uniform.  Upon a few trials, staff learned that the target treatment areas needed to be easily accessible by truck in order to limit drone travel time to and from the treatment block and the staging area must be dry and away from potential obstacles. With the successful treatment in these areas, sites that meet these requirements and frequently need larval treatment will be mapped ahead of time in order to maximize treatment time.  The next potential use for the aircraft that was considered were steep hillsides that which are infested with spotted knapweed (Centaurea maculosa) and cheatgrass (Bromus tectorum).  Following a few learning experiences, it was determined that by utilizing the “terrain follow” setting on the drone, treatment of patches of these species on steep hillsides could be accomplished.  While effectiveness of treatment in these areas will not be able to be evaluated until this spring, TCWP staff are optimistic that this tool can be used in these instances throughout the valley.  

While technology commonly presents challenges, TCWP staff are eagerly looking ahead to next year, where widespread drone operations will be planned for mosquito control and weed treatments where species densities are high, and/or terrain is steep and hard to treat on foot.

Welcome New Board Member – Lucas Turner

2019 brought a change to the Moran representation on our Board.  We welcomed Lucas Turner to the Board in January. Lucas brings a wide range of expertise, having grown up on and now working at the Triangle X Ranch. His experience on the Ranch brings the ideal mix of knowledge related to ranching, livestock, hay production, invasive species management, staff oversight and program management.  Welcome Lucas! 

Weed of the Month: Canada Thistle

Can YOU outsmart the smartest weed in the West?

Canada thistle may be the cleverest weed in the West

Canada Thistle, Cirsium arvense, may be the cleverest weed West of the Mississippi. It boasts a long list of weedy characteristics, including:

  • Perennial growth habit
  • Ability to reproduce from creeping rhizomes (underground stems that creep out laterally in all directions)
  • An abundance of wind-dispersed seeds that are also long-lived (up to 22 years!)
  • Spiny leaves that are avoided by wildlife and most livestock   
  • Tolerant of a wide range of soil conditions
  • And worst of all, roots that penetrate anywhere from 6 – 15 feet deep, sequestering nutrients that allow Canada Thistle to recover from any attempts to control it at the surface.

To outsmart a weed like this, one must get to know it intimately and discover and exploit its weakness.

So, let’s get to know Canada thistle!

This first thing to know is that it is NOT from Canada. This thistle is native to the Mediterranean regions of Europe and North Africa. It was accidentally introduced to Canada in a shipment of contaminated grain in the 1600s. It spread down the east coast of the US and was first discovered in the Rocky Mountain west in the 1800s. It is currently the most widespread of all thistle species. 

Canada thistle is native to the Mediterranean region, but is now widespread in North America

The next thing to know is that Canada thistle is not like any other thistle you have encountered. Unlike Musk, Bull, Scotch, and Plumeless thistles, which all emerge from a stout taproot as an individual plant, Canada thistle produces extensive patches with hundreds or thousands of tiny stems that are genetically identical and arise from a shared root system. Therefore, pulling one “plant” in a patch of Canada thistle is as effective as picking a single leaf from a tree hoping to kill the tree – NOT effective at all!

Canada thistle has a creeping perennial growth habit which means this entire patch is probably one genetic individual, much like a clone of Aspen trees

Canada thistle also differs from the other thistles in being dioecious. This means that each plant (or patch in this case) is either male or female and bears flowers that will produce either pollen or seeds. A Canada thistle patch that is female must be pollinated by a patch that is male in order to produce viable seed and having male and female plants separated in space may reduce the probability of viable seed production. However, when male and female plants do find each other, one flowering shoot can produce 1,000-1,500 seeds that can lay dormant in the soil for up to 22 years. So, it is still worthwhile to cut and bag any seed heads you encounter. 

Canada thistle seeds can lay dormant in the soil for up to 22 years awaiting the right conditions for germination

A large patch of Canada thistle is essentially one clonal plant, either male or female, and to kill it, one must kill ALL of it. The challenge is finding a way to kill the extensive underground root system that penetrates to a depth of up to 15 feet and extends to a breadth of at least that. The only way to succeed in eliminating Canada thistle is to injure and exhaust this root system, and do so repeatedly, treating for multiple seasons and multiple times within a season. 

To eliminate Canada thistle, you must be able to kill its extensive root system. This is a challenge.

If you want to outsmart this weed, follow these steps:

  • Spring treatment: All winter, Canada thistle lays dormant under the ground, subsisting on the nutrients stored in its roots and rhizomes. When the snow melts in spring, it will use that precious stored energy to push a flush of leaves out of the ground, which will start out as a patch of spiny rosettes.
A spring flush of Canada thistle rosettes

The rosettes will leaf out and grow taller and eventually produce buds and flowers for reproduction. Once the buds emerge, the energy stored in the root system is at a seasonal low. Now is the time to severely weaken the root system by abruptly removing all the surface vegetation, either by mowing it close to the ground or by applying an herbicide like Glyphosate, Speedzone, or Milestone to the leaves. This will force the thistle to further deplete its nutrient reserves in order to replace the vegetation it lost. 

The Spring treatment of Canada thistle should be applied at the bud stage of growth
  • Fall Treatment:   After the spring treatment, the weakened plant will take some time to recover. But recover, it will. In the late summer/early fall, in preparation for winter dormancy, it will muster the remaining energy reserves from its roots and push up another flush of leaves. The purpose of these leaves is to vigorously photosynthesize and transport all the sugars produced down into the root system so it can survive the winter and have energy for a flush of leaves in the spring. Now is the BEST time to treat with an herbicide because the chemical will inadvertently be transported down to the root system, along with the photosynthates. The herbicide recommended by TCWP for fall treatment in non-lawn areas is Milestone. If you are treating the thistle in a turf grass lawn you will need to use a lawn-approved herbicide like Speedzone, Tri-Mec, or Mecamine-D. You will want to treat before a killing frost, but after the first frost to have the best chance of getting the herbicide down to the evasive root system. 
    1. NOTE: If the plant was able to produce healthy regrowth soon after the spring treatment, plan to cut it back 3-5 weeks before applying the fall Milestone treatment. This will encourage active growth in the plant and produce clean new leaves that lack the waxy cuticle present on mature leaves, allowing the herbicide to penetrate the leaves and circulate throughout the plant more easily, increasing its effectiveness. Whenever using herbicide, refrain from cutting or mowing treated vegetation until after the herbicide has had a chance to work. This could be as long as 2-3 weeks.
  • Repeat: This procedure should be repeated for at least 3 years. 
  • Replant: Plant new vegetation to compete with the Canada thistle and any other weeds that may try to get established as soon as possible after herbicide treatments begin to take effect. Check the label of the herbicide you used to see how long you must wait before replanting an area that was treated. For Milestone it can be up to 18 months.

These four steps are the most effective means of eliminating Canada thistle from your property. This requires patience, vigilance and use of chemical herbicide.

If herbicide must be avoided, it may be possible to exhaust the root system of Canada thistle using a combination of mechanical methods such as mowing, digging, and grazing. However, this process will require A LOT of patience, diligence, and time. 

For more information on Canada thistle treatment see these links:

Weed of the Month: Spotted Knapweed

Spotted knapweed (Centaurea maculosa) is blooming and suddenly seems to be everywhere.  It’s grey-green wiry foliage help it blend into surrounding vegetation until its pink flowers appear. Then suddenly we see the vast extent of its infestation.

Spotted knapweed is in the aster family, along with many other noxious weeds including Oxeye Daisy, Scentless Chamomile, and all the thistles. The pink flowers of spotted knapweed are reminiscent of Canada Thistle, but knapweed lacks the spiny leaves of thistles. Spotted knapweed can also be distinguished by the black tips on the bracts that make its involucre appear “spotted”(and give the plant its common name).

For those who are not botanists, the involucre is the whorl of bracts (scale-like structures) surrounding the inflorescence of flowers in the aster family.  

Like many noxious weeds in our area, spotted knapweed is native to Eurasia where the climate is similar enough to the rocky mountain west that it can thrive here. In its homeland, it has many limiting factors that keep it from being invasive. These include competition from other plants and herbivores that like to feed on it. However, such limiting factors are not present in the Greater Yellowstone Ecosystem, which allows the spotted knapweed to reproduce and spread, apparently unimpeded.

This creates a challenge for our native wildlife. Spotted knapweed can provide reasonable nutritional value to ungulates when it is young and green. But once it produces flowers, a chemical in its leaves make it unpalatable. Over the course of a year, the nutritional value of spotted knapweed to grazing ungulates is very poor. The knapweed also has the ability to reduce competition from surrounding vegetation by releasing a chemical from its roots that inhibits germination of other plants. So eventually, spotted knapweed can replace the native grasses and forbs that wildlife rely on with a forage of much lower quality.

Elk eat knapweed unwillingly after it has replaced more nutritionally valuable native grasses
Photo credit: Casper Star Tribune

If you have spotted knapweed in your yard, you may notice that it will eventually replace everything else growing in your yard and make your soil less hospitable to other plants, decreasing your property value.

So what can you do if you find spotted knapweed growing on your property?

  1. You can dig it up if you get the entire root out
  2. You can treat it with an herbicide like Milestone, available at Teton County Weed and Pest.
Spraying spotted knapweed along the Gros Ventre River

If you are not sure that what you have is spotted knapweed, click here and submit a Weed ID service request with an uploaded photo of your weed and we will confirm its identity. You can also bring a sample to our office.

PlayCleanGo Partner: Scenic Safaris & Mad River Trips

Teton County Weed and Pest District wants to applaud the efforts of our PlayCleanGo partners in the valley. PlayCleanGo: Stop Invasive Species In Your Tracks® is a nationwide outreach campaign made up of passionate outdoor enthusiasts (individuals and businesses) working tirelessly to protect our natural resources.

We are proud to feature Scenic Safaris & Mad River Trips for our first PCG partnership and the efforts they take to practice these principles in their wildlife adventure tours and rafting trips in the summer.

1. Why did you decide to become a PlayCleanGo partner? 
From a company’s perspective though keeping a wrap on potential invasive species is important to us. If we do not manage the potential then the problem will manage itself which is the most undesirable for everyone from company, employee, local enthusiasts and our guests. We are just doing a component with keeping our machines cleaned thoroughly after each use.

2. How do you advocate for PlayCleanGo practices through your company? 
We could do a better job talking about it to our employees for sure. Our belief is in our daily practice of operations which allows us to know its being done very thoroughly. 

3. What invasive species do people need to be especially aware of in Jackson? 
Unfortunately we have noxious weeds as well as the aquatic invasive in the valley. We have more potential threats in the region (ie the zebra mussel.)  We focus on both terrestrial and aquatic inspections and cleaning, for noxious weeds we wash all overland vehicles after each use, especially when traveling off the tarmac.  Our rafting operation gets inspected regularly by our staff as well as the AIS staff where we register our boats as every other boat owner to comply with those regulations.

4. What do you think is the best way to spread awareness to friends and family members about the detriment invasive species pose to society?
My opinion is that they must be able to see visually what the problem looks like and have the compassion to feel that the effort is warranted to where they themselves want to take action. I feel like this is a tall task. 

5. Do you share PlayCleanGo practices with visitors to Jackson and GTNP? If yes, how do you do that? 
Something that we could do a better job with as a company. We do have educated staff that know of these issues in our community and even deal with them at their homes. We do not have our staff do a presentation on this with clients at the moment, but I know that it is a topic of conversation with customers because it was a topic discussed often when I guided day to day. 

Considering becoming a PlayCleanGo Partner? 

What if every outdoor enthusiast were provided with the tools to Stop Invasive Species in their Tracks? Could we stop them? We think so. We have 550+ partner organizations already, representing thousands of individuals who believe we can do it too.

Join forces with like-minded individuals, organizations, and businesses across North America. Become a PlayCleanGo partner now!

Doing Your Part Giveaway

Teton County Weed & Pest District is excited to be holding the “Doing Your Part Giveaway” to promote PlayCleanGo practices throughout Teton County this summer season.

Please share your photos/videos of you giving invasives the brush off whether you’re biking, hiking, horseback riding, ATV adventuring and more. Follow us on Instagram and use the hashtag #doingmypart #PlayCleanGo and mention us to enter.

You could win one of the following:

PlayCleanGo boot brush

PlayCleanGo reusable tote bag

PlayCleanGo water bottle


1. Following us on Facebook or Instagram.
2. Share a photo/video and mention us and tag #doingmypart and #PlayCleanGo

Each method is a new entry into the giveaway. 
Winners will be announced mid-August.

What is PlayCleanGo?

This is the initiative to stop invasive species in their tracks. You can help participate by REMOVING plants, animals, & mud from boots, gear, pets & vehicles, CLEANING your gear before entering & leaving a recreation site, STAYING on designated roads & trails, and USING CERTIFIED or local firewood & hay.

Partially funded by the USDA Forest Service, the Minnesota Department of Natural Resources launched the outreach campaign PlayCleanGo: Stop Invasives Species in your Tracks in 2012. The campaign has since expanded to include partner organizations across North America. The campaign has expanded since in large part due to the work of the North American Invasive Species Management Association (NAIMA) who adopted PlayCleanGo in 2015. The campaign goal is to protect valuable natural resources and encourage folks to enjoy the outdoors. Community based social marketing has helped build brand recognition and the objective is to slow (and where possible stop) the spread of invasive species by changing public and worker behaviors at risk of spreading harmful pests living on land or in water. PlayCleanGo promotes awareness, understanding, and cooperation by providing a clear call to action to be informed, attentive, and accountable for stopping the spread of all invasive species.

20th Annual Gros Ventre River Spray Days 2019

Join the Jackson Hole Weed Management Association (JHWMA) for Gros Ventre River Spray Days July 16 – 18, 2019.

Partners in the JHWMA will team up to treat spotted knapweed, houndstongue, and Dalmatian toadflax as well as other invasive plants, which compete with native vegetation and adversely impact wildlife habitat and ecosystem function. This multi-year project has been taking place for over 15 years.  The project area for this event is the Gros Ventre River corridor encompassing the National Elk Refuge, Grand Teton National Park and other public and private lands to the confluence of the Snake River. This project is being organized by Grand Teton National Park, Bridger-Teton National Forest and Teton County Weed & Pest District (TCWP).

JHWMA - Backcountry Horseback Spraying - Man on Horseback in front of Tetons image

The first indication of knapweed on the Gros Ventre River is briefly discussed in minutes from a Weed and Pest District Board meeting in 1974, though the exact location is not mentioned.  In 1999, JHWMA partners decided it was important to begin recording the presence of noxious weeds throughout Teton County. The Gros Ventre River from the Goosewing Ranch area to the confluence with the Snake River was surveyed as part of this effort. At that time, spotted knapweed was only located as far upstream as the Forest/Park boundary. No other infestations were identified upstream (east) of this location. This prompted the beginning of what is now known as the JHWMA’s Annual Gros Ventre River Spray Days project.

In 2000, crews from Grand Teton National Park, the Bridger Teton National Forest, Teton County Weed and Pest, and the National Elk Refuge began targeting spotted knapweed along the river corridor in the hopes of reducing and containing the infestation and keeping the infestation from spreading further east into the Gros Ventre area.  Despite these efforts, in 2001 spotted knapweed was found between the Forest/Park boundary and Lower Slide Like on the Gros Ventre Road. Then in 2008, it was found in the campground at Lower Slide Lake. This indicates that in addition to traveling downstream, knapweed is also traveling up the road with humans (vehicles, horses, snowmobiles, UTV’s, etc).  This movement highlights the importance of public awareness of how we can prevent the spread of invasive species to our favorite recreation areas by following PlayCleanGo ( principles.

Gros Ventre River Spray Days continues to be integral to the protection of wildlife habitat in Grand Teton National Park and the National Elk Refuge. The JHWMA Spray Days event is unique in that it pulls together groups from across western Wyoming.  “The goal is to contain and reduce the spotted knapweed infestation that is thought to have started on the Gros Ventre River in the 1970’s”, stated Erika Edmiston, Supervisor at TCWP. “Without this amazing group coming together for this team effort, we would be losing critical wildlife habitat to these invaders”. Unfortunately, the spotted knapweed infestation is so extensive in this corridor that it will never be eradicated. However, with careful planning and targeted treatments, JHWMA partners are containing and reducing the infestation. Annually, crews treat roughly 50-100 acres of invasive species in this 1,200+ acre project area, thanks to grant funding and dedicated funding from agencies.

“A lot of really great people have come together over the years to make progress on some awfully bad plants which negatively transform ecosystem function in wildlife habitat and an important elk migration area.” said Travis Ziehl, Jackson Hole Property Services.

Agencies, organizations, and businesses that have assisted with the project over the years include but are not limited to:

Fremont, Lincoln, Natrona, Park, and Teton County Weed and Pest Districts in Wyoming, Bonneville and Teton County Weed Districts in Idaho, Jackson Hole Fire/EMS, Boreal Property Management, Jackson Hole Property Services, Intermountain Aquatics, the Bridger-Teton, Custer Galatian, and Shoshone National Forests, the National Elk Refuge, Yellowstone and Grand Teton National Parks as well as the National Park Service – Northern Rockies Exotic Plant Management Team.  The Bureau of Land Management, Wyoming Department of State Lands, Jackson Hole Land Trust, Hanna Outfitting, Gros Ventre River Ranch, Jackson Hole Golf and Tennis, Teton Conservation District and the Rocky Mountain Elk Foundation.

The JHWMA was formed in 1998 to establish common long and short-term management policies, goals, and objectives necessary for cooperatively managing and funding noxious weed activities across all jurisdictional boundaries. 

We would like to thank the Teton Conservation District (TCD) and the JHWMA for their contributions in making this event a success. To learn more about the JHWMA  please visit

New Teton County Weed & Pest District’s Logo

Teton County Weed & Pest District has had their logo for 5 years now and they were looking to a reboot their branding approach. Keeping their mark recognizable was important to them and maintaining the acronym TCWP was important. They were open to a new modern approach. Since the public were starting to relate TCWP’s brand it was imperative to subtle evolve the brand rather than making a radical change.

A little TCWP History

TCWP was established by the Wyoming State Legislature in 1973, consists of a locally appointed government board charged with implementing and pursuing an effective program for the control of designated and declared weeds and pests.

Read more history on TCWP .

Old TCWP logo

The old logo’s TCWP letters were getting lost among the mountains and the general consensus was for the new logo to be easy to recognize from near or far.

The earthy greens were chosen to evoke TCWP’s stewardship of our cherished lands of Teton County. The role of TCWP could be characterized as guardians of Wyoming’s rich ecosystem and this logo was set to evoke a badge of that responsibility.

New TCWP logo – light green
New TCWP – one-color (dark green)
New TCWP logo – dark green
New TCWP – one-color (light green)

Earthy greens and a warm grey

Nevis Bold
Sanchez Regular

Logo design by Gliffen Designs

Weed of the Month: Oxeye Daisy

Oxeye daisy (Leucanthium vulgare) is the dainty white flower that you see blanketing open fields in and around Wilson, giving the impression of snow in summer. 

Although a field of daisies may seem preferable to a field of spiny thistles, or bur-covered houndstongue plants, the impacts on native plant communities and the wildlife that depend on them are the same. 

The 50-ish invasive plants we are mandated to control in Teton County are so named because they don’t just colonize disturbed areas, they INVADE established native plant communities and displace native plants. The characteristics that allow oxeye daisy to invade include the ability to spread through underground rhizomes, a lack of palatability to wildlife and cattle, the ability to tolerate a wide range of soil conditions, and freedom from the predators and pathogens found in its native Eurasia.

Oxeye daisy belongs to a cohort of invasive plants that are often considered too pretty to be a problem. Along with  Dame’s Rocket, Dalmatian toadflax, and others, oxeye daisy is at risk of not being treated due to its perceived beauty and the fact that it is so easy to cultivate. 

Dames Rocket and Dalmatian toadflax are invasive plants that people hesitate to eradicate because of they are pretty AND very easy to cultivate 

But be warned, once oxeye has flowered and gone to seed on your property, you will have daisies coming up for many years to come. Once you start treating them, it will take at least 6 additional years to exhaust the seedbank. One study found oxeye daisy seeds to be viable in the seedbank for 39 years! So the sooner you begin treatment, the better.

Oxeye Daisy Treatment options include:

  1. Dig out entire patches, removing all rhizomes – expect to dig at least 6 inches down to get all rhizomes out.
  2. Spray with an herbicide like Opensight, which is available at TCWP. Repeat treatments in spring and fall each year until the seedbank is exhausted.

Finally, if you really want daisies in your yard, consider planting Shasta daisy. Like oxeye daisy, it is easy to grow, but it is not invasive. Here are some photos to help you differentiate these two daisies:

Can you tell which is which?

Mosquito Season Yet Again.. 2019

With the onset of the summer and its warmer days and longer nights comes mosquitoes. It may seem that their bite may just be a mere annoyance but it can be much more severe than that. Mosquito bites can spread diseases like West Nile Virus and Zika. Mosquito-borne diseases do not only affect humans – they also kill countless birds, reptiles, animals and endangered species each year. Joseph Conlon, AMCA Technical Advisor stated on the subject, “We are continually importing the diseases they carry. We must be prepared to prevent their spread throughout our public health landscape – and this requires safe, effective, sustained mosquito control and awareness in our community.”

National Mosquito Control Awareness Week – June 23-29

June 23 – 29 is “National Mosquito Control Awareness Week” by the American Mosquito Control Association (AMCA) to help spread public awareness about the importance of mosquito management practices. As part of “National Mosquito Control Awareness Week”, Teton County Weed & Pest District would like to share their top abatement priorities for mosquitoes, which are as follows:

  • Vector control for West Nile virus prevention
  • Bio-rational approach to vector control – utilize larval surveillance and treatment as primary means of control to reduce off target impacts. BTI larval treatment is a selective pesticide.
  • Survey and trap adult mosquitoes to determine need for Ultra Low Volume (ULV) fogging.
  • Larval control is the most efficient way to reduce mosquito abundance
  • Encourage a reduction in man-made sources of mosquito breeding habitat

Though one of the major banes of summer that seem inevitable, there are still measures you can take to ensure you and your loved ones have an enjoyable season. What are a few things that landowners and the public can do? You can help identify and report mosquito habitat, help us fill in the permission gaps for surveillance and treatment, dispose of any unused tires on your lot, drill holes in the bottom of recycling containers, clear roof gutters of debris, clean pet water dishes regularly, check and empty children’s toys, repair leaky outdoor fauces, and change the water in bird baths at least once a week, encouraging neighbors to take part in the same preventative measures, and make sure to always practice the 5 D’s of mosquito prevention below:

5 D’s of Mosquito Prevention

  1. DUMP – By periodically dumping standing water you can prevent mosquitoes from growing into adults that feed on you
  2. DRAIN – Regularly draining standing water sources like pet water dishes, water troughs and kiddie pools. Reduce mosquito breeding habitat by not allowing water to stand for long periods of time.
  3. DRESS – Dressing for outdoor activities by wearing long pants and long sleeve shirts made of lighter material like linen are ideal for hot summer months. Consider hats with mosquito netting.
  4. DEET – Use an insect repellant that lists DEET or alternatively lemon eucalyptus oil to prevent mosquito bites. DEET is proven to be the most effective mosquito repellant.
  5. DUSK/DAWN – Mosquitoes are most active during the early morning and evening hours. Try to stay indoors during these time periods. If that’s not possible be sure to dress to prevent bites and use a DEET repellant.

With a few pre-meditated measures, you can help ensure an enjoyable summer, free from the worries and annoyances of mosquitoes around every corner. Take the time to protect you, your family, and community from the grievances of mosquito pests this summer season. Follow Teton County Weed and Pest’s Facebook and Instagram accounts to learn more preventative measures you can take to control mosquitoes throughout the summer season.

Weed of the Month: Houndstongue & Black Henbane

Some of the first noxious weeds that bloom every spring are Black Henbane and Houndstongue. Both are easy to recognize once they flower.

The houndstongue produces deep magenta-colored, five-petaled flowers along wiry stalks. Each flower will become a cluster of four burs that carry the plant’s seeds and will stick to passers-by like Velcro.

Black Henbane has foul-smelling whitish flowers with purple centers. Once pollinated, its flowers produce pineapple-shaped fruits packed with small black seeds.

Both of these plants are biennial- meaning they live for two years – and if you are seeing them in flower, this is the last year of their life. Before they die, they have one wish – to reproduce! They have until fall to produce as many seeds as they can to assure that their progency will live on for many generations. If they get their wish, we can expect a large crop of these weeds to pop up each spring for many years to come.

But since they are biennial, we have some choice in the matter. Here are our options:

  1. Find flowering adults and dig them out! They have a fairly deep taproot, but if you can dig the plant out below the root crown, it will not come back. Since both of these plants have toxins in their leaves, be sure to use gloves when pulling them out.
  2. Spray flowering adults with herbicide! Visit us at TCWP to find the right herbicide for your situation. Note that once biennial plants have gone to seed it doesn’t make sense to spray them because their seeds will still spread and the plant is at the end of its life cycle anyway. If they are in seed, pull them.
  3. Learn to recognize the plants in their first year – when they are NOT flowering – and spray them with herbicide. This is the most efficient way to control these biennial weeds. See below for identification tips.

Houndstongue looks like a cluster of long, hairy, tongue-shaped leaves with pointy tips. It can be confused with native arrowleaf balsamroot at this stage, as that plant also produces a simple cluster of leaves in its first year and those leaves are a similar shade of green. But look closely at the bases of the leaves and you will notice that balsamroot has a distinctive spade-shaped base while houndstongue leaves simply taper to a point at their base.

Whether the Houndstongue is in its first or second year, it can be pulled out by hand if the soil permits. If chopped out below the root crown, it rarely grows back. If the infestation is too large to hand-pull, purchase herbicide at TCWP and use a surfactant to be sure the herbicide permeates the hairy leaves.

Black Henbane resembles a head of cabbage in its first year. But you wouldn’t want to mistake it for an edible plant! All parts of this plant are very poinonous. If you learn to recognize it in its first year, you can chop it out below the root crown or spray it with a TCWP-approved herbicide.

Whichever option you choose, make sure you get rid of these plants before they go to seed and remember to PlayCleanGo so you don’t spread their seeds into uninfested areas.