Horseback Team Key to Protecting Jackson Hole Backcountry

Dave Hanna managing invasive plants in Jackson Hole, WY.

Dave Hanna managing invasive plants in Jackson Hole, WY.

By CELESTINE DUNCAN. Photos by Dave and Karin Hanna.


Teton County Wyoming lies in the heart of the Yellowstone Ecosystem and is home to some of the most spectacular scenery on Earth. Rugged peaks, high-elevation lakes, meandering rivers, and broad meadows characterize the 2.7 million acres. More than 97 percent of the county is public land, including Grand Teton National Park, Bridger-Teton National Forest, the National Elk Refuge, and about 40 percent of Yellowstone National Park. 

FIGURE 1: Multi-day trips into the Teton and Gros Ventre Wilderness are needed to monitor and treat invasive plants.

FIGURE 1: Multi-day trips into the Teton and Gros Ventre Wilderness are needed to monitor and treat invasive plants.

Each year more than three million tourists come to Teton County for hiking, wildlife viewing, and other recreational opportunities. With high public use and more than 1,270 miles of trails in the county, the opportunity for introduction and spread of invasive plants is high. 

Mark Daluge, Assistant Supervisor for Teton County Weed and Pest District, believes that trails serve as the primary vector for weeds into the backcountry. “Managing these areas is a real challenge due to remoteness, use restrictions, and a short growing season,” Daluge explains. 

Hiking crews historically controlled invasive plants in the backcountry; however, the work was inefficient, exhausting, and treated areas were limited to a half-day hike. Daluge explains, “Crews with backpack sprayers can cover about 2 to 3 miles a day and need to be near a water source. This greatly limits the miles of trails that can be covered in a season.”

Since 2004, contractors with horse-mounted equipment have been hired to monitor and control invasive plants along backcountry trails. The horseback crews are much more efficient and can cover about 13 or more miles of trail per day. They can also carry food, water, and camping supplies for multi-day trips (Figure 1). 

Partners with the Jackson Hole Weed Management Association provide funding for the project (Sidebar 1). The Teton County Weed and Pest District provides herbicide, GIS support, and contract oversight.  Priorities for monitoring and control are established based on risk for invasion, threat to native plant communities, and operating budget.


Dave and Karin Hanna, owners of Hanna Outfitting, have contracted weed management in the backcountry for the past 12 years. “We initially started using the Saddle-light sprayers, but over the years have adapted our equipment to better fit the steep terrain we are working in,” explains Karin Hanna (Figure 2). 

The Hannas switched from the standard 5-gallon canisters to 3-gallon canisters to reduce stress on the animals. Dave custom-builds their panniers to carry the smaller canisters, extra CO2 containers, herbicide concentrate, and supplies for emergency repairs in the field (Figure 3). Water for mixing the spray solution is dipped from streams and filtered before pouring into canisters.

Figure 2 : Karin Hanna and pack mules managing invasive plants along trails in Grand Teton National Park.

Figure 2: Karin Hanna and pack mules managing invasive plants along trails in Grand Teton National Park.

Figure 3:  Dave Hanna treating cheatgrass on steep hillsides in the backcountry.

Figure 3: Dave Hanna treating cheatgrass on steep hillsides in the backcountry.

The Hannas have five mules and four horses that they rotate throughout the summer season. All the stock is tolerant of packs, spray equipment, and most hazards—which include hikers, grizzly bears, and steep terrain. “The mules are more than 7 years old, so they have the maturity to handle stressful situations,” explains Karin. “Our best horses are ones that we introduced to the program when they were just two years old and trailed behind the more experienced animals. Growing up with the program adjusts the horses to the sounds of the spray equipment and demanding situations that occur in a typical work day.”

Over the last five years, the Hannas have inventoried and treated newly invading weeds on 4,723 miles of trail and hillsides, or an average of 945 miles per season. The Hannas track distance and treatment areas with a GPS, storing their data with the weed district. Noxious weeds targeted in the backcountry include spotted knapweed, musk thistle, houndstongue, yellow and Dalmatian toadflax, whitetop, and cheatgrass. Milestone® herbicide  alone at 7 fluid ounces per acre or Opensight® herbicide  at 2.5 ounces of product per acre control the majority of broadleaf weeds along the trail.

The horseback project is key to Teton County’s Early Detection Rapid Response (EDRR) program for areas that are at high risk for invasion. Riders can closely monitor about 150 feet on either side of the trail and can identify more remote satellite infestations with binoculars. That means each year at least 34,360 acres are inventoried and newly invading plants treated within the high-risk corridors. Based on these figures, the annual cost of protecting the backcountry is about $1.50 per acre, excluding herbicide and oversight expenses (Sidebar 2). 

Mark Daluge summarizes his thoughts on the program. “The horseback program is critical in the protection of pristine areas around Jackson Hole. By implementing EDRR in these areas on a consistent yearly basis, we can continue to protect the backcountry. Without this horseback program, we would never be able to treat and inventory the miles of single track trails, and difficult terrain areas would most likely be left untreated.”

For additional information on invasive plant management in the Greater Yellowstone Area:


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