People & Place
  • Noxious Weeds Montana

Concentrated in the west but scattered across all of Montana, a war is being waged against weeds. It’s not a small battle against a few dandelions here and there. It’s an all out attack on noxious weeds, which, if allowed to spread, can and will consume entire pastures and hillsides, displacing native grasses and leaving livestock and wildlife stranded without food.

Weeds may look pretty to some. With yellow, pink and purple flowers, weeds can give a splash of color to an otherwise monochromatic field of grass. Yet to the educated eye, weeds such as spotted knapweed and leafy spurge are anything but a welcome sight. They threaten the livelihoods of ranchers, outfitters and guides. Cows don’t eat them. Deer and elk rarely do. As the weeds spread throughout public and private land, they displace the native grasses on which those critters feed.

To contain the weeds a patchwork of approaches is tried, ranging from herbicides to biological controls such as sheep and beetles that are natural predators of knapweed. But noxious weeds may have finally met their match in southwestern Montana. With the aid of some modern technology developed by AquilaVision Inc of Missoula, noxious weeds are in for one heck of a counter-offensive.

Madison County is a sportsman’s dream. The deep, cool waters of the Madison River are a home for browns and rainbows, while the surrounding peaks of the Lee Metcalf Wilderness and the Gravelly Range provide a stomping ground for hunters looking for elk, deer, moose and bear. It’s a place with plenty of space between neighbors, too—Madison County averages only two people per square mile.

With so much wide-open space and so many sportsmen visiting the area, Madison County sits on the edge of where the battle over noxious weeds needs to be won, says Dave Burch, Montana’s Noxious Weed Coordinator. It’s the starting point for weeds going east and west in Montana. Noxious weeds already present in Idaho, such as yellow starthistle, could be introduced into Montana easily if no action is taken to prevent the spread. As more people visit, more people fall in love with the area and decide to move in. What some newcomers don’t realize is that when the ground is cleared for their new home, noxious weeds can easily establish themselves in the disturbed soil. And it only takes one seed to turn prime grassland into a monoculture of weeds.

“With new landowners, we try to identify them and communicate with them about weeds,” says Margie Edsall, Madison County Weed District Coordinator. “We try to do as much as we can to educate them.” Part of that education comes in the form of citizen groups like the Madison Valley Ranchlands Group. The group teams up with state and federal agencies, as well as non-profits like the Nature Conservancy, to get the word out to landowners about noxious weeds.

Spotted knapweed, easily the valley’s most widespread noxious weed, is one ornery foreign contender. It grows one to three feet tall and its flower is a pretty pink-purple. The jury is still out regarding how the weed got here, but some researchers believe immigrants from the Ukraine intentionally planted it in Ravalli County in the Bitterroot Valley around 1920. Knapweed produces some seriously sweet honey, and the immigrants may have been looking for a taste of home. Only three years after its arrival, it was reported to have established itself over the Continental Divide in Bozeman. Because knapweed travels by anything that is willing to give it a lift, it sometimes hitches a ride to new home sites on construction vehicles. Once there, knapweed releases a toxin to inhibit the growth of other plants and begins its reign of domination.

If noticed quickly, a patch of knapweed can be pulled manually, but its long taproot makes getting the entire plant a crapshoot. If knapweed has spread to more than just a few clumps, it’s time to call for reinforcements from the county. Edsall says that the weed district office has information for landowners who want to stop the spread of weeds on their property. The county can provide weed identification booklets and a list of options regarding how landowners can best fight the weeds. Many times, Edsall says, she will go out and walk the property with the landowner.

If the weeds occur on public lands, a hiker may call in their location to the weed district, or a mapping crew may find the weeds. In the summer, weed survey crews head to the hills and enter into GPS units the exact location of weed infestations. This approach presents bits and pieces of data, rather than a countywide overview. But combined with these on-going efforts, a little help from modern technology could inhibit the spread of these weeds.

AquilaVision, a technology company, applies a high-tech hyperspectral camera to detect noxious weeds on a landscape scale. Here’s how it works. The hyperspectral/multi-lens camera is fitted underneath a Cessna or helicopter that flies a grid pattern over a section of land. Each time it goes out and back, the camera covers a mile-wide swath of land. The camera, though, isn’t your run-of-mill moviemaker. Rather than making black and white pictures, the camera records very subtle differences in color and reflectance. If it picks up a patch of knapweed, that patch gives off a different color than a patch of alfalfa, for example. The same goes for trees, patches of leafy spurge, houndstongue, etc. The data from the camera is processed in a computer, which can then pinpoint the exact location of the weed patches. So what does this mean for ranchers and homeowners?

AquilaVision is currently working with the Madison County Weed District to build a database so the weed commissioners have the information that can be used by weed fighters. Their “Weeds to Web” program will tell county weed districts exactly where weeds are in the area. Once the database is running full-bore, the program will even prioritize which patches should be treated based on their location, size, and propensity to spread.

“The essential package for weed management includes committed individuals, accurate information and adequate resources,” says Harve Kaufman, project coordinator for AquilaVision. “Weeds to Web is an integrated system that will help weed fighters locate and treat weeds—and help them measure the efficacy of their actions for future planning.”


How can you get involved or learn more?

  • Madison County Weed District, Margie Edsall, 313 East Idaho, Virginia City, MT 
  • Montana Weed Control Association, MWCA Executive Secretary, Becky Kington, P.O. Box 315, Twin Bridges, MT, 59754, office/fax - 406-684-5590
  • Noxious Weed Awareness and Education Campaign, Carla Hoopes, Project Coordinator, Bozeman, MT, 59717, 406-994-5683
  • AquilaVision Inc., 1121 East Broadway, Suite 105, Missoula, MT 59802, 406-532-3260,



~ PJ DelHomme recently completed his master’s of science at the University of Montana. He contributes to regional and national publications.