Along the trails of the San Juan National Forest, hikers have to hunt to find native plants like Golden Banner, Yarrow, and Cow Parsnip hidden amidst groups of noxious weeds.

To give these native plants a fighting chance, the U.S. Forest Service, in cooperation with Montezuma County and the local habitat partnership committee, will be spot spraying noxious weeds along trails in the Dolores river valley this summer.

Noxious weeds are defined by the San Juan Mountains Association as "non-native plants whose weapons can disturb or destroy a field of native grasses or flowers very quickly, unless controlled."

Mark Tucker, range conservationist for the Dolores Ranger District, is spearheading the weed control program. He said there is nearly a 30 percent infestation of non-native weeds in the district, and this is one way of controlling their spread.

The destruction to native habitat and land caused by non-native and noxious weeds is such a threat that it has brought ranchers and conservationiststogether.

"It seems like dealing with noxious weeds is one area that environmentalists and agriculturalists are in lock step," said Mark Pearson, chairman of the Sierra Club’s national wilderness committee. "Noxious weeds undermine the integrity of the ecosystem."

Currently, county officials are trying to contain 17 noxious weeds identified by the state and county, and trying to eradicate new species coming in from Utah.

"It’s an escalating problem that we need to deal with immediately," said Ann Rilling, executive director of Durango Nature Studies. "Otherwise we could lose habitat in the area."

To help control Canada and Musk thistle, the Forest Service is treating the weeds with blended herbicide along parts of the Priest Gulch, Bear Creek, Section House, and School House trails this summer.

Canada thistle was introduced from Europe and is a perennial that spreads by seeds and its horizontal root system. The stem of the plant is hollow, and can grow up to five feet tall. The flowers are small and compact, and are light pink to rose-purple.

"There is no way you can control it by pulling it," said Tucker.

Musk thistle is a biennial that grows in larger thistle clusters topped with round purple rosette flowers. It blooms in late May and June and sets its seed in June or July. Musk thistle can release up to 6,000 seeds per plant.

Both Canada and Musk thistle root on disturbed land areas, such as waste areas, roadsides, and pastures.

Tucker said that it is important for trail users to clean their pets and the cuffs of clothes and pants after their hike. They should also not park in weeds, or camp in weedy patches, because they might spread the seeds from the weeds when they move. Tucker said that recreationists should report the noxious weeds they see along the trail to the ranger station.

"We’ll never make any real progress until the average person realizes there’s a problem," said Tucker.

The blended herbicide is mounted on a pack horse in five-gallon syrup cans, with a bottle of carbon dioxide to power it through the hose to the rider. The whole system costs about $300, and allows the rider to spray herbicide off the saddle horse as he makes his way into remote forest areas.

Tucker said that the herbicide does not pose a threat to humans, animals, or native plants because the weed absorbs the chemical within minutes. The team, however, will be posting signs in the sprayed areas to warn recreationists of the presence of herbicide.

Spot spraying is one part of the forest service’s overall weed management plan, which uses cultural, biological, and chemical treatments of weeds.

Spotted Knapweed and Leafy Spurge are two of the most difficult area weeds to contain. Range managers will often use flea beetles to control large areas of these weeds. The beetle burrows into the root system, stresses the plant, and interrupts the nutrient cycle to weaken the plant.

Seed Head weavils are used as a biological control for Musk Thistle, but Tucker said that herbicides are the best method of controlling smaller patches of weeds.

Grazing can help certain native species to survive. Sheep can eat some noxious weeds, but for the most part grazing gives native species a better chance at survival. "Grazing is just one tool of many we can use," said Tucker.

Entomologists and range managers agree that weeds are tough to eradicate without integrated pest management.

"Weeds are the greatest threat to the environment there is," said Bob Hammon, an entomologist with Colorado State University.