Think of it as a thin layer of sponge covering your pastures, soaking up moisture and smothering the ground. Or, maybe it's like armor, plating large areas of rangelands across the West.

When precipitation events are mild, clubmoss tends to absorb and hold nearly all available water in its above-ground vegetative mat and extensive, fibrous root system — making nearly all accumulated precipitation unavailable to other species.

Dense clubmoss is indigenous to the U.S., says Tracy Brewer, a Montana State University (MSU) range science researcher. And, while it certainly has the potential to be extremely problematic on Western rangelands, it's not considered a noxious weed.

“The economics of clubmoss revolve around costs and benefits of various treatments,” she says. “However, it's important to keep in mind that the results of treatment will vary on a site-to-site basis, and costs and benefits associated with treatments will vary.”

Mechanical Treatment Pays Off

Ranchers and researchers have been using various treatments to evaluate the effects of chiseling clubmoss on herbage response. In one MSU study, production increased between 250 and 400 lbs./acre on chiseled rangeland two years post-treatment.

Cost for chiseling is about $10/acre for once over and $18/acre for twice over. These costs are for labor and equipment but don't include seed.

“Chiseling rangeland for clubmoss control in eastern Montana is almost always profitable,” says Kent Williams, Custer County Extension agent. He says grass production can increase 2-3 times over unchiseled areas. In one study in a 13-in. precipitation zone, a $10/acre profit was realized with a treatment lasting 15 years.

People have tried different approaches when chiseling, Williams says, including broadcasting alfalfa seed with the treatment. “Interseeding rarely works though, because of the strong competition from the existing grasses,” he says.

Neither does dragging tires or harrows while chiseling.

“This decreases the treatment life as it smoothes the surface and allows it to fill in quicker over time,” Williams says. “Also, we warn ranchers that there's usually a huge increase in fringed sagewort the first years following treatment that decreases quickly as the grasses respond and get healthier.”

Williams believes the best response is with a one-time treatment.

“I'd rather see a guy chisel twice as many acres as go over the ground twice,” he says. “But, if you're getting cost-share for the treatment, you need to follow the recommendations of those cost-sharing the project.”

Light grazing after the grass goes dormant the year of chiseling, and proper grazing management in the years after, greatly enhances the treatment life, he says.

Jed Evjene, Two Dot, MT, is testing two types of implements that cause less surface disturbance than chiseling. He manages the American Fork Ranch in central Montana, which runs about 1,200 mother cows and several hundred yearlings.

He's comparing the effectiveness of a Tar-King Plant-O-Vator and a Lawson Aerator with both fall and spring treatments. The idea is to disturb the plants and allow moisture to penetrate the “armor” that clubmoss creates over the soil, he says.

“Dense clubmoss is a big problem on this ranch and we need to try everything available to get control of it,” Evjene says. “We see a 50% drop in grass production in areas it's spreading.”

Vegetation response and the cost/benefit ratios of these clubmoss control treatments will be measured this summer and through 2005.

When chiseling clubmoss, Jeff Mosley, MSU Extension range management specialist, suggests a tool bar fitted with 3- or 4-in. twisted shanks on 12-in. centers. He likes to travel at about 3.0-3.5 mph and chisels on the contour.

“Chisel in early spring, as soon as frost gets out of ground,” he says. “We don't chisel later than June 15 here in Montana.”

Late-fall chiseling also works well, Williams says. Adding fertilizer when chiseling improves grass response, but not enough to make it pay.

“The biggest drawback to chiseling is the physical nature of the site after chiseling,” says Mosley. He warns that runoff from clubmoss sites needed to fill up stock ponds may be decreased following chiseling.

Chemical Treatments Work

Various herbicide treatments have proven effective for controlling dense clubmoss, especially in areas inaccessible for mechanical treatment.

“Spring herbicide applications are slightly more effective,” Brewer says. “Surfactants are generally necessary for dense clubmoss, as leaves are small, hairy, and rolled and tipped at the ends, which make them fairly resistant to chemical control.”

One advantage of chemical control is that clubmoss's erosion-protecting properties aren't destroyed until other vegetation has established, she says.

Grazon® herbicide at 2 pints/acre, or a tank mix equivalent of Tordon® plus 2,4-D, may be effective. Cost for this type of herbicide treatment, with labor and ground equipment, averages $15-$17/acre.

Such herbicides will kill some, but not all, of the clubmoss. Increased grass production following herbicide application in some cases may be augmented by broadleaf forb control along with clubmoss control.

Brewer says clubmoss tends to increase in drought conditions, and careful grazing management is necessary to maintain the competitive advantage of desired plant species on a site.

Evjene emphasizes that his approaches to clubmoss control are part of an overall range management effort.

“We're also working on range monitoring as well as livestock rotations,” he says. “These things are all tied together. And really, in order to have an impact on one plant species or community, you need to put it into perspective with the management of the entire ranch.”