Herbicides are a powerful weapon in the war on weeds, but many environmentalists fear collateral damage. The biologists and land managers on the front lines, however, seem nearly unanimous in agreeing that the threat to ecosystems posed by noxious weeds outweighs that from herbicides.
“Weeds are a big problem throughout the West, and herbicides are a critical tool for dealing with them,” says Jerry Holechek, a range scientist at New Mexico State University near Las Cruces. He says that creosote, a native shrub that has been encroaching on grasslands because of fire suppression, “totally dominates” the landscape near Las Cruces. Because manual creosote removal tears up the soil, and the absence of an understory prevents managers from burning, he believes herbicide use is the only realistic option for restoring the grasslands.
Carolyn Gibbs, a BLM botanist who runs Lassen County’s Special Weed Action Team, compares using herbicide to putting an antiseptic on a wound to give the body’s natural healing processes an edge over bacteria. The West is crawling with examples of what happens when an infection is allowed to spread. In Montana, where spotted knapweed and leafy spurge cover millions of acres, a 40,000-acre infestation in the Selway-Bitterroot Wilderness has increased runoff and damaged streams, and knapweed has reduced the amount of elk forage by up to 70 percent in some areas, says Jerry Asher, who spent 11 years with the BLM educating the public about noxious weeds. In California, yellow star thistle has invaded between 15 and 20 million acres, according to Brian Amme, project manager for the BLM’s Western vegetation management program. Squarrose knapweed was discovered in western Utah only 40 years ago, but it now infests hundreds of thousands of acres. And cheatgrass, one of the West’s most widespread weeds, acts as a potent fuel for wildfire.
Of course, not everyone likes the idea of spraying a million acres of public land. “Some of the herbicides proposed have the potential to dramatically impact plants outside the spray area,” says Kay Rumsey, spokeswoman for the Northwest Coalition Against Pesticides. Moreover, she says, “since weed seeds specialize in colonizing empty areas, herbicides will be used again and again.” Critics also cite damage to farmland, such as an incident in 2002, when drift from BLM lands sprayed for cheatgrass caused millions in damages to nearby beet fields. “Everyone appreciates the severity of the weed invasion problem,” says Mark Salvo, director of the Sagebrush Sea, which conserves sagebrush ecosystems. His organization is concerned that the BLM is managing for weeds while still allowing the activities that cause weed invasion in the first place, such as grazing and ORV use.
The BLM’s plan prescribes buffers between treatment areas and cropland, but “sometimes things are outside your control,” says Amme. He says that all BLM weed-control projects include rehabilitation work, such as replanting native species in areas that have been sprayed. And according to Asher, though the agency’s efforts involve both control and prevention, even “if all activities related to humans were removed from Western federal lands tomorrow, the weeds would continue to spread rapidly over vast areas.” He points out that livestock was removed in 1900 from the area that is now the Selway-Bitterroot Wilderness, but the knapweed didn’t arrive until after 1920. Grazing was stopped long ago in Idaho’s Craig Mountain Wildlife Management Area, but the weed invasion continued.
A flexible approach that uses chemicals as well as other methods gets the best results, says Amme. “You look at the conditions and choose the best tools for the job.” For example, Gibbs says Lassen County’s integrated pest management approach, which includes targeted grazing, chemicals, biocontrol, burning, and hand digging, has reduced yellow star thistle from over a hundred populations in 1994 to only three today.
The biggest successes in weed management are the ones you never hear about, according to Amme — ordinary people going out with a shovel to dig up a few plants before they can spread. “The story of the West is (that) local people usually don’t get too concerned…until it’s too late,” says Asher. “What we’re really talking about is saving land.”
Public comment on the herbicide plan is open until July 31.