A dustup over weed control

The BLM's plans to spray nearly a million acres with herbicides have some environmentalists fuming, but many biologists and land managers welcome the policy

 

LASSEN COUNTY, CALIF., where the high desert meets the Sierra Nevada, offers wide-open vistas of juniper and sagebrush, and habitat for rare wildlife such as sage grouse and Carson wandering skipper butterflies. U.S. Bureau of Land Management botanist Carolyn Gibbs started fighting weeds here as a graduate student in 1994. She spent her summers pulling yellow star thistle, public enemy number one for the coalition of groups and agencies that became the Lassen County Special Weed Action Team. Today, the "Weed Warriors" target all the noxious weeds in the county, including cheatgrass and the lesser-known but even more insidious medusahead, and Gibbs is looking forward to a new tool in her fight against these two explosively flammable grasses: Plateau, an herbicide that she says leaves most native plants unharmed. The BLM is set to approve its use this fall, when it issues its final decision on an herbicide plan. 

The plan allows spraying for weeds and flammable brush on nearly a million acres of public land, mostly in Nevada, Idaho, Wyoming and Oregon. It introduces four new herbicides, re-authorizes 14 already in use and phases out six others, giving BLM staff access to an arsenal of 18 chemicals. The plan replaces a policy of approving herbicides in batches every decade or so with an ongoing, case-by-case review of new chemicals; it also adds new categories of risk assessment, such as effects on sensitive species and Native American harvest rights. 

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 saying that the threat posed by weeds outweighs that from herbicides. 

Invasive weeds degrade wildlife habitat, dry up water tables and intensify wildfires on 35 million acres of public land across the West. They invade 2,300 acres each day - equal to 20 Wal-Mart superstores a minute. "Weeds are a big problem throughout the West, and herbicides are a critical tool for dealing with them," says Jerry Holechek, range scientist at New Mexico State University near Las Cruces. He says creosote, a native shrub that encroaches on grasslands because of fire suppression, "totally dominates" the landscape there. Because manual creosote removal tears up the soil, and the diminished understory makes prescribed burns ineffective, Holechek believes herbicide use is the only realistic option for restoring the grasslands. 

Gibbs compares using herbicide to putting antiseptic on a wound to give the body' healing processes an edge over bacteria. The West is crawling with examples of what happens when infection spreads. In Montana, a 40,000-acre spotted knapweed invasion in the Selway-Bitterroot Wilderness has reduced elk forage in some places by 70 percent, according to Jerry Asher, who spent 11 years with the BLM educating the public about noxious weeds. Perennial pepperweed came to Lassen County in 1996, Gibbs says, and now infests 64,000 acres, where it threatens habitat for the endangered Carson wandering skipper. And squarrose knapweed, discovered in Utah 40 years ago, now covers hundreds of thousands of acres, according to Brian Amme, project manager for the BLM's Western vegetation management program. 

OF COURSE, NOT EVERYONE likes the idea of spraying a million acres of public land - triple the current area treated. "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. She cites picloram, which is already used by the BLM for woody plant control and is re-authorized in the new plan: She says it is highly toxic to other plants, persists in the soil and contaminates water. Moreover, she says, "since weed seeds specialize in colonizing empty areas, herbicides will be used again and again." 

"Everyone appreciates the severity of the weed invasion problem," says Mark Salvo, director of the Sagebrush Sea conservation organization. However, he says, the BLM is managing for weeds while still allowing the activities that cause invasion in the first place, such as grazing and ORV use. Critics also cite damage to farmland, such as an incident in 2002 when drift from BLM lands sprayed for cheatgrass with Oust, an herbicide re-authorized by the new plan, caused millions of dollars in damages to nearby beet fields. 

The BLM's plan prescribes buffers between treated areas and cropland, but "sometimes things are outside your control," says Amme, adding that farm chemicals also drift onto public lands. Amme says all BLM weed-control projects include rehabilitation, such as replanting in sprayed areas. And although the agency' efforts involve both control and prevention, "if all activities related to humans were removed from Western federal lands tomorrow, the weeds would continue to spread rapidly," says Asher. He points out that livestock were removed in 1900 from the area that' now the Selway-Bitterroot Wilderness, but knapweed didn't arrive until after 1920. Grazing was stopped long ago in Idaho' Craig Mountain Wildlife Management Area, but weed invasion continued. 

A flexible approach, using chemicals alongside other methods, works best, according to Amme: "You look at the conditions and choose the best tools for the job." Lassen County' team uses an integrated pest management approach, including targeted grazing, chemicals, biocontrol, burning, and hand digging, and has achieved some startling victories: They've reduced the invasion of yellow star-thistle from over a hundred populations in 1994 to three today. But the biggest successes in weed management are the ones you never hear about, according to Amme - ordinary people digging up a few plants before they spread. "The story of the West is (that) local people usually don't get too concerned ... until it' too late," says Asher. "What we're really talking about is saving land." 

The author just finished her tenure as an HCN intern.