They race across the West covering 2,300 acres each
day, devouring an area the size of twenty Wal-Mart superstores
every minute. They reduce habitat for wildlife, dry up water tables
and intensify the threat of wildfires on 35 million acres of public
land. As the area covered by invasive plants grows, so does the
amount of money and effort put into their control. Now, the U.S.
Bureau of Land Management plans to triple the acreage it sprays for
noxious weeds and flammable brush. The agency just released a final
plan that allows herbicide spraying on nearly a million acres,
mostly in Nevada, Idaho, Wyoming and Oregon; introduces four new
herbicides and phases out six others; and establishes procedures
for evaluating new chemicals as they come on the market.
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.
Bureau of Land Management: Final Vegetation Treatments Using Herbicides Programmatic Environmental Impact Statement – BLM
Sagebrush Sea: http://www.sagebrushsea.org/
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