weeds of mass destruction
threatens wildlife habitat, rangeland
weeds have become a threat to our way of life. If we donít get on top
of it, it will destroy our whole ecosystem."
of a three-part series
Express Staff Writer
invasion, often taking the form of a lovely purple flower, is spreading
terror into the hearts of Blaine Countyís native vegetation.
noxious weeds, the foreign invaders have few natural controls and spread
rapidly through pastures, forests and riparian areas. They annihilate
food plants for wildlife and livestock, choke waterways and create spiky
thickets impenetrable to hikers and anglers. Even after a stand of the
invaders is wiped out, their seeds can lay dormant for 10 years before
weeds have become a threat to our way of life," said County
Commissioner Sarah Michael. "If we donít get on top of it, it
will destroy our whole ecosystem."
County Weed Superintendent John Cenarrusa conducts a field seminar
on identification of noxious weeds that have invaded the Wood River
Valley. Express photo by Willy Cook
species of plants have been designated "noxious" in Idaho.
Once designated, the plants fall under a state law that requires
landowners to eradicate them.
Europe or the Middle East, the plants have been introduced to the United
States at various times and in various places. Some have been brought in
intentionally as flowering plants, others accidentally as seeds hidden
in shipments of other products or stuck to the clothing of immigrants.
weeds dominate about 70 million acres of private, state and federal land
throughout the West. The U.S. Bureau of Land Management believes the
weeds are spreading on federal lands at the rate of about 2,300 acres
too many public land watersheds are rapidly undergoing what is perhaps
the greatest permanent land degradation in their recorded history,"
stated two BLM scientists in a paper delivered to The Governorís Idaho
Weed Summit in Boise in 1998.
Department of Agriculture estimates that noxious weeds cause $300
million in damage to the stateís lands each year.
widespread noxious weed in Blaine County is spotted knapweed. The plant
grows about 3 feet tall and has pinkish-purple, thistle-like flowers. It
is common along roads.
knapweed, native to Europe, is thoroughly established in North
knapweed is thought to have entered the United States at the San Juan
Islands in Washington in 1893, and spread east from there. The plant was
first noticed in the Wood River Valley in the 1950s.
native Europe, spotted knapweed faces predators and other plant species
with defenses against its spread, and so exists in only scattered
patches. This is not the case here.
crowds out native plants and forms a monoculture," said Seth Phalen,
rangeland management specialist with the Sawtooth National Recreation
Area. "It really messes with the local ecology."
estimates that spotted knapweed covers 500 acres on the SNRA. About 200
acres of that is one infestation near the base of Durrance Mountain,
north of Ketchum.
plant adds a splash of color along roadsides in mid summer. But it
destroys elk habitat, increases the rate of erosion and wipes out native
wildflowers. Spotted knapweed out-competes native plants for soil
nutrients and water, and secretes a toxic substance that kills
surrounding plant species. Each plant produces about 25,000 seeds
Russell, fire use specialist with the BLMís Shoshone field office,
said spotted knapweed is slowly but surely squeezing out elk populations
in south-valley side canyons, an important winter range. He said the
plant got a toehold along roads, and is spreading up the hillsides. The
farther it gets from roads, the harder it is to eradicate.
has the potential to be a major problem," Russell said.
called leafy spurge is a major invader in the south county. It
aggressively colonizes riparian areas, and has become widespread along
the Little Wood River and Silver Creek. It contains a milky substance
that poisons livestock and wild animals, and can cause permanent
blindness in humans if itís rubbed into oneís eyes. Protection is
needed when handling it.
it gets onto farmland, you can pretty much write off that ground for a
couple of years," said Blaine County Weed Superintendent John
Cenarrusa. "Youíve got to use such harsh herbicides that it kills
the fertility of your soil."
ripe seed capsules rupture when touched, throwing seeds as far as 15
invasive species in the valley include:
Yellow Starthistle, which is native to the Mediterranean and Asia.
It is spreading in the area north of Hailey. It grows up to six feet
tall and has yellow, dandelion-like flowers and sharp spines on its seed
heads. Horses and cattle that graze on the plant can die a painful death
from ingesting its spikes.
Dyerís Woad, introduced to North America from Europe in the 17th
century, and cultivated as a source of blue dye. It is spreading in the
south end of Blaine County.
Yellow toadflax, which has orange and yellow snapdragon-like
flowers and was probably introduced from Europe as an ornamental. It has
spread across about 600 acres in the Sawtooth Valley, especially near
toadflax, native to the Mediterranean area, also has pretty yellow
flowers. It dominates about 20 acres near Boulder Creek in the Boulder
live in such a mobile societyóthere are always new invaders coming
in," Cennarusa said.
that may be poised to invade Blaine County from the south is purple
loosestrife. It is a semi-aquatic plant with large purple flowers.
is a gorgeous weed," said Ron Thaemert, Blaine County extension
agent for the University of Idaho Extension Service.
beauty disguises an evil heartóthe plant sucks the oxygen out of the
water in which it lives, killing the fish. Purple loosestrife grows in
solid stands, crowding out food plants needed by ducks and geese, and
reducing suitable nesting sites.
just hope we donít ever get that here," Thaemert said. "I
cringe. In Silver Creek, it would just be devastating."
spread of noxious weeds in Blaine County is accelerated by human
activity. Grazing sheep, dogs and motor vehicles carry seeds. Seeds may
be carried north by sanding trucks loading up near Shoshone. Spotted
knapweed is one of the first plants to colonize areas disturbed by
development, and it does well in areas recently burned.
BLM scientists at the 1998 Boise weed summit concluded their
presentation by saying, "We have just begun to see the scope of the
massive degradation that will occur in the futureóif we allow that to
week: Part 2ó"The Counterattack")