By Myrna Trauntvein
Times-News Correspondent
Juab County to contribute funds for killing of noxious
weed
Squarrose Knapweed is a noxious weed that originally
arrived from Eurasia in the early 1900s and then got out of
hand.
A weed is nothing more than a flower blooming out of
place and the Bureau of Land Management (BLM) defines
Noxious Weeds as "A plant that interferes with management
objectives for a given area of land at a given point in
time,"
Squarrose knapweed is one of those plants that came
without the natural enemies that kept their numbers in check
in their country of origin. For that reason, Utah is
developing a cooperative effort to bring the weed under
control by using biological warfare on the weed.
"We are contributing $1,500 toward the program so that
Juab County can participate," said Wm. Boyd Howarth,
commission chairman.
The program is designed to put a dent in the squarrose
knapweed spread in Juab County, for one, and also in other
counties where the noxious weed has become a problem.
Like other problems with creatures and weeds in other
spots of the world, it is probable that knapweeds were
accidentally introduced as a contaminant of alfalfa
seed.
Today, knapweeds are found in all states west of the
Rocky Mountains, with infestations in Utah, Montana, Idaho,
Washington, and Wyoming.
These weeds are spreading at rapid rates throughout
Utah, with dramatic impacts to native plant communities.
Knapweeds are aggressive competitors and reduce
biodiversity by out competing native vegetation. They form
dense infestations in disturbed as well as undisturbed
areas, cultivated fields, grain fields, pastures, along
roadsides, and ditches. Studies show that soil and water
losses can be caused by knapweed infestations. Knapweed may
also cause soil erosion, decrease biodiversity, and reduce
forage for wildlife and livestock.
Bureau of Land Management Field Offices are doing all
they can using chemicals to fight back against squarrose
knapweed, however, chemical control will not reach out to
inaccessible areas.
Therefore, in Utah BLM's integrated pest management
program officials are actively working to release the
specific insects that are the plant's natural enemies, and
are funding research for other species.
"In these programs, it is wise to be certain that we
are not creating another problem thinking that we are
eliminating a one," said Howarth.
In literature sent to Juab County Commissioners, BLM
officials said extensive research is done to insure that the
insects are specific to the target plant species, and they
will not attack other plants, such as native plants and food
crops.
One major problem with insect release projects is the
difference in climate between where the insects are
collected and where they are released. Many times it takes
several years of releases before some insects become
climatized and start to reproduce.
Unfortunately, many species studied never reach the
reproductive stage, therefore they don't propagate and
spread to other weeds.
Two seed head flies are established on squarrose
knapweed. These are the Banded gall fly, Uropbora affinis,
and the UV knapweed seed head fly, Uropbora
quadrifasciata.
Several other species have been released as part of
the research effort, but none have become established.
In Utah, research is being conducted using several
other insect species that are specific to noxious weeds.
Jeff Banks, Juab County USU Extension agent, said the
squarrose knapweed problem in Utah is serious.
"Several programs are being used to control the
spread of the noxious weed," he said.
Even though many people are not yet aware there is a
problem with noxious weeds and some people and agencies are
just beginning to realize the seriousness of the problem, it
is a serious one.
A common perception is that much of BLM administered
lands in Utah are too dry for weeds.
The following examples illustrate how susceptible Utah
could be to noxious weed infestations.
Squarrose knapweed, has spread from a few plants in
1954 to 140,000 acres in 1996 within a 8-12 inch
precipitation zone in Utah.
Spotted knapweed was first identified in Montana in
the 1920s. It now covers 5 million acres in that state
alone.
Without major increased exotic plant management
efforts, these aggressive plants will continue marching
through rangelands and farms.
To maintain a healthy ecosystem is a primary goal of
the BLM. One of the greatest obstacles to meeting this goal
is the rapid expansion of noxious weeds. These weeds can
dominate many sites and often cause permanent damage to
native plant communities.
Noxious weeds are increasing on western BLM
administered lands at approximately 2300 acres per day, but
it is also important to remember that 95 percent of BLM
administered lands are not yet significantly infested.
Therefore, it is imperative that we apply effective
and economical strategies that are available to immediately
protect those lands from weed infestation.
BLM recognizes that controlling weeds must be a
cooperative effort. There are many ongoing efforts with our
partners that must be continued, and new cooperative efforts
and partnerships established. The BLM in Utah is committed
to establishing partnerships with State agencies, County
governments, Universities, local Extension service, Native
American tribes and public interest groups to continue the
effort to prevent and control new and existing noxious weed
infestations. The effort will require cooperation from all
concerned, because noxious weeds affect use and enjoyment of
the land, both public and private.
The results of the knapweed biological control program
are now evident. A stunning decline in plant density and
vigor where insects have been established for several years
has occurred. The best results are where the seed-head
weevils (Larinus spp.) and the two root feeders
(Cyphocleonus achates, Agapeta zoegana) are present.
Other insects such as knapweed flower weevil, spotted
knapweed seed head moth, sulphur knapweed moth and knapweed
root boring weevil are doing a great job of causing declines
in plants.
Biological control does not aim to eradicate weeds,
but to keep them at low, manageable levels.
After their introduction, biocontrol agents can take 5
to 10 years to become established and increase to numbers
large enough to reduce the density of the target weed. Once
established, effective biological controls provide an
inexpensive, long-term, and non-toxic means to control weed
populations. It is important to match the insect to the weed
management site. Insects have specific requirements for
growing and thriving.
"Several knapweeds, as they are known, are serious
noxious weeds in our state. Knapweed comes from the rounded,
knobby flower knap and is an older English form of 'knob,'"
said Larry A. Sagers, Deseret News garden columnist.
He said knapweeds are cousins of good old-fashioned
flowers known as cornflowers, bachelor's buttons, bluet,
basket flower or the old-fashioned blue-bottle. They are all
members of the genus Centaurea, a diverse group of many
different species.
Squarrose Knapweeds infest thousands of acres of land
in Utah. They are also known as "hurt sickle" because the
tough stems of the plants would dull or break a farmer's
sickle back the days of hand-reaping.
The plant prefers our Utah soil and are also drought
and heat tolerant.
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