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[SANET-MG] super resistant horse weed
The article below was found on GM watch!
Attack of the 12-foot horse weed
Herbicide-resistant strains plague California farmers
By Juliana Barbassa, Associated Press
Horseweed was once merely a nuisance to farmers hard to pull out, quick
to sprout back after cutting, and capable of towering over tractors.
Now, it's becoming a full-blown nightmare worthy of an agricultural
horror flick. Scientists in California have found clusters of the weed
that are resistant to scores of herbicides, leaving farmers to fight an
increasingly formidable and costly foe.
Pete Christensen said he watched his costs soar as the most popular
herbicide became increasingly powerless to stop the weeds from choking
the grapes on his 75-acre vineyard near Selma.
About five years ago, he started noticing that Roundup wasn't withering
the weed as usual. Three years later, he had tripled the concentration
of the herbicide, and had doubled the applications, but the weeds were
growing thicker than ever, rising over his vines and competing with them
for water, nutrients and sunshine.
"It was dominant in the landscape,' Christensen said.
The weed, also known as mare's tail, has always been around, but it
wasn't until last month that University of California researchers
confirmed that some strains of it had become resistant to herbicides,
posing a threat to the nation's most productive farmland.
Researchers were alarmed by the weed's rapid proliferation. Its spindly
stalks can be seen poking out of Napa Valley vineyards in the North,
along highways and pastures in the Central Valley and in Southern
Farmers elsewhere have been dealing with resistance to the chemical
glyphosate. First found in Delaware in 2000, glyphosate-resistant
horseweed has since been found in 10 other states in the East and South.
Farmers dealing with the problem have been forced to repeatedly till
their fields, rely on weeding, or on more toxic herbicides to control
the tall, fast-growing pest.
Developing resistance to a chemical isn't unusual among plants and
animals, scientists said. What makes the horseweed adaptation such a
nuisance is how fast it reproduces and how big it grows, sucking up
scarce water and nutrients as it stretces 10 or 12 feet tall.
As a relative of the dandelion, each weed produces up to 200,000 tiny
airborne seeds a season on fluffy yellow flowers.
For decades, growers, gardeners and anyone looking for an easy way to
beat back weeds have relied on glyphosate. It's inexpensive, works on
several types of weeds and is less toxic than other pest-control
Farmers planting Roundup-Ready crops such as corn, soybeans or cotton
that have been genetically engineered to survive the chemical could
spray it liberally over their entire field, killing all weeds and
leaving only their crops standing.
The herbicide's popularity may be partly to blame for breeding the
resistance, researchers said. By killing nonresistant weeds, it allows
only the survivors those few naturally resistant plants to thrive.
"They've created a problem by relying on one solution to solve all
problems,' said weed ecologist Anil Shrestha of the University of
California's Kearney Agricultural Center.
Some scientists said the development wasn't surprising.
Systems like Monsanto's Roundup-Ready crops, which promise an easy,
one-chemical solution to the age-old problem of weed control, only work
for a short time, said Margaret Mellon, director for the Food and
Environment Program at the Union of Concerned Scientists.
"When you expand the use of an herbicide dramatically, resistant weeds
start moving in," said Mellon.
Bob Prys, a manager for the 13,000-acre Borba Farms, said the weed
became a problem just three or four years after they started growing
Roundup-Ready cotton on the 500-acre ranch. They sprayed the field,
killing everything but the cotton plants, and saving money by having to
till their fields less frequently.
Now Prys said they're relying on weeding again and adding other
chemicals to their herbicide mix adding unexpected costs to the higher
price they pay for Roundup-Ready seed.
"It's caused us to re-evaluate our Roundup-Ready cotton,' Prys said.
Monsanto researchers recommend mixing in other chemicals to eliminate
the threat before there is a problem, said David Heering, the Roundup
technical manager for Monsanto.
"At the end of the day, they'll still have fewer passes through the
fields, and fewer weed-control problems,' Heering said.
The UC scientists recommended rotating crops, cultivating the land with
farm equipment, weeding, and using herbicides that kill the seeds in the
soil before they germinate.
Those measures will increase costs for farmers, but will prevent a more
serious and costly problem later on.
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