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  • From: "Tradingpost" <tradingpost@gilanet.com>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Herbicide-resistant strains plague California farmers
  • Date: Mon, 15 Aug 2005 12:46:28 -0600

Herbicide-resistant strains plague California farmers
By Juliana Barbassa, Associated Press
http://www.sgvtribune.com/Stories/0,1413,205~24512~3003075,00.html

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 California
fields.

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 ingredients.

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.





  • [Livingontheland] Herbicide-resistant strains plague California farmers, Tradingpost, 08/15/2005

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