July 8, 1996
Australian Ryegrass Resists Glyphosate
According to recent newspaper reports, researchers in
Australia have discovered a weed that is resistant to
glyphosate, a widely used herbicide. Earlier this year, a
farmer in Echuca, northern Victoria, found annual ryegrass on
his property that was not being controlled by Roundup,
Monsanto's trade name for glyphosate. The farmer noticed that
weeds in one field were no longer susceptible to the
herbicide after only 10 sprayings in the past 15 years.
Researchers at the Centre for Conservation Farming at Charles
Sturt University in New South Wales conducted studies that
confirmed the weeds were resistant to glyphosate. Director of
the Centre, Professor Jim Pratley, said that his research
team had performed two sets of tests on the weeds to confirm
resistance to the herbicide, and found that some of the
ryegrass survived almost five times the recommended dose.
Monsanto, a U.S.-based multinational corporation, stated that
they will send a team of researchers to the farm within the
next month to examine the ryegrass. Monsanto Australia's
technical director, Dr. Bill Blowes, said the company was
working with the university to confirm the cause of the
resistance in the trials conducted there. Earlier this year,
Monsanto announced plans to invest nearly US$200 million over
the next three years to expand manufacturing and formulation
capacity for Roundup. Sales of the herbicide played a key
role in the 11% increase in Monsanto's agrochemical sales in
1995.
Glyphosate is a broad-spectrum herbicide widely used to kill
unwanted plants both in agriculture and in nonagricultural
landscapes. It is viewed by some as a key component of
conservation or "no-till" farming. In the United States,
glyphosate is the eighth most commonly used herbicide in
agriculture and the second most commonly used herbicide in
nonagricultural situations. Estimated annual use in the U.S.
according to the U.S. Environmental Protection Agency (EPA)
is between 15 and 20 million pounds in agriculture and
between 4 and 6 million pounds for other uses.
In an interview in "The Australian," Professor Roger Cousens
of La Trobe University, Melbourne, one of Australia's leading
weed ecologists, warned that high-technology crop production
systems were entirely reliant on herbicides. According to
Professor Cousens, these farming systems are "in danger of
crashing down around our ears" because of the development of
weeds resistant to herbicides. Australia has more herbicide
resistance than any other major crop producing region in the
world. Ryegrass, the most common weed in Australia, is
resistant to various herbicides across 40% of the country's
agricultural region.
Professor Cousens stated that Australia needs to adopt a far
more ecological approach to the management of weeds,
integrating a range of other control methods and using
chemicals only sparingly.
Dr. Chris Preston of Adelaide's Cooperative Research Centre
for Weed Management stated that discovery of resistance to
Roundup could affect proposals to introduce genetically
engineered glyphosate-resistant crops in Australia. Monsanto
has gentically engineered glyphosate-resistant cotton and
soybeans which have been approved for use in the U.S.; the
company is currently seeking U.S. approval of glyphosate-
resistant canola and is developing engineered glyphosate-
resistant corn. In addition, five other genetically
engineered glyphosate-resistant crops have been field tested
in the U.S.: wheat, sugar beets, lettuce, potato and poplar.
Sources: The Sunday Herald Sun, June 23, 1996; The
Australian, June 20, 1996; The Canberra Times, June 19, 1996;
Financial Review, June 14, 1996; Glyphosate, Part 1:
Toxicology, Journal of Pesticide Reform, Fall 1995; Agrow,
May 3, 1996; Agrow March 29, 1996; USDA Animal and Plant
Health Inspection Service, data bases on notifications and
applications for field testing genetically engineered
organisms, http://www.aphis.usda.gov/bbep/bp.
Contact: PANNA
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