From: "Niel Ritchie" <[log in to unmask]>
Date: Fri, 11 May 2001
Subject: Biotech Soybeans Lead to More Use Of Herbicides, Not Less
Farm Bill News ([log in to unmask])
Posted: 05/11/2001 By [log in to unmask]
===============================
International Environment Reporter
Volume 24 Number 10
Wednesday, May 9, 2001 Page 378
ISSN 1522-4090
News
Pesticides
Biotech Soybeans Lead to More Use
Of Herbicides, Not Less, Report Claims
Soybeans genetically engineered to withstand applications of the herbicide
glyphosate (also know as Roundup) need to be treated with more herbicides
compared to conventional soybean varieties, a May 2 report from the
Northwest Science and Environmental Policy Center stated.
The genetically modified soybeans also produce fewer bushels per acre than
other soybeans, the report concluded, based on university experimental
trials.
"If reducing the pounds of herbicides applied per acre was among the
important goals shaping U.S. soybean weed management systems in the 1990s,
the introduction of Roundup Ready soybean varieties was a major step
backward," according to the report. The title of the report is Troubled
Times Amid Commercial Success for Roundup Ready Soybeans: Glyphosate
Efficacy is Slipping and Unstable Transgene Expression Erodes Plant
Defenses and Yields.
Many soybean herbicides are sold in "combination products" that contain two
or three active ingredients, the report said, and many of these have been
introduced to supplement weed control for Roundup Ready soybeans.
Reaction
Representatives of Monsanto Co. of St. Louis--the developer of the
soybean--and of the National Center for Food and Agricultural Policy took
issue with the report's conclusions.
No studies have shown an increase in pesticide use with the Roundup Ready
soybeans, Monsanto's Harvey Glick told BNA May 2. Glick, leader of global
biotechnology stewardship for Monsanto, said Roundup Ready soybeans
continue to be an effective tool for farmers to remain competitive in a
global market.
Roundup Ready soybeans allow farmers to spray a single broad-spectrum
herbicide active ingredient glyphosate (Roundup) over growing soybeans to
kill weeds.
Consultant Charles Benbrook, author of the report, said his work is the
first that he knows of that analyzes U.S. Department of Agriculture (USDA)
data at the "field level" for herbicide use in soybeans.
Benbrook said he conducted the analysis to correct "misinformation" he sees
from the biotechnology industry and its advocates.
Herbicide Use
According to the report, although the "best-case" scenario Roundup Ready
systems require less herbicide than the highest application rate
conventional systems, most Roundup Ready soybeans will be treated with
about 0.5 pounds per acre more herbicide than most conventional soybeans in
2001.
The report said one trend in herbicide use and Roundup Ready soybeans is
that most farmers growing the genetically engineered soybeans apply one to
three additional active ingredients, because of "slipping efficacy" of
Roundup.
The "efficacy slip" in Roundup occurs because of an accompanying shift
toward species of weeds that Roundup is not as effective on, Benbrook said.
Glick denied the existence of a drop in efficacy of Roundup and said
Monsanto has done more than 500 "side-by-side" commercial field trials in
four years, and there is a slight increase in yield with the Roundup Ready
soybeans.
Nationally, in 1998, there were 65.7 million total acres of soybeans
planted, with 36.7 million of them, or 55.8 percent, planted to
conventional varieties, the report said.
About 25.4 million acres, or 38.8 percent of the total soybean acres
planted in the country in 1998, were planted with Roundup Ready soybeans,
and 3.5 million acres were planted with other herbicide-tolerant varieties,
the report said.
The popularity of Roundup Ready soybeans has caused other herbicide makers
to lower their prices, encouraging heavier reliance on herbicides, the
report said.
On average soybean acres nationwide, farmers applied 1.17 pounds of
herbicide active ingredient in 1998, with an average of 0.92 pounds of
glyphosate per acre applied to 30.7 million acres, the report said. On
Roundup Ready soybeans, an average of 1.22 pounds of herbicide per acre was
applied, with 1 pound per acre of glyphosate.
Yield
Benbrook said the Roundup Ready soybeans produce 5 percent to 10 percent
fewer bushels per acre, contrasted to otherwise identical varieties grown
under comparable conditions.
Changes to the soybeans (including decreased nitrogen fixation) due to
application of Roundup can reduce their yield, the report added.
Fewer farmers will want to accept the trade-offs and costs involved with
Roundup Ready soybeans, especially with yield decreases, Benbrook said.
According to Benbrook, there are three lessons to be learned from the rapid
adoption of Roundup Ready soybeans, absent independent, nonindustry
research. First, any biotechnology that increases reliance on one pest
management tool, and especially one herbicide, "is headed for trouble."
Second, inserting genes into plants' metabolic pathways is a "risky
proposition" that is likely to lead to unanticipated consequences,
especially if plants are stressed by other factors, the report said.
Third, there was a lack of "independent" research on some consequences of
the soybeans until "well after" regulatory approvals and widespread
adoption, the report said.
Benbrook is based in Sandpoint, Idaho. Benbrook's center is a nonprofit
research and policy center.
The report was based in part on 1998 herbicide use raw data from the
Agriculture Department that have not been publicly available. These data
were specially tabulated by USDA's Economic Research Service for Benbrook.
Benefits of Roundup
The report said there are more herbicides used on Roundup Ready crops than
on other soybeans that rely on so-called low-dose chemicals.
However, Leonard Gianessi of the National Center for Food and Agricultural
Policy said the data on use of low-dose herbicides are deceptive.
A low-dose herbicide controls fewer types of weeds, and the use of
additional herbicides are necessary. Therefore, they are not really
"low-dose" herbicides when the other products are added in, Gianessi said.
The low-dose herbicides also are chemically active for up to four years in
the soil, Gianessi said. Glyphosate disappears immediately in the
environment because it binds to soil and soil microbes attack it, he said.
The low-dose herbicides present a challenge for sustainable agriculture
because if farmers want to rotate from nonengineered soybeans to wheat
after use of the low-dose products, for example, the herbicides still could
damage the wheat, he said. Soybean growers have rejected low-dose
herbicides because they have harmed the wheat, Gianessi said.
Weed Control Method
Contrary to Benbrook's report, Gianessi said low-dose herbicides work well
if weeds are less than 2 inches tall, but not so well for larger weeds.
Glyphosate kills weeds up to 6 inches tall, he said.
It is crucial to look at the variable of weed control method, Gianessi
said. Benbrook's report looks at yields in variety trials that compare
different soybean varieties, but these trials do not have the variable of
weeds, which are hand-pulled, Gianessi said.
These trials also do not consider the herbicide used to kill the weeds, he
added.
The alleged "yield drag" of Roundup Ready soybeans is actually a "lag," and
as the Roundup Ready soybeans are further developed, they are catching up
to conventional crops, Gianessi said. Research by Gianessi's center
indicates the yield disparity is more likely because of the need for
additional "backcrossing" using conventional breeding techniques.
Benbrook's report also did not use 1999 data, which indicate herbicide use
in pounds per acre decreased from 1998 to 1999, from 1.06 pounds per acre
in 1998, to 1 pound per acre in 1999, Gianessi said.
By Karen L. Werner
Copyright © 2001 by The Bureau of National Affairs, Inc., Washington D.C.
----------
Mark Ritchie, President
Institute for Agriculture and Trade Policy
2105 First Ave. South
Minneapolis, Minnesota 55404 U.S.A.
[log in to unmask] www.iatp.org
www.wtowatch.org, www.farmbillwatch.org
www.gefoodalert.org, www.sustain.org/biotech
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