GM crops do not reduce the use of pesticides, report shows (15/12/2004)

The two articles below are from Farmers Weekly interactive - the website of the UK's biggest selling publication for farmers - and they report on an important US study released this autumn that showed that "the biotech industry's claims that GM crops help reduce the use of pesticides are unfounded".

Interestingly, the report has received little coverage in the US despite the fact that the author of the study is one of the America's leading independent agronomists. Dr Charles (Chuck) Benbrook served as the agricultural staff expert on the Council for Environmental Quality/The White House before moving to Capitol Hill where he was the Executive Director of the Subcommittee of the House Committee on Agriculture with jurisdiction over pesticide regulation, research, trade and foreign agricultural issues, and oversight of the USDA.

Chuck Benbrook was recruited to the job of Executive Director, Board on Agriculture of the US's National Academy of Sciences, in early 1984. During his seven-years as Executive Director, he helped establish the Board as a major voice on agricultural science and regulatory policy.

In late 1990, he formed Benbrook Consulting Services. Several Board on Agriculture projects in the 1980s addressed "the promise of agricultural
biotechnology". As a long-time expert in pesticide regulatory law, Benbrook's work extended to agricultural biotechnology issues in the early 1990s.

Benbrook is the Director of the Northwest Science and Environmental Policy Centre and has a PhD in agricultural economics from the University of Wisconsin-Madison and an undergraduate degree from Harvard.

The full report 'Genetically Engineered Crops and Pesticide Use in the United States: The First Nine Years' can be found at www.biotech-info.net.

Weedkiller rise in GM crops
By Farmers Weekly Staff
Source: FWi, 26 November 2003

GROWING genetically-modified crops has caused US farmers to step up herbicide use, according to a new study.

The report, released on Tuesday (25 November) by the Northwest Science and Environmental Policy Centre, claims to be the first major study into pesticide use on commercial GM crops.

In their first three years of commercial sales in the US (1996-1998), pesticide use on the GM acreage reduced by about 11,500 tonnes, says the report.

But increases in the last 3 years have pushed up herbicides on GM crops by more than 33,100 tonnes.

The report was funded by a number of US ecological, consumer and organic farming organisations.

It draws on official US Department of Agriculture data on pesticide use by crop and state over 223 million ha (550 million acres) of GM corn soya and cotton.

Substantial increases in herbicide use on herbicide-tolerant crops, especially soya, accounted for the increase in pesticide use on GM crops compared to conventional varieties, said the report.

Many farmers have had to spray incrementally more herbicides to keep up with shifts in weeds towards species that were harder to control.

This was coupled with the emergence of genetic resistance in certain weed populations, claimed the report.

"For years weed scientists have warned that heavy reliance on herbicide-tolerant crops would trigger ecological changes in farm fields that would incrementally erode the technology's effectiveness," said report author Dr Charles Benbrook.

"It now appears that this process began in 2001 in the United States in the case of herbicide tolerant crops."

"This new report is yet another blow to the GM industry which has hailed the supposed reduction in farmland chemicals as the main benefit of growing GM crops," said Friends of the Earth GM campaigner Clare Oxborrow.

GM weedkiller use increases
By Farmers Weekly staff
Source: FWi, 28 October 2004

A NEW study reveals that while US pesticide use dropped during the three first years of commercial GM crop cultivation, it has increased sharply thereafter.

GM maize, soybeans and cotton have led to a 55,000 tonnes increased in pesticide use since 1996, according to the study published by the Northwest Science and Environmental Policy Center.

The study, conducted by Charles Benbrook, a former Executive Director of the Board on Agriculture of the US National Academy of Science, therefore concludes the biotech industry's claims that GM crops help reduce the use of pesticides are unfounded.

But the study differentiates between herbicide tolerant crops (HT) and crops genetically engineered to express the bacterial toxin Bacillus thuringiensis (Bt), which is toxic to many insects, and it shows that on the latter crops pesticide use
has dropped.

Bt crops have helped reduce insecticide use by 7,000 tonnes from 1996, while herbicide use on HT crops has increased by 62,000 tonnes.

The overall pesticide use has risen by about 4.1% on the US GM acreage, according to the study.

Reliance on a single herbicide, glyphosate, as the primary method for managing weeds on millions of acres planted to HT varieties is said to be the main factor that has led to the need to apply more herbicides per acre to achieve the same level of weed control.

Average application rates of glyphosate in HT weed management systems have jumped sharply in the last few years, the reports says, because of:

-The spread of glyphosate-tolerant or resistant marestail (also known as horseweed)
-Shifts in the composition of weed communities
-Substantial price reductions and volume-based marketing incentives from competing manufacturers of glyphosate-based herbicides

The study predicts that for the foreseeable future, HT crops will increase pesticide use more than Bt crops will reduce it, in part because HT crops are grown on a much larger area than Bt crops.

The study is based on official US Department of Agriculture data on pesticide use over 670m acres of GM maize, soya and cotton.

The study is available for download here:

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