Re: Does using GMOs really increase pesticide use?
Bill Freese
[Blog comment] November 25 2009  
http://geneticmaize.squarespace.com/blog/2009/11/24/does-using-gmos-really-increase-pesticide-use.html?lastPage=true#comment6424193

Anastasia's review of Dr. Benbrook's report is superficial and biased in several ways. The most glaring defect is one shared with the industry-funded PR team of Brookes and Barfoot (aka PG Economics, Ltd) and other biotech industry front groups like NCFAP (see Chapter 6 of Benbrook's report for a devastating rebuttal to the methods and results of these bogus "simulation studies"). Absolutely no mention, much less discussion, of the major factor driving increased pesticide use with GE crops - an epidemic of glyphosate-resistant weeds triggered by the excessive reliance on glyphosate fostered by Roundup Ready crop systems. The report (Chapter 4) gives a fully documented discussion of this increasingly serious agronomic problem, which has become a major topic of discussion in the agricultural science literature and in the farm press (see pages 34-40 for anyone interested in the truth about this matter). In brief:

Glyphosate-resistant pigweed (Palmer amaranth) infests millions of acres of cotton/soybean land in the South and is regarded by experts as a major threat to the cotton industry in the South - one impact has been the increase in manual weeding in cotton, something not seen for decades. Resistant horseweed (marestail) is even more extensive, and along with glyphosate-resistant giant ragweed is becoming a huge problem in the Midwest. All told, there are biotypes of nine weed species that have evolved resistance to glyphosate in the U.S. (all but one reported since the year 2000), and collectively they infest millions of acres (this doesn't even account for weed shifts to glyphosate-tolerant weed species like lambsquarters). It is perfectly clear that these tolerant and resistant weeds are a major factor behind the THREE-fold increase in annual per acre use of glyphosate in cotton, and double the rate on soybeans, since introduction of RR versions of these crops, according to gold standard USDA NASS data on pesticide use (which data, incidentally, are ignored by industry flacks like PG Economics and NCFAP).

Furthermore, for those in ignorance or denial, glyphosate-resistant weeds are having two other effects, also discussed in the report: 1) Increased use of other herbicides like 2,4-D on soybeans; and 2) A plethora of new HT crops engineered for tolerance to higher levels of glyphosate and/or tolerance to multiple herbicides, including nasty chlorophenoxy herbicides like dicamba and 2,4-D (see Chapter 7 for documented discussion). In other words, the glyphosate-resistant weeds fostered by RR crop systems are deeply shaping the industry's product pipeline. The report cites a patent issued to DuPont-Pioneer claiming a single plant resistant to anywhere from two to seven or more different herbicides. For those truly concerned with toxicity of pesticides (e.g. Karl Haro von Mogel's comment on EIQ), these increasingly toxic responses to the rapidly degrading efficacy of glyphosate (over less than a single decade) should be of major concern, as should the strong and growing evidence of the greater toxicity of Roundup formulations with certain surfactants (e.g. POEA) vs. glyphosate alone.

A look at the evidence shows that this is the true future of agricultural biotechnology - more pesticide-promoting HT crops - rather than the attractive-sounding posterchild crops (the ones endlessly touted in the press that never do come to market, somehow!) so often cited by biased commentators. The fact that the pesticide manufacturers which are also the biotechnology companies focus their R&D efforts on HT crops should hardly come as a surprise. And when the pesticide-biotech firm doesn't produce the HT crop-associated herbicide, a joint venture works nicely to share the benefits - for instance, Monsanto-BASF collaborating on dicamba-resistant soybeans (BASF is the major producer of dicamba) - once again, documented in the report.

A few more technical comments. The report does in fact discuss non-GE HT crops, including: 1) That they are planted on roughly 6 million acres, or only <5% of acreage planted to GE Roundup Ready, and are almost all resistant to ALS inhibitors; 2) That the prevalence of weeds resistant to ALS inhibitors (which include imidazolinones) has greatly limited the usefulness and acreage planted to these non-GE HT crops (e.g. Clearfield, STS soybeans); and 3) That one important factor driving adoption of Roundup Ready crops was the prevalence of ALS inhibitor-resistant weeds (notably, common waterhemp in the Midwest, but many many others). This points up nicely the pesticide-treadmill effect of HT crops, whether GE or not. Weed scientists are increasingly concerned by the emergence of multiple herbicide-resistant weeds.