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Re: [SANET-MG] Bt cotton does not imporve yield



Hi Steve,
You have certainly clarified that matter :-) It had never before occurred to me that two plus two makes six. sincerely,joe
Steve Ford wrote:
Joe,
But the remainder of the sentence you highlight states, "...largely
because higher insecticide use with nontransgenic cotton improved
control of key pests."  So, is it the nontransgenic cotton or the
insecticides that caused equivalent yields?  In fact, the sentence
preceding that which you highlight states, "Transgenic cotton had higher
yield than nontransgenic cotton for any given number of insecticide
applications." which implies to me that if you control for the
confounding factor in the sentence you highlight and I finish for you,
then transgenic cotton does yield more.


This is stated again in the following article
http://www.sciencedaily.com/releases/2006/05/060501232015.htm .

"The researchers found that, per pesticide application, Bt cotton
produced 9 percent more cotton/acre than non-Bt cotton. However, growers
that planted Bt cotton used fewer applications of broad-spectrum
insecticides.

As a result, growers ended up with similar yields/acre regardless of the
type of cotton grown. Carrière suggests that yields were similar across
cotton types because the additional insecticide applications on the
non-Bt fields cut down on the damage from whiteflies and western
tarnished plant bugs."

This is important information for those of us who produce cotton.  I'll
look for the original scientific article.  Thanks for the citation.

Steve


-----Original Message-----
From: Sustainable Agriculture Network Discussion Group
[mailto:SANET-MG@LISTS.IFAS.UFL.EDU] On Behalf Of jcummins
Sent: Thursday, May 04, 2006 1:44 PM
To: SANET-MG@LISTS.IFAS.UFL.EDU
Subject: Re: [SANET-MG] Bt cotton does not imporve yield


Hi Steve,
The point is "However, nontransgenic, Bt and BtHr cotton had similar yields overall" it seems to me that says Bt cotton does not improve yield over conventional cultivation, as you are aware there were no organic cotton crops in the comparison. The original paper is open and available to all. It would take supernatural word engineering to convert

the study into public relations for Monsanto.However, that will certainly not dissuade the Monsanto zealots from trying. sincerely,joe
Steve Ford wrote:
Joe,
I've tried several times, but in reading the abstract below I can't come to the same conclusion you did in the subject line. Perhaps you could explain your thoughts on this. Thanks. Steve Ford

-----Original Message-----
From: Sustainable Agriculture Network Discussion Group [mailto:SANET-MG@LISTS.IFAS.UFL.EDU] On Behalf Of jcummins
Sent: Thursday, May 04, 2006 11:43 AM
To: SANET-MG@LISTS.IFAS.UFL.EDU
Subject: [SANET-MG] Bt cotton does not imporve yield


In the article below Bt is Cry1Ac for pink boll worm control and BtHr

is Bt roundup ready cotton.
Published online before print May 4, 2006
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0508312103

Agricultural Sciences
Farm-scale evaluation of the impacts of transgenic cotton on
biodiversity, pesticide use, and yield
( agricultural sustainability | environmental impact | transgenic
crops
)

Manda G. Cattaneo *, Christine Yafuso *, Chris Schmidt *, Cho-ying Huang

, Magfurar Rahman , Carl Olson *, Christa Ellers-Kirk *, Barron J. Orr

,

Stuart E. Marsh , Larry Antilla , Pierre Dutilleul ¶, and Yves Carrière *||

Higher yields and reduced pesticide impacts are needed to mitigate the
effects of agricultural intensification. A 2-year farm-scale
evaluation
of 81 commercial fields in Arizona show that use of transgenic
Bacillus
thuringiensis (Bt) cotton reduced insecticide use, whereas transgenic cotton with Bt protein and herbicide resistance (BtHr) did not affect herbicide use. Transgenic cotton had higher yield than nontransgenic cotton for any given number of insecticide applications. However, nontransgenic, Bt and BtHr cotton had similar yields overall, largely because higher insecticide use with nontransgenic cotton improved control of key pests. Unlike Bt and BtHr cotton, insecticides reduced the diversity of nontarget insects. Several other agronomic and ecological factors also affected biodiversity. Nevertheless, pairwise comparisons of diversity of nontarget insects in cotton fields with diversity in adjacent noncultivated sites revealed similar effects of cultivation of transgenic and nontransgenic cotton on biodiversity.
The
results indicate that impacts of agricultural intensification can be reduced when replacement of broad-spectrum insecticides by narrow-spectrum Bt crops does not reduce control of pests not affected

by Bt crops.

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