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|    | Gene stacking could lead to more weeds (Feb. 6, 2002 – CropChoice news) – A study that English Nature commissioned found that different varieties of oilseed rape genetically modified to resist herbicides cross-pollinated with one another and, in the process, gained resistance to several herbicides.  With these "stacked" resistant genes, they’ve turned into nuisance weeds. 
The complete study is available at  http://www.checkbiotech.org/pdf/englishnaturegenestacking.pdf. 
Related CropChoice story: http://www.cropchoice.com/leadstry.asp?recid=563 
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