GE crops radically change the nature of farming, transferring control of seed from farmers to agrochemical companies such as Monsanto. Contamination from GE crops also threatens the integrity of traditional farming crops and affects access to markets.

Seed for GE crops is owned by agrochemical companies under patent law. This enables them to set conditions on farmers using the seed — for example, requiring farmers to pay royalties or demanding that farmers purchase new seed each season rather than sowing seed saved from previous harvests. GE crops bind farmers into legally enforceable, restrictive and onerous agreements.

In Canada and the United States, where GE crops have been sowed for over 12 years now, these companies aggressively pursue legal action against farmers for patent infringement. Many of these are farmers unknowingly growing GE crops on their land as a result of contamination. Canadian canola grower, Percy Schmeiser, was sued by Monsanto because GE canola was growing on his land as a result of contamination. Monsanto successfully argued patent infringement.

There is also a much larger economic cost for farmers across the board.

Again in North America, conventional growers are discovering that GE crops from neighbouring fields have become weeds that cannot be sprayed off with herbicides because they have inbuilt resistance. The Royal Society of Canada has warned that most of the country's prairie land is now contaminated with herbicide-resistant canola weeds, the removal of which raises farm costs.

US and Canadian farmers are discovering a further problem with GE crops —export markets won’t buy them. Following the introduction of GE canola in Canada, sales to Europe dried up. The same is true of US corn, which is no longer sold to Europe.