Don Cameron, a farmer in California, recently posted a response which addresses your question regarding crop contamination. Included below is an excerpt from the response which you may find interesting.
“If GMO traits are found in the organic farmers crop, it is usually up to the buyer of the crop to accept or reject his product based on their contract specifications which does allow for a certain percentage of GMO traits to be present. Organic certification does not equal zero presence of a GMO trait. Low-level presence of a GMO trait in organic production is allowed as long as the grower has followed the organic process necessary for organic production.”
To view Cameron’s response, click here: http://gmoanswers.com/ask/if-i-am-organic-farmer-and-gmo-technology-contaminates-my-crops-do-i-have-any-recourse-how-do-i.
If you feel that your question has not been answered in this response, or if you have additional questions, please ask here: http://gmoanswers.com/ask-your-question.