A herbicide-resistant strain of charlock has been found growing in a GM oilseed rape field. Hybrids between the two species were previously thought unlikely, and it is not clear exactly how gene transfer occurred. Superweeds are an increasing problem in Canada. Defra report - Guardian - Scotsman - New Scientist.

http://www.guardian.co.uk/uk_news/story/0,3604,1535363,00.html