GM crops not likely to become 'super-weeds'

A long-term study shows the four GM crops tested are not more invasive or more persistent than their non-GM counterparts.

By | February 14, 2001

The results of a long-term study reported in the 8 February Nature might allay fears that genetically modified (GM) crops, once released into the environment, could invade and dominate other habitats or cross-pollinate with non-crop plants.

Following a 10-year survey of four GM crops, Michael Crawley and colleagues, from Imperial College, London report that the particular GM crops studied did not survive well in the wild, and were not more likely to invade other habitats than their non-GM counterparts (Nature 2001, 409:682-683).

In 1990, fields located at 12 different sites in the UK, were planted with the GM crops available at the time — rape, maize, sugar beet and potato, each engineered to express resistance to herbicides or insects — alongside non-GM versions of the same crops. In no case was a GM crop found to be more invasive or persistent than its non-GM counterpart. Within four years, all crops — GM and non-GM — died naturally. At only one site were survivors found a decade later, and all of these were non-GM.

Crawley and his colleagues stress that their study does not vindicate all GM crops. New varieties that are engineered to tolerate drought, for instance, could show increased survival, and their ecological impact will need to be tested as they are developed.

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