Superweed

Guardian Unlimited | Special reports | GM crops created superweed, say scientists
www.guardian.co.uk/gmdebate/ Story/0,2763,1535428,00.html
Modified rape crosses with wild plant to create tough pesticide-resistant strain
Paul Brown, environment correspondent
Monday July 25, 2005
The Guardian
[Extracts from the article - I recommend a full read, there are some good links on end of the page too.]

Modified genes from crops in a GM crop trial have transferred into local wild plants, creating a form of herbicide-resistant 'superweed', the Guardian can reveal.
It was found during a follow up to the government's three-year trials of GM crops which ended two years ago.

The new form of charlock was growing among many others in a field which had been used to grow GM rape. When scientists treated it with lethal herbicide it showed no ill-effects.
Unlike the results of the original trials, which were the subject of large-scale press briefings from scientists, the discovery of hybrid plants that could cause a serious problem to farmers has not been announced.

The scientists also collected seeds from other weeds in the oilseed rape field and grew them in the laboratory. They found that two wild turnips were herbicide resistant.
Dr Brian Johnson, who is head of the biotechnology advisory unit and head of the land management technologies group at English Nature, the government nature advisers, said: "Unlike the researchers I am not surprised by this. If you apply herbicide to plants which is lethal, eventually a resistant survivor will turn up."

The glufosinate-ammonium herbicide used in this case put "huge selective pressure likely to cause rapid evolution of resistance".

To assess the potential of herbicide-resistant weeds as a danger to crops, a French researcher placed a single triazine-resistant weed, known as fat hen, in maize fields where atrazine was being used to control weeds. After four years the plants had multiplied to an average of 103,000 plants,

Since charlock seeds can remain in the soil for 20 to 30 years before they germinate, once GM plants have produced seeds it would be almost impossible to eliminate them.

The findings mirror the Canadian experience with GM crops, which has seen farmers and the environment plagued with severe problems.
The new plants were dubbed superweeds because they proved resistant to three herbicides while the crops they were growing among had been genetically engineered to be resistant to only one.

To stop their farm crops being overwhelmed with superweeds, farmers had to resort to using older, much stronger varieties of "dirty" herbicide long since outlawed

Farmers in Canada and Argentina growing GM soya beans have large problems with herbicide-resistant weeds. Experiments in Germany have shown sugar beets genetically modified to resist one herbicide accidentally acquired the genes to resist another - so called "gene stacking", which has also been observed in oilseed rape grown in Canada.

Telegraph | News | GM superweed discovered
(Filed: 25/07/2005)

The first genetically modified superweed has been discovered in the UK according to Government research.

The plant, which is resistant to some types of weed killer, is the result of GM oilseed rape cross-breeding with a common weed in farm scale trials.