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Wednesday 2 April 2008

RAPID ROUNDUP: Long term persistence of GM canola in the environment (Biology Letters) – experts respond.

How well GM canola can be separated from conventional varieties is a key issue following the lifting of the GM moratorium in NSW and Victoria. An important aspect of this issue is how long GM canola will persist in the environment after the GM crop is removed. New research to be published in the Royal Society journal Biology Letters provides evidence that herbicide tolerant GM canola can persist for considerable time in agricultural fields. Ten years after a GM field trial in Sweden, herbicide tolerant seedlings were detected and confirmed positive for GM inserts. The AusSMC has rounded up Australian experts to comment on this research

Feel free to use these comments in your stories. If you would like to speak to one of these or other experts, please don’t hesitate to contact us on (08) 8207 7415 or by email.

Dr Christopher Preston is a Programme Leader for the CRC for Weed Management and Head of the Discipline Plant & Food Science in the School of Agriculture at the University of Adelaide.

“Farming systems can be quite different in Europe compared to Australia. In Europe, deep cultivation is often practiced, which will bury canola seed and induce secondary dormancy. The seed will not germinate until exposed again by another tillage operation. In Australia, most farmers practice minimum tillage, with shallow cultivation, or no-till with no cultivation. In these systems, canola seed is left on the soil surface for longer and either germinates, is eaten by ants or decays.

Recent surveys of farm canola seed banks in South Australia have shown the seed banks decay rapidly and are almost extinct by 3.5 years after harvest. The seed remaining in the seed bank 2.5 years after harvest are mostly unable to germinate. Farmers in Australia can manage canola seed banks easily by ensuring no deep tillage and no tillage over the summer months in order to leave the seed on the surface.”

Dr Peter Vesk is a Lecturer with expertise in ecological management at the University of Melbourne’s School of Botany.

“This work along with other studies of GM- oilseed rape (canola) indicates the likely persistence of GM seed for over 10 yrs after a single GM crop. While much of the decline in soil-stored seed happens in the first year or two, some seeds last for a good deal longer.

The question is how many seeds persist to different times? I don’t know of any longer study than this. As more studies are done, longer persistence times will certainly be reported. But predictions of the actual number of seeds left after long times are highly uncertain. It will come down to what risk of GM-contamination people are prepared to bare.”

Professor Mark Westoby is a plant ecologist in the Department of Biological Science at Macquarie University.

"This study confirms that GM crops are difficult to confine. Like any life-form, they have potential to disperse across space or (as in this case) through time. Although the great majority of seeds produced were killed by harvesting or by good management through the ensuing decade, the small percentage surviving after ten years still amounted to about 100 GM seedlings per hectare."

"We should assume that GM organisms cannot be confined, and ask instead what will become of them when they escape, or when the genes they contain escape to wild relatives. In the particular case of GM herbicide-tolerance, there is no reason why it should have competitive advantage anywhere except where herbicides are being used. So its escape is a potential problem for crop production but not for natural ecosystems."