Superweeds on the March?

Opponents of genetically engineered crops have used the tendency of genes to spread from the engineered plants to their wild cousins as a major argument against widespread planting of biotech crops. A new study shows that, at least in one case, their concerns may be legitimate.

The study, done by scientists with the Environmental Protection Agency, found that a genetically engineered grass designed for use on golf courses pollinated test plants of the same species as far away as 13 miles downwind, the New York Times reports. Naturally occurring wild grass of a different species was pollinated by the GE grass nearly nine miles away.

The GE grass, known as creeping bentgrass, was developed by Monsanto and Scotts to be resistant to the herbicide Roundup. The altered plants would allow groundskeepers to use the spray to kill weeds on their greens and fairways without harming the grass. The Times quotes Norman C. Ellstrand, an expert at the University of California, Riverside, who was not involved in the study: “The gene really is essentially going to get out…What this study shows is it’s going to get out a lot faster and a lot further than people anticipated.”

The concern is that the spread of the herbicide-resistance gene to wild grasses could lead to “superweeds” that couldn’t be killed with existing weed sprays, in particular the popular RoundUp spray.

It’s worth noting that the GE grass raises issues that differ from those surrounding existing GE crops such as corn and soybeans. Specifically,

1)the grass is perennial, while GE crops are planted anew every year, making them easier to control. Such crops also rarely survive without the tending they receive on a farm, while grass can easily survive in the wild.

2)bentgrass can cross-pollinate with at least 12 other species of grass, while existing GE crops, except for canola, have no wild relatives where they are grown in the United States.

3)bentgrass has very light pollen that can travel great distances and also has very light seeds that disperse readily in the wind, making it more likely that the GE plants could spread on their own–expanding the area over which they could spread pollen–and the modified gene.

The upshot for me? Bentgrass may turn out to be the embodiment of GE opponents’ fears. But each new GE plant needs to be carefully assessed on its own merits and dangers, rather than assuming because one plant carried exceptional risks–or was safe enough to plant–all will. Few things in life are all good or all bad, whatever the proponents or opponents say. Genetically engineering plants is no exception.