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How Genetically Modified Crops Could Affect Weeds


After unauthorized, genetically modified wheat was found in an Oregon field, scientists have been trying to figure out what that means for wheat crops. Beyond farmers’ fields, a few pesky plants could also benefit as more genetically modified crops come into play.

An invasive weed called jointed goatgrass mingles with wheat in fields across the Northwest – and throughout the United States.

Carol Mallory-Smith has studied wheat and jointed goatgrass at Oregon State University for years.

“Goatgrass came from the same area of the world where wheat came from, which would have been in the Fertile Crescent," Mallroy-Smith says.

Jointed goatgrass made the journey from the Middle East to the United States in the late 1800s. The weeds have spread even more in the last 50 years.

Jointed goatgrass competes with wheat for water, light and nutrients. In the worst cases, jointed goatgrass significantly reduce how much wheat farmers can grow.

There are no known herbicide-free alternatives to killing jointed goatgrass -- although it helps when farmers till their land less.

If wheat and jointed goatgrass are in close enough proximity, they can share pollen. The resulting seeds are a hybrid of the two plants. Scientists refer to this as cross-pollination.

So, what if wheat is genetically modified -- like what was found in Oregon? Cross-pollination would make weeds resistant to herbicide.

OSU researcher Mallory-Smith says it’s unlikely that happened in Oregon. That’s because only one percent of an Oregon farmer’s field was found to have GM wheat. She says the same wouldn’t be true for an entire GM field.

“If you had a field of genetically modified wheat and goatgrass was in it, then, yes, you could expect gene flow to occur," says Mallory-Smith.

This ‘gene flow’ from GM cotton in the South has transferred to weeds, making them able to survive in fields sprayed with Roundup. No other significant cross-pollination has happened yet. That’s according to a report for the National Research Council.

Portland State University professor David Ervin was a lead author on the report. He says that doesn’t mean genes won’t transfer from farmed plants to wild ones.

“We should really make sure that we’re very careful and cautious about how we make these decisions, so that we don’t have an episode that leads to serious gene flow problems that are difficult to control," he says.

Ervin says harsher chemicals and cultivation practices will be needed to control some invasive plants if they become resistant to herbicides. That can lead to more water pollution and soil erosion, and more carbon being released into the atmosphere.

Copyright 2013 EarthFix

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