|Wheat field in Oregon, USA: Photo Creative Commons|
As of August 2016, we can tentatively answer that question: one per year.
A year after the Oregon contamination incident, it was Montana's turn. Some thousand GM wheat plants were found growing in a Montana State University crop research field. That was eleven years after the last GM wheat field trial there.
A year after the Montana contamination incident, it was Washington State's turn. Twenty two plants have been found growing in a farm there. This variety of GM wheat was trialled in the Pacific Northwest (Washington State and Oregon) from 1998 to 2000, suggesting it has re-surfaced after 16 years. Tests indicate it is a different strain from the GM wheat found in Oregon, and no one's mentioning any possible links to the Montana State University incident.
Industry and wheat growers representatives declared the first rogue GM wheat "impossible", in fact "so improbable that this has got to be a bad test", and dismissed it as an "isolated event".
However, it seems to have been none of these things. So what's gone wrong?
The US regulators don't know. No one from the Federal government inspected the test fields during the trials nor subsequently to make sure the experimental plants had been properly destroyed.
US Department of Agriculture investigators in Montana State University focused on the research facility's machinery and whether it might have dredged up buried GM wheat which it then tracked across the university fields. Their main concern seemed to be that the equipment might not have been properly cleaned. Since wheat seeds can lie dormant in the soil for eleven years or more, they theorised that old wheat could have suddenly sprouted when it was disturbed.
However, the superintendent of Montana State University’s research centres has pointed out that the GM wheat was growing mostly beneath an overhead powerline. Whole-wheat grains aren't very digestible. Droppings from the pigeons frequenting the powerline after eating GM wheat from some other, unidentified, gene-polluted site is a much simpler explanation.
All this GM wheat was transformed to be glyphosate-tolerant (Roundup Ready): it will only become obvious if it's growing in a field treated with the herbicide to clear the weeds. GM wheat with other traits or in locations not sprayed with glyphosate will carry on growing, carry on spreading GM pollen to other wheat nearby, carry on being eaten by pigeons, and carry on growing in unexpected places.
Despite this, and other obvious animal-borne routes to GM wheat spread, the US Department of Agriculture doesn't have a protocol to evaluate that risk "Therefore it doesn't exist."
Despite the 2006 undertaking to discontinue commercial GM wheat development, Monsanto is still reported to be carrying out tests in North Dakota. New experimental traits might well be routinely linked to a herbicide-tolerance gene as a technical aid to the selection of successful transformants.
Take your pick. Is the rogue GM wheat popping up from decades-old spillage (which shouldn't happen in a research facility) after it has been accidentally uncovered and shifted to a new location by dirty machinery (which shouldn't happen in a research facility)? Or, did the GM wheat sprout from nice, fresh, grains borne by GM wheat growing away quietly somewhere in the countryside on which a pigeon has been stuffing its face before resting on a powerline to let its digestive nature take its course?
GM contamination is easily identified in the case of the glyphosate-tolerant varieties trialled in America. However in the UK, Rothamstead Research's aphid-repellant wheat (no doubt still under development despite the disappointing trials published in 2015) will rampage across the countryside by pigeon-post. Do we need a long-term rolling programme of routine testing for the presence of GM wheat, despite the fact it's not been commercialised anywhere in the world and despite the fact that wheat growers have asked that it should not be developed? It sure looks like it.
 CONTAMINATION DÉJÀ VU - June 2013
- Karl Plume, USDA confirms unapproved GMO wheat found in Washington state, Reuters, 29.06.16
- P. J. Huffstutter, Japan, South Korea block certain U.S. wheat varieties over GMO concerns: USDA, Reuters 1.08.16
- Tom Lutey, The accidental release of forbidden GMO wheat in Huntley could have been catastrophic, Billings Gazette, 28.8.16