GRANTS PASS, Ore. » Oregon farmers are moving ahead with plans to start planting their next crop as questions remain about the source of a patch of genetically modified wheat found in a farmer’s field there last spring that threatened trade between the Pacific Northwest and other countries.

Speculation about the origin of the unapproved wheat discovered in northeastern Oregon ranges from saboteurs to a passing flock of geese. The U.S Department of Agriculture’s Animal and Plant Health Inspection Service said Friday their investigation is ongoing.

Grass Valley wheat farmer Darren Padget says they may never know for sure, but he and other farmers are going ahead with plans to start planting winter wheat in mid-September.

"It’s one of those things where you just scratch your head," the Oregon Wheat Commission member said as he loaded another truck with seed wheat to haul to a supplier for the local farmers’ co-op. "Everybody’s talking about seeding. We had rains through here the other day that will make seeding conditions good."

Blake Rowe, the commission’s CEO, said although Asian buyers stopped placing orders for a couple of months, the overall economic impact has been minimal, and markets are back to normal.

Japan, South Korea and Taiwan all resumed placing orders for Northwest wheat after tests failed to turn up any that was genetically modified.

The Japanese government tested 1.2 million metric tons of U.S. wheat for GMO material without finding any, according to the trade group U.S. Wheat Associates.

"The customers came back before the harvest was really finished," Rowe said from his Portland office. "It didn’t really interfere too much with the movement of wheat."

If there is any more genetically modified wheat growing, farmers won’t know until spring.

Fields that grow wheat this winter will be sprayed with herbicides after harvest in the spring, so they can lie fallow for a year. Any wheat growing after it has been sprayed is likely to have been genetically modified to survive herbicides, which makes it easier to grow.

That’s how the rogue strain was discovered. The farmer sent a sample to Oregon State University, where it was determined to be genetically modified. USDA confirmed the finding.

Though USDA says the grain is safe to eat, it has not been approved for growing in the U.S. Japan and Korean won’t buy genetically modified wheat, so they stopped placing new orders, though shipments on existing contract were not stopped, Padget said.

Oregon farmers typically produce 50 million bushels of wheat in a year, said Rowe, and as much as 90 percent of that goes for export, primarily to Asia. Due to drought and frost issues, this year’s harvest likely will be less, though the final numbers are not in, he said.

"We haven’t heard of any growers changing what they do," Rowe said. "And we have not heard from any customers who said they are not going to use soft white" wheat, for which there is no real substitute.

Padget said things could have been a lot worse. He’s glad the farmer, who has not been identified, did the right thing and notified authorities, rather than plowing the genetically modified wheat into the ground and keeping his mouth shut.

"Everybody’s a little more vigilant now than they were before," Padget said.