The sprouting of an unapproved genetically engineered wheat strain in an Oregon field appears to have been an isolated incident, U.S. agricultural officials said on Friday, adding that they had validated a method for detecting the presence of the GE wheat.

"As of today, USDA has neither found nor been informed of anything that would indicate that this incident amounts to more than a single isolated incident in a single field on a single farm," said USDA Office of Communications Director Matt Paul. "All information collected so far shows no indication of the presence of GE wheat in commerce."

Investigators are conducting a "thorough" review of the situation and are continuing to interview approximately 200 area growers, Paul said. USDA has interviewed the producer that harvested the GM wheat as well as the supplier who sold him the wheat seed and has obtained samples of the seed sold to that producer and to others. Samples of the producer’s wheat harvests have also been obtained, including his 2012 harvest. All of the seed and grain samples tested negative for the presence of GE material, Paul said.

The Capital Press newspaper in Oregon reported last Wednesday that USDA took samples from a seed company in Walla Walla, Washington, and from some of the company's customers.

On June 13, 2013, USDA validated an event-specific DNA-based method for detecting the GE wheat strain – MON71800 – a glyphosate-resistant strain developed by Monsanto Co. USDA determined the method can reliably detect MON71800 when it is present at a frequency of 1 in 200 kernels. "Additionally, USDA has provided this validated DNA test method to detect this specific GE variety to our trading partners that have requested it," Paul said.

Major markets, such as Japan, Korea and Taiwan, have postponed imports of U.S. white wheat as they continue to study information from U.S. officials to determine what, if any, future action may be required.

South Korean buyers continue to avoid any new purchases of U.S. wheat. South Korea’s largest feed maker Nonghyup Feed Inc. excluded U.S. wheat from a tender it issued on Monday for feed wheat. Japan also has excluded U.S. feed wheat from the Pacific Northwest from its feed wheat tenders.

Editor’s note: Richard Brock, Corn & Soybean Digest's marketing editor, is president of Brock Associates, a farm market advisory firm, and publisher of The Brock Report.