The potato disease is not harmful to humans, but it causes flecking in potatoes' flesh, and when they are fried, the chip darkens. The defect can make the potatoes undesirable.
Gregoire, talking to reporters by phone from South Korea, said the ban on potatoes grown in Washington state, Oregon and Idaho was lifted this week. South Korea put the ban in place in August.
The first shipments of potatoes should be leaving Sunday, officials said.
Matt Harris, with the Washington Potato Commission, said that as part of the agreement, Washington state will apply a sprout inhibitor and will also cut into a set amount of tubers to look for signs of the pest.
Harris said Washington state produces roughly 9 billion pounds of potatoes annually, of which 87 percent is used for the processing industry: french fries, dehydrated potatoes and potato chips.
French fries and dehydrated potatoes were never subject to the ban, he said.
An estimated 20,000 metric tons of potato chip potatoes were contracted to be sent to South Korea, Harris said.
"We're thankful that the Korean government and U.S. government were able to sit down and talk about mitigation tools to make sure trade stays fluid," he said.
Harris said the market on fresh potatoes is still closed, but there are continuing efforts to find a solution. There are about 3,000 metric tons of fresh potatoes from the three Pacific Northwest states that are still held up while those talks continue.
Harris said that the lifting of the ban clears the way for more than $5 million in exports between now and the end of the year.
Gregoire called the lifting of the ban "a significant breakthrough for our potato growers."
"This was one of many issues that we intended to bring up with our government counterparts in South Korea, and I'm pleased it could be resolved while our delegation was here," Gregoire said in a written statement. "This serves as a strong example of the importance of good relationships with our trading partners."
Gregoire will be back in Washington state Thursday. Her 10-day trade mission also included stops in India.