OREGON CITY, Ore. >> An Oregon grower is giving its Christmas trees a hot bath before shipping to make sure buyers don’t get slugs and yellow jackets as unexpected presents.

The Kirk Co. of Oregon City sends harvested trees on conveyer belts through an enclosed washer to kill or knock off pests, the agricultural publication Capital Press reported Tuesday.

"What you’re trying to do with that is control hitchhikers," said Bob Bishop, a trade specialist with the federal Animal and Plant Health Inspection Service.

The trees also get moisturized and stay fresh and green longer, he said.

It’s the second year the company has tried the experiment that’s drawing attention from foreign agricultural officials and other Oregon growers who are less likely than Kirk to have the water or electrical capacity to bathe trees.

"Growers in general hope it doesn’t come to this," said Chal Landgren, a Christmas tree specialist with Oregon State University Extension Service.

Oregon leads the nation in Christmas tree production with about 7 million trees sold in 2013, or 17 percent of the U.S. total, according to federal statistics. The crop is worth more than $100 million a year.

Agriculture officials from the Philippines and Malaysia observed the washing process on Monday.

Kirk co-owner Gary Snyder said the Hawaiian market is his biggest concern. Inspectors in the state are leery of invasive species and require fumigation if bugs are discovered in a load of trees.

"I’m shipping 75 to 80 containers to Hawaii," Snyder said. "If less than five of them get held up for slugs, I’ll feel successful."

Kirk Co. ships about 500,000 trees a year and has operations in Oregon, Washington, North Carolina and Nova Scotia.