Pest Threatens to Take a Huge Bite Out of the Christmas Tree Industry : Environment: The pine shoot beetle’s invasion of North America has sparked several quarantines. Growers fear the worst is to come.

An immigrant beetle with a taste for Scotch pines has taken the joy out of the holidays for many Christmas tree growers and eventually may threaten all of North America’s pine forests.

Christmas tree buyers aren’t expected to see higher prices or tree shortages this year, according to industry spokesmen.

But the U.S. Agriculture Department estimates that the pine shoot beetle will cost American businesses and taxpayers nearly $900 million in damage to tree crops, landscape trees and standing timber over the next 30 years.

“No question, it will do very, very well in North America,” said Robert Haack, an entomologist with the U.S. Forest Service. “We could build up some large numbers quite rapidly. The beetle has the potential to do a lot of damage here.”

The Christmas tree business could greatly speed the process. The seasonal movement of more than 35 million freshly cut trees could spread the pest all over the North American continent. Stumps left after the harvest provide ideal breeding spots.

That’s the reasoning behind the quarantines established last year in the United States and Canada that prohibit shipment of infected trees outside the county where they are grown.

Quarantines of farms have been extended to twice as many counties as last year in the two countries, but foresters say this will only slow, not stop, the beetle’s inevitable spread to natural woodlands.

Six states--New York, Pennsylvania, Ohio, Indiana, Illinois and Michigan--and Canada’s Ontario province have quarantines this year.

Standards are strict. Agricultural inspectors in both countries check each Christmas tree grove in November, just before harvest. Every tree is inspected for any sign of the beetle. All trees from an infected grove are restricted.

“One beetle can literally shut you down,” said Gary Reissen, owner of a 1,700-acre Christmas tree farm in Greenville, Mich.

The shiny, dark, cylindrical insect, no larger than a match head, is a recent invader from Europe and Asia. It has swept through Christmas tree farms around the Great Lakes region since it was discovered last year in Ohio.

Preliminary studies show that it will thrive on any of North America’s 35 pine species, although it prefers the Scotch pine--the favorite Christmas tree--which is plentiful on tree farms and in forests.

Pine shoot beetles weaken trees in several ways. New shoots die shortly after a single beetle enters to feed on the soft pulp inside. Heavily infested trees lose shape and eventually become susceptible to deadlier diseases. Long-term infestations in Europe have reduced the size of pines by as much as 40%.

The beetle has been a problem for decades throughout European and Asian forests, where timbering is regulated to keep the pest in check.

No one knows how the insect entered North America. Some scientists say they believe that it came in on lumber used to brace cargo shipped to Great Lakes ports.

Hasty research, begun last year by the Forest Service after the beetle was discovered, suggests that the insect eventually will have a heyday in North America.

Nobody can predict how fast it will spread. Scientists are studying possible ways to control it and hope to make recommendations next year.

Meanwhile, the beetle will find plenty to eat almost anywhere in North America. The insect has no natural enemies in this part of the world. Entomologists predict and fear that it will spread as far north as Alaska and as far south as Mexico.

It is likely to benefit from the North American practice of harvesting timber year-round.

In natural conditions, pine shoot beetle infestations spread slowly, allowing biological controls--mainly small wasps--to develop. The beetle travels only short distances and breeds just once a year. New colonies start only in freshly opened wood, such as storm-damaged branches, lightning-fractured trunks and chain-sawed stumps.

Reissen is one of the Christmas tree growers who considers himself lucky this year. He carefully pruned each tree throughout the growing season, eliminating any shoot that showed the tiniest sign of a beetle among his 170,000 harvest-ready trees.

“It was a lot of work,” he said, “but consider the alternative. It’s not just a one-year type of thing. If all of a sudden you can’t fill an order, do you think they’ll order from you again next year? I don’t think so.”

As it turned out, only 1% of Reissen’s stock, in one field, was infested. Some of his friends in the business didn’t fare so well.

Reissen and other growers worry more about the quarantines than about the pine shoot beetle itself. Most Christmas trees are cut before beetles can damage them aesthetically. Quarantines cost growers money in trees they’re forbidden to sell.

The growers grudgingly support quarantines as a courtesy to their sister industries, whose trees are older and therefore more subject to deformity or death.

“This little beetle is a much bigger threat to the timber and nursery industries,” said Joan Geiger, executive director of the Milwaukee-based National Christmas Tree Assn. “We’re just trying to help control it.”

The biggest fear among Christmas tree growers is losing customers, who mistakenly may assume that the beetle is a threat to themselves or their homes and then switch to an artificial tree. Already, artificial trees are almost as popular as natural ones.

“You’re not going to get sick. It can’t eat your house,” Geiger said. “We just hope it doesn’t destroy the industry.”

No one knows what becomes of dormant beetles in Christmas trees. “We don’t know whether they die from the heat, drown in the stand or survive to infest other trees,” Haack said.

To find out, he and a team of Michigan technicians will monitor 12 infested Christmas trees during the coming holidays.