The Christmas tree tradition supports a sizeable industry in Washington, and Gary Chastagner, a scientist at the Puyallup Research and Extension Center, works to make sure both tradition and industry remain strong.

Sudden oak death, an exotic plant disease with the potential to kill some species of large oak trees, is Chastagner’s main concern.

“At least 40 percent of the nation’s Christmas trees are produced in Washington state, and half of them are Douglas firs,” he said.

While sudden oak death does not kill Douglas firs, the trees do make a viable host of for the disease. If the trees were infected and then sold across the country, they could infect other trees that could die from the disease.

So far, the disease has been found only in urban forest settings in California and in a small area of southwestern Oregon. If left unchallenged, however, sudden oak death has the potential to cause cankers and even kill many large trees.

The disease is debilitating economically as well as ecologically. Last year, a couple of larger nurseries were found to have shipped infected trees to 22 states. Through the trace-forward system that accesses the customer list of the nurseries the trees were tracked down and destroyed. Unfortunately, the nurseries were unable to sell any plant material until extensive tests were done during the next 90 days.

Sudden oak death could be especially catastrophic to the Christmas tree industry.

“For example, if the pathogen was found at a nursery in early November in Pierce County, all nurseries within the county would be quarantined for 90 days and would not be able to sell anything until that time period was up,” Chastagner said. “These nurseries would miss the Christmas season altogether.”

Chastagner encouraged Washington state consumers not to worry, however, when picking out their tree this year. “Most growers in Washington have had voluntary inspections done to ensure the trees are healthy.”

For more information on sudden oak death and other projects at the Puyallup Research and Extension Center, visit the website at http://www.puyallup.wsu.edu.