If you have a real Christmas tree, University of California pest management experts ask that you to recycle the tree to prevent the spread of insects and diseases that may harm our forests and landscape trees.

“Invasive insects, diseases and plant seeds can move on cut Christmas trees and other holiday greenery,” said Janice Alexander, UC Cooperative Extension forest health educator in Marin County. “These pests can escape out into backyards and neighboring forests to begin new populations, upsetting the balance of our native ecosystems. Proper purchasing and disposal of holiday greenery helps reduce that risk.”

Alexander recommends taking advantage of local tree recycling programs.

“Many municipalities and service organizations offer this service right at your curb,” she said. “If you aren't able to find or use this option, take the tree to your local solid waste facility, dump or landfill. This will keep any pests that might be in the tree from spreading and the landfill uses the material as cover.”

“You should not try to burn the wood indoors as fresh sap can create fire hazards,” she added, “and don't set the tree out in a backyard brush pile where pests and weed seeds could escape onto your property.”

“The most worrisome pests that might be traveling on Christmas trees or greenery this year include P. ramorum, pine shoot beetle and gypsy moth,” Alexander said.

The movement of some fresh trees is regulated. For example, Douglas fir trees are regulated because they are hosts for Phytophthora ramorum, which causes sudden oak death. The disease has killed millions of tanoak trees and several oak tree species in forests throughout California since the mid-1990s.   

Pine shoot beetle and gypsy moth are not currently in California, but they could damage the state's Christmas tree plantations and forests if they were to become established.

Pine shoot beetles, Tomicus piniperda, feed on shoots, stunting the growth of pine trees. Large populations of the insects can kill apparently healthy trees.

Gypsy moth, Lymantria dispar, attacks forests and landscape trees, including manzanita, western hemlock, Douglas fir and live oak. Gypsy moth caterpillars feed on hundreds of plant species and are capable of defoliating trees at an alarming rate. A single gypsy moth caterpillar can eat up to one square foot of leaves per day, according to the California Department of Food and Agriculture. 

“According to the Don't Move Firewood website, Christmas trees are generally deemed safer than firewood in terms of invasive pests,” Alexander said. “However, safe disposal of trees is still important.”

For more information about sudden oak death and forest health, visit Alexander's website at http://cemarin.ucanr.edu/Programs/Custom_Program816. More information about holiday greenery pests can be found at the USDA APHIS website and the Don't Move Firewood website http://www.dontmovefirewood.org/HolidayGreenery.