Campus to cut infested trees
A deadly infestation of tiny tree-boring beetles from Southeast Asia has reached the UC Irvine campus, and school officials say that several hundred trees will be removed.
Infested trees have also been identified on surrounding properties, including residential neighborhoods and public areas in University Hills. Scientists are grappling with the pest’s spread throughout Southern California
“It’s a significant threat to all of our trees,” said Richard Demerjian, UC Irvine’s director of environmental planning and sustainability.
Campus groundskeepers first noticed signs of a serious problem in December, and officials were able to confirm widespread infestation early this year. Tiny, telltale bore holes in trees are often undetectable unless the bark is removed. It’s estimated that the pests may have been introduced at UC Irvine two to three years earlier.
The polyphagous shot hole borer, a beetle about the size of a sesame seed, was first identified in Southern California in 2003, with major infestations in 2011 in Long Beach and Los Angeles. It has now spread to Riverside and Orange counties and San Diego.
The beetle infects a wide variety of tree species by boring to the core to begin its reproductive cycle. A fungus secreted by the beetle chokes the pulp and kills or seriously damages the host tree. Scientists have traced the beetle’s origin to Southeast Asia.
UC Irvine has assembled a faculty team to work on a management strategy with experts from the UC Division of Agriculture and Natural Resources as well as UC Riverside plant pathologist Akif Eskalen, who first identified the beetle fungus as the source of disease in the trees. There is no known treatment for infected trees.
According to UC Irvine, of the more than 25,000 trees on campus, about 1,000 have been identified as infested. Most will need to be removed. At least 16 species have been infected, with varieties of sycamores a favorite host of the beetle.
In an April 15 email to students and faculty, Vice Chancellor Wendell Brase explained the problem and the developing plan.
“We regret that many large trees will have to be removed ... but this is a necessary step in protecting the remaining healthy trees in our urban forest,” he said in the message. “Experimental treatment and prevention programs will place a priority on saving large mature trees, such as the 40- to 50year-old native sycamore trees in the central campus.”
The university will develop a program for planting replacement trees as information becomes available on species that are resistant to the beetle, school officials said. Proper disposal of the infected wood is also under examination.
Demerjian said scientists and students lament that the only course of action right now is tree removal.
“It’s hard to watch so many trees get cut down,” he said, “but people understand the necessity of this in order to manage the problem.”
UC IRVINE has discovered that hundreds of its trees, especially in Aldrich Park, above, are infested with a beetle from Southeast Asia and will be cut down.