Posts Tagged: polyphagous shot hole borer

UC Cooperative Extension uses UC Irvine campus as a living lab

The trees at UC Irvine are continuing to decline, making the leafy campus a living laboratory for research on polyphagous shot hole borer, an invasive beetle that is ravaging the Southern California urban forest, reported Amina Khan in the Los Angeles Times. The borer kills by entering tree trunks and leaving behind fungus that will grow and serve as food for their young. The fungus spreads and kills the trees.

"The beauty of UCI is that it's a university, and they're used to researchers," said John Kabashima, an environmental horticulture advisor and entomologist with the UC Cooperative Extension in Orange County.

Another scientist on the project is Akif Eskalen, UC Cooperative Extension plant pathology specialist based at UC Riverside. Eskalen first identified the sesame seed-sized beetle in a South Gate avocado tree in 2012. 

Eskalen selected 130 sycamores at UCI for his experiment and divided them into 13 groups of 10. Four of the groups were treated with different insecticides; three were treated with different fungicides; and four others got one of each. Another group was given a beneficial bacteria found in some California trees that's thought to kill the fungus. A final group is serving as a control and received no treatment at all.

The scientists are allowed to cut down and section the trees, sample them, and even leave some infested trees alone. Having this flexibility is essential to understanding the success — or failure — of a given pesticide, Kabashima said: "That's why we're learning so much here at UCI."

UC Irvine gets landscape tree help from UC ANR

Hundreds of landscape trees on the UC Irvine campus have been infested with polyphagous shot hole borer, a pest introduced into California from Asia. UCI has assembled a team that includes UC Agriculture and Natural Resources experts to develop a management plan for identifying, removing, treating and replacing the ravaged trees, according to a UCI press release.

Polyphagous shot hole borer has been present on the campus for two to three years. The extent of the infestation  became apparent in the last few months when a significant number of trees began showing severe symptoms. UCI groundskeepers began to more closely examine a number of trees that appeared to be particularly distressed and worked with UC ANR staff to identify PSHB in early 2015.

A team of UCI staff qualified in tree management is receiving training from UC ANR (UC Riverside and UCCE) to properly identify and assess PSHB infestation. The team will monitor all trees on the UCI campus and, with input from faculty and students from UCI's Center for Environmental Biology, make the determination about which infected trees will be removed.

The news release suggests area property owners who suspect their own trees are infested with PSHB contact John Kabashima, UC ANR environmental horticulture advisor at the UC South Coast Research and Extension Center, 7601 Irvine Blvd., Irvine, CA 92618, pshb.ucce.oc@gmail.com.

Sesame seed-size insect is victimizing trees in Southern California

The polyphagous shot hole borer is taking up residence in California trees from San Diego to Santa Monica and as far east as Riverside County, drilling circular tunnels and spreading fungal spores that kill trees from the inside out, reported Amina Kahn in the Los Angeles Times Science Blog.

Akif Eskalen, UC Cooperative Extension plant pathology specialist at UC Riverside, wants to contain this invasive bug before it spreads throughout Southern California.

"If we can't control them," Eskalen said, "they are going to wipe out all our trees."

Box elders, sycamores, American sweetgum, maple and coast live oaks are susceptible to polyphagous shot hole borer attack. In urban and suburban areas, the dead and dying trees can pose fire and limb falling dangers. In the agricultural sector, avocado trees could face huge financial losses. In the fight against the pest, the California Avocado Commission has provided Eskalen $800,000 to broaden his investigation into this mysterious species of ambrosia beetle. 

In March, Eskalen and his colleagues - UC Riverside entomologist Richard Stouthamer and Huntington Library curator of woody collections Tim Thibault - spent two weeks in Vietnam, where PSHB originates, searching forests and fields for natural enemies of the fungus spread by the pest. They collected a host of possible allies, whose DNA is now being analyzed in the lab.

"I am very hopeful that we are going to find some solutions to control this fungus," Eskalen said. "We have to."

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