HomeMy WebLinkAboutStatus of Red Gum Lerp Psyllid April 24, 2000
MEMORANDUM
TO: KEITH TILL, CITY MANAGER
FROM: DAN DORSEY, ASSISTANT TO THE CITY MANAGER
SUBJECT: STATUS OF RED GUM LERP PSYLLID (RLP)
INFESTATION ON EUCALYPTUS TREES WITHIN
CITY OF SEAL BEACH
BACKGROUND
The red gum lerp psyllid (RLP), a new pest on California's red gum eucalyptus trees, was
discovered in 1998 in Los Angeles County and has currently spread throughout much of
the state. Both the psyllids and the eucalyptus are native to Australia.
Lerp psyllids are small insects which feed on eucalyptus leaves. The resultant leaf
damage may stress the trees and make them susceptible to attack by other insects or
diseases. Affected trees begin to defoliate; eventually, some of the trees may die.
Psyllids also produce a sticky substance called "honeydew," which can stain large
sections of sidewalks as well as vehicles.
In addition, lerp psyllids build miniscule domes on the eucalyptus leaves. This home, or
"lerp," protects young psyllids and also renders the pest largely immune to chemical
sprays.
CONTROL OF THE RED GUM LERP PYSLLID
Scientists are attempting the combat the psyllid without spraying insecticides—which can
be hazardous as well as expensive. Researchers are focusing on a biological control. Dr.
Donald Dahlsten, an entomology professor at the University of California, is heading an
effort to release a species of parasitic, non-stinging wasp (Glycaspis brimblecombei)
from Australia, which will prey upon the psyllids. The proposed wasp release will be
managed by the UC system and funded by UC and the Statewide Integrated Pest
Management Program.
LERP PSYLLID INFESTATION WITHIN CITY OF SEAL BEACH
The City has an identified infestation of red gum lerp psyllid at the eucalyptus grove
along Seal Beach Boulevard, between Lampson Avenue and Rossmoor Center Drive,
north of the 1-405 Freeway. The City is requiring the preservation of 70% of the existing
trees over 12" in trunk diameter at a point 4.5' above the ground as a condition of the
Bixby Towne Center Project.
The City has received a "Tree Preservation and Management" plan prepared by Greg
Applegate, a Certified Arborist, regarding the general health of the grove. The plan
indicates that the trees are over 50 years old and that the foliage is heavily-infested with
red gum lerp psyllids.
The City has indicated its interest in participating in a viable eradication program to
ensure the long-term health and viability of this important grove of trees within our
community.
TIMETABLE AND LOCATION OF WASP RELEASES
Researchers from the University of California—including Dr. Dahlsten—are scheduled to
meet with officials from Orange and Los Angeles Counties this week in order to identify
possible "wasp release sites." Because funding for this program is rather modest,
entomologist Nick Nissen of the Orange County Agriculture Commission speculates that
only two to three release sites will be selected in Orange County.
However, Greg Applegate, the arborist working on the Bixby grove, indicates that the
wasps would disperse at a rate of between 30-60 miles a month. Accordingly, regardless
of the release sites, Mr. Applegate believes that the parasitic wasps would probably arrive
in the Bixby grove within two to three months.
No precise timetable for the release of the parasitic wasps has been established as of yet.
However, most of the participants in the lerp psyllid eradication program have indicated
to staff that release of the wasps will probably occur around the end of April /early May.
Respectfully submitted,
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