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Eucalyptus bugged by pests

Suzie Harrison

Lerp psyllids and eucalyptus trees shouldn’t be mistaken as friends,

despite the fact that they are seen in public together.

The psyllid, an insect and unwelcome pest of the eucalyptus, is, in

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fact, damaging and killing the trees throughout Laguna Beach.

The problem starts when the lerp forms a protective white shell of

crystallized honeydew on the leaves of the trees; the shell or “lerp”

protects the insect.

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These insects extract energy from the tree and block sunlight,

impairing tree growth and health.

Though there is not a specific infestation now, workers still are

looking into how best to treat the trees, said Victor Hillstead, the

city’s parks and buildings manager.

“We’ve been treating the infected trees in the downtown area with an

injection system, injected right into the base of the tree,” Hillstead

said. “The chemical works its way up and down the tree.”

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No chemicals have to be put on foliage as part of this treatment. The

injection is not a health hazard to humans.

“The only thing with this process is that it only lasts six to nine

months and that’s primarily because of constant, sticky drip the psyllids

create,” Hillstead said.

To a great extent, they are able to neutralize the growth of the lerp

and are able to sustain the health of the tree.

Psyllids were originally found in Brisbane, Australia in 1964, but

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they were not seen in Southern California until June 17, 1998.

The city has treated about 150 trees with the injection, Hillstead

said. The cost of the injection is based on the circumference of the

tree, averaging about $50 a tree or 93 cents an inch.

An alternative treatment is being developed by UC Berkeley professor

Donald Dahlstein, the leading researcher on the problem. As part of his

study, he is releasing tiny Australian wasps, about the size of a grain

of rice, that prey on the psyllids.

Through the university, Laguna’s parks department is doing a

controlled release of the predatory wasp, which has been kept under a

watchful eye up and down the state, Hillstead said. Thus far they haven’t

shown any signs of movement.

Hillstead says he expects to lose about 125 trees before the

infestation is defeated.

While there are about 250 varieties of the eucalyptus, only three are

primarily affected by the insect: Flooded Gum, Red Gum and Lemon-scented

Gum.

“The strain of lerp affects the citrus and those are the eucalyptus

trees on Broadway, with the real smooth bark,” said Hillstead.

The department is replacing the trees with Silver Dollar eucalyptus.

They are using those trees because they are resistant to the psyllids.

“Spring is the worst time of the year for the eucalyptus, when the

lerps are starting to be in full force,” Hillstead said.


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