Death by Lethal Injection

The new city of Laguna Woods may have to consider changing its name to Laguna Stumps.

More than 1,000 white flowering oleander trees and another 2,000 oleander shrubs, which for more than 30 years have been a fixture in the gated Leisure World community, have been infected with a disease and will have to be cut down.

But Laguna Woods is not alone. Throughout much of Southern California and as far east as Texas, a half-inch-long bug called the glassy-winged sharpshooter leafhopper is responsible for injecting a terminal illness into the ubiquitous oleander.

There is no cure for “oleander scorch,” which was first spotted in the region in the early 1990s in the Palm Springs area.

The problems at Laguna Woods--which expects to pay at least $1 million to replace the diseased trees and shrubs--pales in comparison to what it could cost the state, developers and homeowners who must deal with the dying plants, so common they are found in roughly 20% of home gardens in the state.

Caltrans estimates it would cost $52 million to replace the oleanders that line 2,000 miles of freeway in Southern California.

Because it needs little water or care once it is established, the oleander has become a mainstay at shopping centers, parks, schools and golf courses.

“It met all the criteria for a big, tough plant,” said Jim Engelke of EPT Landscape Architecture, Planning, Urban Design in San Juan Capistrano.

If oleander is the Superman of plants, it has met its Kryptonite.

After its discovery in Palm Springs, the scorch spread to Orange, San Diego, Riverside, San Bernardino and Los Angeles counties and has been found in Texas and Arizona.

Alex Purcell, a UC Berkeley etymologist, said he expects the scorch eventually will make its way to Northern California.

So far, the only other plant the disease may affect is periwinkle, a popular ground cover, but it has not troubled periwinkle in the wild, only in greenhouses.

Marcy Grebus, a plant pathologist at UC Riverside’s cooperative extension, finds sharpshooters “repulsive.”

“They have big beady eyes. It looks like a lizard head on a firefly,” said Grebus, who is using $25,000 from the California Assn. of Nurserymen to study the scourge.

The bug and the bacteria existed on separate sides of the continent when the sharpshooter, which is native to the Southeast U.S., hitched a ride to California. Then, for the first time, the bacteria had a means to infect the plant.

It spreads like malaria. The sharpshooter uses its needlelike beak to suck out the diseased fluid, injecting it when it feeds on a healthy plant. The disease plugs up the tubes that carry water from the roots to the rest of the oleander, turning the plant brown and eventually killing it.

The disease demonstrated its potential virulence in the 1880s, when a cousin of oleander scorch, called Pierce’s or Anaheim disease, wiped out the wine industry in Southern California and caused its move to Northern California.

Another strain has attacked citrus in South America. Researchers worry about the havoc it could cause in the rich farmland of the San Joaquin Valley if the disease attacked trees there.

As bad as dead plants look, the big concern outside of agricultural areas is that as the oleanders dry out, they become a fire hazard. The Orange County Fire Authority sent a letter to Leisure World officials telling them the oleanders had to be removed before fire season started.

Attempts to cut down the plants has met with widespread anger from the 18,000 residents of the newly incorporated Laguna Woods.

“But the residents have to understand, they will come down,” said John Lathrop, on the board of one of the homeowners associations.

The residents most affected live on busy El Toro Road, where the oleanders rise above a six-foot fence.

“I used to look out my kitchen window and see the trees,” Harriet McCullough said. “Now all I see is traffic and people staring into my windows.”

All this, of course, would be moot if there were a cure for oleander scorch.

“The strategy is to keep plants from becoming infected,” said Mathew Blua, a UC Riverside research associate. “How do we do that? Right now we don’t have a clue.”

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Infecting Oleanders

The glassy-winged sharpshooter leafhopper carries a strain of bacteria that causes leaf scorch in oleanders, an ornamental plant found throughout Southern California. The bacteria plugs the xylem (the plant’s water conducting system), causing the leaves to dry out. How it infects the plant.

1. The sharpshooter’s needle-like mouth parts (stylets) contain two tubes. One carries food into the body, the other carries saliva into the plant.

2. Muscles in the head move a diaphragm that pumps fluids to the stomach.

3. The precibarium has a valve that controls the direction of fluids. Experts suspect that the bacteria (xylella fastidiosa) is located here. It is not yet known how bacteria moves from insect into the plant.

Actual size: 1/2 inch.

Source: Department of Environmental Science, UC Berkeley / Alexander Purcell

Graphics reporting and graphic by RAOUL RANOA / Los Angeles Times