California Olive Growers Battle Tiny but Destructive Pest

California’s olive growers are battling a tiny Mediterranean pest that farmers say could devastate their industry in just a few years if it continues to spread at its current rapid pace.

Found just two years ago on ornamental trees in backyards and highway medians throughout Southern California, the pinhead-sized olive fruit fly has since migrated into the San Joaquin Valley, the heart of the state’s $100-million commercial olive industry.

“It is a dire situation for us--this little beast only likes olives,” said Janet Nelson, manager of the California Olive Committee.

Although no serious damage to commercial crops has been reported, industry leaders said the pest has the potential to wipe out orchards if left alone to feed and multiply.

Entomologists said the olive fruit fly, Bactrocera oleae, is the world’s most dangerous olive pest. Its larvae tunnel into the fruit, where they grow to adulthood feeding on the infested olive flesh. An invaded orchard’s fruit will drop prematurely, reducing yields. Oil volume is reduced and acidity levels rise during an infestation.

Olive growers in California are bitter that their industry, which represents just a fraction of the state’s $30-billion-a-year agricultural sector, isn’t getting nearly the kind of federal and state assistance that grape growers have received in their efforts to combat the dreaded glassy-winged sharpshooter.

“The state said they can’t do anything because so many of the finds are in urban areas, and although they are spraying for the glassy-winged sharpshooter, they won’t spray for the olive fruit fly,” Nelson said.

The sharpshooter, which carries Pierce’s disease, has been blamed for $400 million in damage to Southern California vineyards and is the target of a $30-million eradication program begun earlier this year that has included monitoring and ground spraying of pesticide.

State agriculture officials believe the olive fruit fly has been steadily migrating north from Mexico for the last three or four years, hidden in smuggled shipments of olives or simply flying across the border.

Last year only one was found in Tulare County, which accounts for about 55% of the state’s olive production. Already this year, more than 300 olive fruit flies have been trapped there. And authorities believe that is just a fraction of the total population now at large in the San Joaquin Valley.

The bug has been found in ornamental trees in San Luis Obispo, Alameda and Yuba counties, as well as in other olive-producing counties such as Madera, Kern, Merced and Fresno.

“I was hoping that our state secretary of agriculture would step in and do something to eliminate the fly, but I’ve been a little disappointed in that,” said Pat Akin, who farms 55 acres near Ivanhoe in Tulare County. “We’re a small industry, and this is what happens to small industries, I guess.”