Agricultural officials appear to be on the verge of victory in the war against the Mediterranean fruit fly in the San Fernando Valley.
The last two weeks of August marked an important stage in the fight against the Medfly infestation: Time for a full generation of the flies came and went, with not one new wild Medfly discovered since July.
That means the plan that federal, state and county agricultural agencies agreed on is working--a one-time pesticide treatment followed by the release of millions of sterile male Medflies and imposition of a quarantine on home-grown produce in a 62-square-mile area of the Valley.
"If we were going to find something, we would have found it in the last two weeks," said Dorthea Zadig, program manager for the state Department of Food and Agriculture. "That obviously could change, but it's making us feel good. . . . We passed what we could call some kind of a goal."
6 Medflies Found
Since the infestation was discovered July 20 in Northridge, six wild Medflies have been found in the state's traps.
State, county and federal agriculture officials responded by treating a 16-square-mile area July 25 with the chemical malathion. In early August, the release of about 300 million sterile Medflies began an effort to breed any remaining wild Medflies out of existence.
The Medfly is a potent pest that lays its eggs in a wide variety of fruits and vegetables. When the eggs hatch, the larvae make the produce inedible. A disastrous Medfly infestation in 1981 cost the state $97.6 million to eradicate.
By the end of August, one complete generation of Medflies is thought to have come and gone since officials began releasing the sterile male flies, Zadig said. The sterile fly release will continue at a rate of 40 million a week for one more generation, through this month, she said.
Efforts to Escalate
Officials plan to intensify trapping efforts for another month, and hope to declare the pest eradicated if no more wild Medflies show up by the end of October, said William Edwards, chief deputy to the Los Angeles County agricultural commissioner.
The state quarantine is expected to remain in effect until eradication is declared, Zadig said. The quarantine bars anyone from removing home-grown produce from the designated area, which includes much of the northwestern Valley. The zone is roughly bounded by De Soto Avenue on the west, Woodman Avenue on the east, the Simi Valley Freeway on the north and Burbank and Victory boulevards on the south.
The quarantine affects about five small Valley produce growers and about 30 nurseries, said state agriculture biologist Dee Sudduth. Nearly all have cooperated fully with the quarantine, she said.
Nurseries are stripping fruit from trees before sale, and drenching the soil around potted plants with the chemical diazinon to kill off Medfly larvae or pupae that might have fallen from the leaves.
Produce growers have had to allow their crops to be treated with malathion four times, with treatments 10 days apart. They have had to keep ripe produce covered or screened, so stray Medflies cannot lay eggs in it, Sudduth said. One wholesale grower had to stop selling to restaurants outside the quarantine area until the countermeasures began to take effect at the end of August, Sudduth said.
Grower Beth Bollinger, who runs a Northridge produce stand with her husband, said the timing of the infestation and quarantine has cost the couple several thousand dollars. Bollinger's first harvest of tomatoes and peppers ripened when the quarantine began, meaning it could not be sold before undergoing the weeks of chemical sprayings. The harvest of about 1,000 plants would not stay ripe that long.
"They told me I could let it rot on the vine or tractor it up," Bollinger said.
Bollinger let most of the plants rot and uses screens and nets to cover the small number of survivors.
"I don't mind screening it, but it's a deterrent to customers," she said. With the screening, the fresh produce "is not as attractive, not as eye-catching."
Grower Dodie De Geyter of Van Nuys estimated a loss of several hundred dollars from having to destroy one of her three tomato harvests. She and Bollinger said eradicating the Medfly makes their sacrifices worthwhile.
"We gotta get rid of it," De Geyter said. "It'll ruin the whole state of California, the crops."
Authorities are "developing a case" against one quarantine-area fruit stand that has frequently left fruit uncovered, said Fred Meyer, who is in charge of the quarantine for the U.S. Department of Agriculture. Meyer declined to identify the fruit stand or say what action might be taken against it. Disobeying the quarantine is a misdemeanor violation of state law, and the penalty could vary from a fine to seizure of fruit or the forced closure of the stand, he said.