Los Gatos Weekly Times
Fruit fly invasion raises concerns
A “disastrous” pest that agricultural officials fear could lead to the destruction of entire crops has gotten loose in two Bay Area counties, and they're now preparing new rules on locally grown produce to contain its spread.
The detection of oriental fruit flies — bright yellow and not much bigger than a housefly — has prompted officials to declare a quarantine of homegrown and other locally bred fruits and vegetables in portions of Santa Clara and Contra Costa counties through mid-2024.
An invasive pest native to Asia, the fruit flies are known to burrow into hundreds of types of fruits and vegetables, rendering them inedible. Among the crops most susceptible are key California crops such as avocados, apples, citrus fruits, tomatoes and peppers.
“It would be disastrous for the oriental fruit fly to get established in Santa Clara County and California,” Joe Deviney, the county's agricultural commissioner, said in the statement. “We all need to be vigilant in protecting our agricultural and natural resources. Please do not bring or ship any fruits, vegetables or plants into California without ensuring they are permitted by law.”
In an effort to prevent the spread of the flies, the Santa Clara County quarantine covers a 112-square-mile area that includes the entirety of Santa Clara and portions of Cupertino, Milpitas, San Jose and Sunnyvale.
In Contra Costa County, the quarantine is a 99-square-mile area, prompted by the discovery last month of seven male oriental fruit flies. Included are most of Brentwood and portions of Oakley, Discovery Bay and Antioch.
Matt Slattengren, Contra Costa County's agricultural commissioner, said the infestation
by this kind of fruit fly is the first he's experienced in his 23 years with the county.
The flies can infest most fruits and vegetables, he said, and one female can produce 1,500 eggs in a lifetime, which allows the population to grow and spread rapidly. Adult flies live about 90 days.
“This is pretty close to (Contra Costa County's) agricultural core, where we do most of the growing,” Slattengren said. “Some people will lose their entire crops over this.”
Under the quarantine, which is expected to last until June 1, 2024, residents within the limits are required to keep homegrown fruit at their residence. The crops can still be eaten or processed, but if they're disposed of, the remains must be double-bagged and sealed.
Some businesses — including farms, plant nurseries, farmers markets and fruit vendors — will also be affected by the quarantine. County officials will work with businesses in establishing compliance agreements to prevent infested materials from being removed from quarantine areas.
The West Coast Farmers Market
Association, which operates 11 farmers markets across the Bay Area, has been told it will be impacted, said Jerry Lami, the group's executive director.
Lami said many fruits and vegetables will need to be covered with cloth or plastic wrap, which would prevent insects from landing on them and laying eggs. Vendors will be required to bring fewer crops to markets, as leftovers won't be allowed back on farm property after being exposed at market.
He said officials in the South Bay were still trying to determine which fruits and vegetables the flies might be targeting.
Contra Costa County announced its own infestation of oriental fruit flies at the end of August, after officials said they had detected seven male flies near Brentwood and Oakley. On Sept. 6, the state farm and agriculture department released its quarantine boundaries, based on the results of a survey to determine the pests' spread.
In neighboring Sonoma County, where a quarantine is not in effect, officials said they were working to obtain compliance agreements from those who move crops and those who receive them.
“Contra Costa County has a small but robust grape crop of between about 15,000 and 20,000 acres, and as they sell their grapes into counties without a quarantine, they'll have to get that compliance agreement,” said Andrew Smith, the agricultural commissioner in Sonoma County. “The agreement basically states that the supplier is going to take these steps so that they don't spread the pest while in transit.
“Both the shipper and the receiver sign the agreements. That way, they both know how to handle the fruit, how to move it in appropriate time and how to handle it if the product hasn't been handled well to that point.”
A quarantine of a similar scale was imposed in 2021 when oriental fruit flies were discovered in the Santa Clara Valley. The quarantine mostly focused on the southern part of San Jose.
During the quarantine, the California Department of Food and Agriculture will place bait on trees, poles and other surfaces near the area where the flies were found. The bait contains an organic pesticide, spinosad, which kills the flies. According to the county, this method is safe for people and pets.
The announcement comes less than two weeks after Santa Clara County said it would spray for oriental fruit flies after finding only two of the insects in the region.
Two South Bay women were recently charged with the illegal importation of fruit after they allegedly organized the transportation of the tropical tree fruit langsat from Vietnam in 2022. Portions of the fruit were found to contain the larvae of an invasive species of fruit fly native to South Asia.
Officials on Sept. 6 did not suggest any link between the Santa Clara County oriental fruit fly infestation and the illegal fruit-import charges.