The western cherry fruit fly has not been found in California's cherry-growing districts.

The western cherry fruit fly has not been found in California’s cherry-growing districts.

State officials in Oregon and Washington say ­California’s quarantine requirements for the Western cherry fruit fly are unjustified.

Helmuth Rogg, supervisor of the Oregon State Department of Agriculture’s Insect Pest Prevention and Management Program, said California has imposed quarantine regulations for the western cherry fruit fly on incoming cherries for the past 50 years or so, even though the insect is native to California.

“This is fairly unique to my knowledge that one state

[California] quarantines other states for the same species that is in their own state,” he said. California requires special measures to prevent cherry fruit fly larvae from being shipped in Northwest cherries to California.

Jim Quigley, manager of the Washington State Department of Agriculture’s commodity inspection program, said that Washington conducts its own quarantine inspections for cherry fruit fly by doing a lot sample when the fruit arrives at the warehouse. However, cherries destined for California or travelling through California must be sampled again after they are packed. Two cherries must be sampled out of every box shipped there. The cherries are crushed and placed either in a sugar solution or hot water, which prompts any larva to wriggle out.


If cherries are exported through San Francisco or Los Angeles, for example, they must be trucked on a route that avoids the cherry growing areas, even though they are in sealed cartons in the truck and cannot be opened until their destination.

Quigley said California’s requirements in terms of inspections and special permits to ship to or through ­California are a burden on Northwest states.

Rogg said such requirements make no sense because the cherry fruit fly is established in the California counties of Del Norte, El Dorado, Lassen, Mendocino, Nevada, Plumas, Shasta, Sierra, Siskiyou, Trinity, and Tuolumne, and has been recorded in Humboldt, Placer, and Sonoma counties. It tends to be found at high altitudes.

According to the National Plant Board, a nonprofit organization that makes recommendations on state regulations concerning plant pests, if an insect is present in a state, that state can’t quarantine other states. To do so amounts to protectionism, Rogg said.

High altitudes

California has argued that the western cherry fruit fly has only been found at high altitudes and not in the commercial cherry-producing areas, but Rogg believes there is still no scientific justification for California’s quarantine measures, unless California argues that the western cherry fruit fly in California is a different biotype from the cherry fruit fly in Oregon, Washington, and Idaho. If that were the case, then Oregon, Washington, and Idaho could turn around and quarantine California’s cherries to keep the California biotype out of those states, he said.

California ships a large quantity of cherries to the Pacific Northwest. Rogg said some of those cherries are shipped in bulk, repackaged, and shipped back to California. On arrival back, they have to go through quarantine because the California Department of Food and Agriculture says they might be mixed with other states’ cherries.

It has reached the point where the Northwest states want to address the issue, he said.

Nick Condos, chief of the pest exclusion branch of the California Department of Food and Agriculture, said cherry fruit fly is known to exist only in high elevations of the state, where its host is Prunus emarginata (the bitter cherry). It has not been found in the commercial cherry-growing areas. The state has an interior quarantine designed to prevent its spread into production areas. Any commercial cherries grown in the areas where the fly is established would be subject to the same quarantine restrictions as cherries coming into California from other states, he said. However, there is no commercial cherry production in the areas where it has been found.

“If someone decided to start growing cherries in one of those areas, we would quarantine them just like cherries from Oregon, Washington, and Idaho,” he said.

If it could be proven, through research, that it is biologically impossible for the fly to complete its life cycle in the California production areas, then California would consider dropping the quarantine, he said, because it’s a problem to have to deal with enforcing the quarantine and issuing permits for incoming cherries.

However, to determine definitively whether or not the pest could exist in the environmental conditions of the San Joaquin Valley, for example, many thousands of pupae would have to be reared in similar environmental conditions. In addition, California’s trading partners would need to be convinced it was safe for the state to drop the quarantine, Condos said.