Citrus pest moves to Tulare, leading to new quarantine

Growers are gearing up to comply with quarantine restrictions on the movement of citrus fruit in Tulare County, one of the nation's top citrus-producing regions. The action was triggered at the start of the California navel orange harvest after a second Asian citrus psyllid was found within a year in an insect trap in a commercial grove.

The pests have been found in groves near Strathmore and Terra Bella, in southeast Tulare County, near the Kern County border.

The psyllid is considered a serious pest because of its ability to transmit a fatal citrus disease known as citrus greening or huanglongbing, which has caused significant tree losses in Florida and other citrus-growing regions.

Tulare County growers who end up in the quarantine zone will continue to have access to packinghouses that also are in the restricted area. Experts say citrus nurseries in the quarantine zone, however, may face serious challenges. Unless the trees are grown in screened enclosures, they can't be shipped out of the quarantine zone, Tulare County Agricultural Commissioner Marilyn Kinoshita said.

There are about 20 citrus nurseries in Tulare County and, as protection against Asian citrus psyllid infestations, U.S. Department of Agriculture regulations now require screening for citrus propagation material beginning Jan. 1. A number of nurseries have installed protective growing structures in advance of the requirement, but how much more needs to be done to achieve compliance with the immediate quarantine was unknown at our deadline.

"Regulations requiring protective structures have been in place for a couple of years," said Tom Delfino, California Citrus Nursery Society executive director. "As far as what comes next—it's a risk decision that citrus nursery operators will need to evaluate and then decide how to proceed as the quarantine is imposed."

The psyllid trapped in Tulare County most recently was not in suitable condition to be tested for the bacterium that causes huanglongbing.

Infected trees die within a few years of being infected. There is no cure for the disease, which has killed commercial citrus groves in Florida, Brazil and other major citrus-growing regions around the world.

The aphid-sized psyllid was first identified in California in 2008 and had earlier been found in Imperial, San Diego, Los Angeles, Orange, Riverside, and San Bernardino counties, where quarantines are also in place. But, with the exception of one backyard citrus tree in Los Angeles County, the HLB disease has not yet been found in California.

Tulare County farmers produce navel oranges valued at about $500 million a year and harvest of this season's crop is under way. Overall, Tulare County citrus production, including nursery stock, exceeds $750 million a year from nearly 120,000 acres. According to government statistics, the county produces about half of all California-grown oranges and more than one-third of the state's tangerines.

Due to the new quarantine restrictions, Tulare County commercial citrus growers, citrus nurseries and those with backyard trees are prohibited from moving fruit outside the quarantine zone.

"From the growers' perspective, this will cause additional costs for those inside the quarantine area, especially if they deliver their fruit to a packinghouse outside the quarantine zone," said Ted Batkin, California Citrus Research Board president. "Otherwise, it will be business as usual for most growers."

Growers in the zone can continue to operate because packinghouses will process fruit for shipment, Kinoshita said, but the biggest effect could be on nurseries that grow trees for sale to farmers or garden centers.

"We know the quarantine area is growing," said Tricia Stever Blattler, Tulare County Farm Bureau executive director. "There are literally hundreds of growers who will be impacted by this situation."

The situation is still coming into focus for growers, said citrus farmer Ed Needham, a Tulare County Farm Bureau director.

"It's too early to know the full impact of the quarantine," Needham said. "I don't know right now if my citrus in Delano will be included, for example. This thing is moving fast and it's hard to say what the impacts will be tomorrow."

Researchers warn that experience with the pest-disease combination in other parts of the world suggests the disease bacterium follows psyllid infestations within a few years. California citrus farmers have assessed themselves to pay for research and testing to address the increasing pest-disease threat.

Community and grower meetings were scheduled to be held this week in Tulare County to explain the quarantine requirements and restrictions, with a special meeting to discuss requirements for commercial and retail nurseries scheduled Dec. 3 at the Tulare County agricultural commissioner's office.

(Kate Campbell is an assistant editor of Ag Alert. She may be contacted at kcampbell@cfbf.com.)

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