Citrus disease's northward march worries valley growers

Oct. 17—The Central Valley's citrus industry is on edge after the incurable tree disease Huanglongbing was recently found in Santa Paula — a big step north that suggests it might not be long before the bacteria spreads to tiny, winged hosts already living in Kern.

Almost two dozen citrus trees have tested positive for the fatal sickness within a five-mile radius of the first two trees determined to have been infected in Ventura County. More than half those trees within a quarantine established Oct. 3 have been reported removed.

The disease, also known as HLB or greening disease, had never been found that far north. It was previously limited to Los Angeles, Orange, Riverside, San Bernardino and San Diego counties, where more than 6,300 trees have tested positive and been removed since HLB was discovered in California in March 2012.

Industry and government officials said Tuesday the concern is that HLB, carried by a tiny insect known as the Asian citrus psyllid, could potentially spread to the vast commercial groves of the Central Valley. Authorities reiterated standing precautions such as keeping backyard citrus on the same property where it was grown.

"This just brings the disease to our doorstep and makes it even more important for growers and the public to be vigilant about not moving citrus plants, parts and unclean/untreated fruit from quarantined areas," Kern Ag Commissioner Glenn Fankhauser said by email.

HLB is a bacterial infection harmless to humans and animals. Citrus trees catch it when an infected psyllid feeds on their leaves, leading to bitter, misshapen fruit and, ultimately, death. The disease has devastated citrus industries in Florida and Brazil.

In California, researchers are racing to find a cure or otherwise address what many consider HLB's inevitable spread to the Central Valley. Already the Asian citrus psyllid has been found in Kern and counties to the north.

"We're obviously very concerned about this new find," President and CEO Casey Creamer at the California Citrus Mutual trade group said. He noted that earlier predictions suggested HLB would have arrived in the Central Valley already, and so the plan now is to keep the pressure on.

"The industry's doing its part and we need some help and cooperation from the residents," Creamer said.

The most important precaution, he said, is for people to avoid transporting backyard citrus, especially fruit with a stem or leaves. Additionally, people are advised to make sure their trees are healthy and pest-free — or remove them if the trees are unwanted.

"I think everybody has to take it seriously. It's very easy for this to spread from one area to another if we're not following the regulations in place to protect the entire industry," he said. "It only takes one."

The quarantine set up by the California Department of Food and Agriculture this month in Santa Paula prohibits moving any citrus nursery stock, host plants or parts thereof outside the immediate area.

Commercially cleaned and packed citrus may be transported, but all other fruit must stay where it was grown, though it can be processed or consumed on the property. CDFA said the rules apply to fruit including oranges, lemons, grapefruit and kumquats.

Victoria Hornbaker, director of the CDFA's Citrus Pest and Disease Prevention Division, said she was less concerned about Santa Paula's proximity to the Central Valley than she was about the potential for the disease to be spread by harvest crews and other workers and machinery that travel between the two regions.

She noted progress is being made toward developing and introducing citrus varieties that resist or tolerate HLB, but that the process takes time. Not only do scientists have to find just the right tree, she said, but its fruit has to be commercially acceptable.

Another promising field of research she mentioned aims to integrate plant material from certain HLB-resistant plants into existing citrus varieties. But that takes time, too, Hornbaker noted.

"I'm always optimistic that the work we're doing today will give science the time to catch up and create a cure," she said.