Commentary: California must hold the line on HLB citrus disease


Issue Date: April 12, 2017
By Nick Hill
Nick Hill
Asian citrus psyllids, can carry the fatal plant disease known as HLB. Psyllids have been found in many parts of California, but the disease has so far been found only in residential trees in Los Angeles County.
Photo/California Citrus Pest & Disease Prevention Committee
Asian citrus psyllids, can carry the fatal plant disease known as HLB. California farmers and pest-control officials hope to keep HLB at bay while researchers work on a cure for the disease.
Photo/California Citrus Pest & Disease Prevention Committee

As Florida faces its worst orange harvest in more than 50 years and Texas faces thousands of huanglongbing detections in its Rio Grande Valley, California citrus growers are grateful for another prosperous season untouched by the plant disease.

We've had HLB in California since 2012, but we've managed to keep it out of commercial groves entirely. During these five years, there have been fewer than 50 diseased trees identified, removed and destroyed—all in urban Los Angeles County.

In Florida, the disease was first discovered in 2005 and within two years was identified in all citrus-producing regions of the state. By 2012, the disease had cost Florida $4.5 billion and 8,000 jobs.

Our partners in Florida have told us time and again how critical it is to respond aggressively to pest and disease detections. Coordination is key, they said. Thus, a strong and coordinated response is the cornerstone of the Citrus Pest & Disease Prevention Program here in California.

Since its inception in 2009, the program has played a pivotal role in stopping the spread of HLB. Much of the program's work has taken place in urban areas where Asian citrus psyllid populations and disease likelihood are much higher than in commercial groves. For that reason, citrus growers may be unaware of the breadth of program activities.

In the core areas of Los Angeles County where HLB has been detected, the Citrus Pest & Disease Prevention Program partners with local and state agriculture authorities to visit thousands of properties several times each year, inspecting all citrus varieties, taking leaf samples and testing for the disease. When a tree is confirmed HLB-positive, it is taken out of the ground quickly—often in a matter of hours. Throughout the rest of California, agriculture officials use a risk-modeling system to identify areas that need focused inspections and sampling.

In 2016, the California Department of Food and Agriculture collected nearly 50,000 plant samples and nearly 80,000 Asian citrus psyllid samples to test for HLB. Since sample collection began in 2008, more than 400,000 plant and psyllid samples have been collected and processed.

For too long, Asian citrus psyllids were allowed unfettered access to citrus groves in Florida, as growers there focused on managing citrus canker. Florida growers have since developed a strong pest-management program, which served as inspiration for California's own take on Asian citrus psyllid control in commercial groves.

The Citrus Pest & Disease Prevention Program employs personnel throughout citrus production areas to help growers time their Asian citrus psyllid treatments in a coordinated fashion. Regularly spraying for the psyllid and coordinating with your neighboring growers will protect all our trees from HLB.

CDFA will treat residential properties located within 400 meters around commercial properties that are participating in an area-wide management program, if 90 percent of commercial citrus in the treatment area participates. This makes it even more imperative for growers to work together when treating for the psyllid.

As farmers, we already struggle with tight margins, limited resources and regulatory burdens, so it is natural for some to get weary of repeated Asian citrus psyllid sprays and other pest mitigation measures. But psyllid management is absolutely critical if we hope to remain ahead of this disease. California citrus growers must continue investing in prevention now, to secure more disease-free seasons in the future.

HLB has killed millions of citrus plants in the southeastern United States, but it has claimed just a few dozen in California. We must keep holding the line until a cure is found.

(Tulare County citrus grower Nick Hill chairs the California Citrus Pest & Disease Prevention Committee.)

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.