Some movers and shakers in California’s $1.3 billion citrus industry concur it is a matter of when, not if, the deadly Huanglongbing (HLB) disease is found in the Golden State.

Commercial citrus leaders, growers, packers, nurserymen, and others are implementing proactive measures to manage the almost inevitable outbreak of HLB in California.

The California-Arizona citrus belt is the only major citrus-growing region in the world where HLB has not reared its ugly head.

HLB, also called citrus greening and yellow shoot disease, is caused by the Liberibacter bacteria.

The primary vector is the Asian citrus psyllid (ACP), a small insect about the size of an aphid.

The psyllid thrives on citrus tree flush (new growth). In California and Arizona, flushes occur in the spring and fall. The ACP has been found in several Southern California counties and in Yuma County in southwestern Arizona. HLB has not been found in either state.

The disease kills every tree it infects. It initially causes misshapen fruit with a turpentine-like taste which renders the fruit unmarketable.

Classic HLB symptoms signs include blotchy mottling (uneven color distribution) in the leaf. The symptom resembles a zinc or manganese nutrient deficiency yet the blotchy mottling is more uniform with HLB.

HLB is a problem of global proportion, remaining dormant for more than a century in major citrus-growing areas in India, Pakistan, China, and parts of Southeast Asia. Then the disease spread to Brazil. The first case of HLB in the United States was detected in Florida in 2005. Within one year HLB stretched across the Sunshine State’s citrus belt.

HLB and other plant diseases are moving quickly around the planet today. Why?

“Globalization is the driving factor,” said Ted Batkin, president, Citrus Research Board (CRB), Visalia, Calif. “People and goods are moving more.”

Add to that the villainous nature of HLB, says Jim Cranney, president, California Citrus Quality Council in Auburn, Calif.

“One of the sinister things about HLB and why it’s so difficult is it has very latent symptoms,” Cranney explained. “A tree can be infected but there is no (immediate) visual sign of infection in the tree. It can take one-and-a-half years after infection occurs before yellowing leaves and other symptoms appear.”

Cranney, Batkin, and other California citrus leaders discussed the ACP and HLB in depth during the 62nd annual National Citrus Institute in San Bernardino, Calif. in November.

Batkin and other Western citrus industry leaders have traveled to Brazil and Florida to learn about the pest and disease. They have gleaned a plethora of information to develop plans in the West to minimize and control the ACP, and HLB if and when it is found.

The California and Arizona state Departments of Agriculture are heavily involved in the process, along with the USDA’s Animal and Plant Health Inspection Service (APHIS) and other groups.

Florida mistakes

Central Valley citrus grower Nick Hill participated in an international HLB conference in Florida followed by farm tours and walked away shell shocked.

More than 200,000 acres of productive Florida citrus acreage have been lost to HLB and the amount keeps growing, Hill reported. Up to $500 per acre, beyond regular production costs, is spent annually by growers for HLB scouting, detection, treatment, and tree removal.

“Florida in the last few years has spent more than $30 million for research to find a silver bullet to stop the disease,” Hill said. No such bullet exists today yet developing a resistant rootstock to the disease is the goal of researchers worldwide.

Florida citrus leaders are the first to admit that mistakes were made when the disease was first detected. At the time, growers were heavily involved in battling citrus canker disease and HLB took a back seat.

A communication breakdown occurred in educating homeowners with backyard citrus and commercial growers. Florida also failed early on to gain adequate state and federal funds to fight the insect and disease.

Very little tree re-planting has occurred in Florida since the ACP thrives on tree flush. The bottom line is HLB has devastated Florida’s citrus industry.

“It’s sad; they are like the walking dead and they know it,” Hill said. “They are trying to find a way to survive long enough so they can get back in the picture later on.”

Worldwide, the National Academy of Sciences estimates that more than 100 million citrus trees are infected with HLB in 40 countries, according to Hill. Brazil has removed more than four million trees. Brazilian growers there spend up to $1,000 per hectare on detection and eradication.