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California citrus industry mobilizes for HLB-vector psyllid

“The California citrus industry will not allow the Asian citrus psyllid to consume us,” says Ted Batkin, president of the California Citrus Research Board.

At a recent seminar for citrus growers at Exeter, Batkin traced the campaign that industry and federal, state, and county agencies have mounted against the aphid-sized insect that vectors citrus greening, the world's most lethal disease of citrus. There is no cure for it, and infected trees eventually die.

Also known as huanglongbing, or HLB, the bacterial pathogen is thought to be a native of China, where it earned its name for characteristic yellowing of new shoots in citrus trees. Fruit of infected trees remain green, are misshapen and bitter tasting, and cannot be marketed.

Established in Florida, Texas, Hawaii, and Mexico, where it claims a devastating toll on citrus, HLB, at this writing, has been not detected in California. However, the psyllid was recently discovered in San Diego County and tests are being made to learn if these finds are carrying HLB.

Plans for eradication of the pest as needed are in place.

Meanwhile, officials in the industry, the California Department of Food and Agriculture, and USDA agree it is only a matter of time before HLB reaches California citrus.

Batkin said a California HLB Task Force intends to deal with it immediately, rather than delay reaction as Florida and Texas did when it occurred there.

“Our plan is to take aggressive action, and we will treat the problem just like the medical community treats cancer: with early detection and rapid response.”

First, rather than conventional methods with sticky traps, detection in the effort is by a “sentinel tree” approach relying on a new flush of growth, the first attraction for a migrating psyllid. Flushes are initiated by pruning.

Citrus and other host plants, such as sweet orange jasmine, are being used in groves, backyards, and strategically placed pots. Once finds are made, maps will be made to track movement of the psyllid.

Second, resources for testing for HLB will be increased. Batkin said state, university, and USDA facilities are now available for the testing only five months of the year. Two labs with rapid-screening equipment will be added, one near the University of California, Riverside, and another in the San Joaquin Valley.

Third, citrus and retail nurseries will sample nursery stock for the insect.

The last part is consulting services for Asian citrus psyllid population control to help train as many people as possible as scouts in urban settings or commercial citrus groves. “We want to expand our eyes and ears throughout the urban population where the psyllid is most likely to come in. We expect it to turn up in a city rather than a commercial grove,” Batkin said.

The HLB emergency has prompted the Citrus Research Board to add an operations department headed by a vice president with staffing and equipment to carry out the sentinel tree monitoring, labs, and other functions. Initial costs have been met by the board's reserve funds. Previous research has been done by the board on a contract basis.

Batkin noted that the board is the only equitable grower-funded organization in the citrus industry, which spans from San Diego to Butte County.

A public hearing was scheduled for September to take testimony on a proposed increase in the industry's assessment rate to meet costs of the new program. The estimated budget for the 2008-2009 year is slightly more than $1.1 million.

“There is no tomorrow in dealing with this. We've been preparing for the last two years for the psyllid to come in. It is on our doorstep, and tomorrow is here today,” Batkin said.

Another dimension of the effort is a public education program, he added. “Based on previous experience with the light brown apple moth, fruit flies, and other invasive pests that have come in, we must engage the public in this process.”

In particular, any management or suppression measures against the Asian citrus psyllid will require public support after explaining to both the public and growers the importance of the program. Care is being taken to present a coordinated stream of accurate and consistent information from all participating agencies.

The deadly nature of HLB is the key message. “If you get a Med fly on an orange tree in the center of Los Angles, all you lose is your fruit. If you get an HLB-carrying psyllid in your tree, you will lose your tree.

“That will resonate with people, so we want to approach them properly with information and knowledge; we can enlist everyone to help us. We've never been turned down by a homeowner when we've asked to look at their tree after we've explained the risk.”

The Asian citrus psyllid, Batkin noted, is not confined to Southern California. It has been intercepted in San Francisco on shipments of curry leaves on airline flights from Hawaii. Trapping in the Bay Area and Central Coast, however, has not turned up the psyllid.

Action to be taken when psyllid finds occur, he explained, depends on the location and extent of infestation. Most homeowners prefer to spray their trees themselves, particularly when offered cost-sharing of material, but a larger infestation would require professional attention. The psyllid does not respond to baits, and imidacloprid is a successful material.

HLB is distinct in lethality from other citrus diseases, Batkin added. According to a retired USDA plant pathologist, while citrus canker and tristeza are like hemorrhoids, HLB is like lymphomic cancer.

Also on hand for the seminar was Joel Nelsen, president of California Citrus Mutual, who said talks were in progress with CDFA and USDA on budwood testing and inspection of nursery stock imported into California.

“We are also working with USDA to create additional research projects specific to needs of California, Arizona, and to a lesser degree, Texas. One of those is how best to eradicate a major population of the psyllid.”

He explained that Texas has a psyllid species that is not HLB-positive and if experiments with it are successful, California will have a basis for a more rapid eradication program in the event a major population shows up in the San Diego area.

Among other “firewalls” for California are improved trapping and additional inspection resources to protect from contraband product entering the country.

He said CDFA has been very supportive on HLB matters in the San Diego area and USDA is collaborating with Mexican authorities on inspection and eradication as necessary.

Texas and Florida, Nelsen said, have agreed to share what they know about HLB and the psyllid. “Everyone is on the same page that the citrus industry is developing. It's not government telling us what to do. It is the private sector helping government.”

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