Date: Sep 02, 2014
Magazine:
September 2014 -- WG Annual Meeting to be Held in Vegas

Citrus grower Nick Hill of Green Leaf Farms, Kingsburg, CA, said the Golden State’s citrus industry has learned a lot about the Asian Citrus Psyllid and the devastating citrus greening disease that it can spread because of the mistakes made in Florida.

“They admit they made a lot of mistakes and we have learned a lot because of it,” he told WG&S in mid-August.

California is in the midst of a fight against the Asian Citrus Psyllid and the Huanglongbing (HLB) disease it can transmit.  Florida has lost millions upon millions of dollars and an untold number of trees to the disease.  So far, while the psyllid itself is fast becoming entrenched, at least in Southern California, only one diseased tree has been found in the state.

Victoria Hornbaker, citrus program manager for the California Department of Food and Agriculture (CDFA), said that one tree was found in a neighborhood backyard in the Southern California community of Hacienda Heights in 2012.  She said experts are surprised that there have been no further finds, but she credits quick work by CDFA and the industry to mitigate that problem and do everything possible to prevent its spread.

Hornbaker said she is a “glass half-full kind of person” and she’d like to think that the tree found in Hacienda Heights and the subsequent eradication efforts of CDFA have been successful.  However, she is also a realist and the entrenchment of the pest in Southern California and the continual finding of the tiny insect in many areas of the state, drives home the point that this is an ongoing situation and California cannot ever let its guard down.

In fact, she said long term hopes center on finding a cure for HLB rather than totally eradicating the Asian Citrus Psyllid.  “The psyllid is just a nuisance that we can deal with it.  The bacteria that it can transmit from tree to tree is devastating.”

The citrus greening aspect of HLB renders a tree useless and can devastate a grove in a relatively short time frame.  Of course, another challenge with the disease itself is that a tree can be infected but not show signs for several years.  In the meantime, pests can carry the bacteria from one tree to the next.  In fact, in the Florida postmortem, Hill said the Florida industry was busy concentrating on citrus canker while the HLB disease spread somewhat silently.

Hornbaker said it is believed that the movement of citrus stock from one area to another was a major cause of the spread of the problem in Florida.  In fact, the disease manifestation in Florida has been traced to budwood that was brought into Florida from Asia.  Similarly, the one find in California also appears to have come from budwood from Asia.

Consequently, the CDFA effort is concentrated on preventing the movement of nursery stock, budwood, branches or leaves from one area to the next.  More than 45,000 square miles of California real estate are currently operating under quarantine conditions.  Those rules specifically prohibit the movement of nursery stock out of the quarantine zone and require that citrus being trucked from one grove in a zone to a packing shed outside of the zone be tarped.  While the psyllid does not inhabit the fruit, it does live on the foliage and the wood of the trees.

For this reason, Hornbaker said it is also very important that harvesting and other farm equipment be cleaned in the grove before moving from one grove to the next.

Hill who has groves in quarantine zones and packing sheds outside of the zones said following the quarantine rules is extremely important.  He said the CDFA trapping and spraying program has apparently been very effective in preventing the disease to spread, but he said growers have to be vigilant in doing their own part.  He is the current chairman of the Citrus Pest and Disease Prevention Program and knows the rules inside and out.  Hill said most growers are well-versed on the subject “but there are always pockets of people that might not be clued in.”

Hornbaker urged growers to make sure their employees and PCAs (Pest Control Advisor) are “trained up” on what to look for when it comes to the psyllid and the HLB.  “The committee and the CDFA has invested a lot of time and effort in conducting outreach programs to both growers and in urban communities,” said Hill, but he indicated that there is always more work to be done.

While most growers are very clear as to what they can and can’t do, the same is not true for your average urban homeowner with a citrus tree in his backyard.

Hornbaker said CDFA has been very aggressive with its trapping and testing program and so hopefully early detection will occur if there is another diseased tree find.  She said early detection is key to stopping the spread of HLB. 

But Hill reiterated Hornbaker’s supposition that finding a way to deal with the disease itself is the long-term goal.  “Ultimately that’s the holy grail,” he said.  “We need to find resistant trees or find a way to make it impossible for the psyllid to transfer the disease.”

Hornbaker said there is much research going on in citrus production regions all over the world to find a “cure” if you will for HLB.

In California, Hornbaker said it is the resources of the citrus industry that have allowed for the robust trapping and detection that so far has proven to be successful.  The citrus industry has assessed itself eight cents per field carton to fund the project.  Hornbaker said the funds collected, combined with some federal grant money, has allowed CDFA to maintain a level of vigilance that is necessary to stay ahead of this issue.  She added that additional funds would be helpful and would allow a further expansion of the program.

Both Hill and Hornbaker had a similar response when asked how growers could help.  More training they both said.  The CDFA official repeated that early detection is the key and so the more people out there looking for psyllids and looking for the disease, the better off the industry will be.

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