http://www.cfbf.com/agalert/AgAlertStory.cfm?ID=1431&ck=E11943A6031A0E6114AE69C257617980
Pest quarantines disrupt farms and nurseries
Issue Date: November 25, 2009
By Steve Adler
Citrus nursery operator Steve Maddock of Fallbrook,
whose business falls within a newly expanded quarantine
for Asian citrus psyllid, stands next to one of the traps set
to monitor the possible spread of the tiny insect that
threatens citrus trees.
For many invasive pests, San Diego County serves as the port of entry to the rest of California. That point was driven home once again last week with the establishment of a quarantine for one unwanted insect and the extension of quarantine boundaries for another.
The unwelcome guests in these instances are the Mediterranean fruit fly and the Asian citrus psyllid. The quarantines address new infestations of each pest in northern San Diego County.
The Medfly, which threatens more than 260 host crops, has been discovered in California many times in the past 30 years and eradication efforts have been successful in each instance.
The psyllid, which is about the size of an aphid, can carry huanglongbing, or HLB, a bacterial disease that has devastated citrus-growing regions throughout the world. Florida has lost a third of its citrus acreage since HLB was found in commercial groves there in 2005. More than 200,000 acres of citrus have been removed to date in Florida, with more removals expected.
Although the psyllid has been found in California, the HLB virus so far has not been detected. Quarantines have been set up to stop the psyllid's spread and assist in its control and eradication, in places including Los Angeles County, most of San Diego County and parts of Imperial, Orange and Riverside counties. There have also been isolated psyllid finds in Sacramento and Fresno, in air-parcel delivery facilities.
The quarantines cause particular hardship to growers who operate within their boundaries. For example, Maddock Nursery in Fallbrook produces citrus nursery stock used in commercial groves. But one of the provisions of the psyllid quarantine is that no citrus stems or leaves can leave the quarantine area, so shipments of nursery stock from Maddock to customers outside the quarantine have come to a halt.
"We would like to know what it is going to do," nursery operator Steve Maddock said. "We are waiting for answers. It may be a matter of restricting shipments to within the quarantine, but we don't know the specifics."
"The citrus nurseries inside the quarantine zone have several years' worth of trees in stock to sell and suddenly, boom. It's a stop order and they cannot move those trees out of the quarantine area," said Eric Larson, executive director of the San Diego County Farm Bureau. "The market in an area like San Diego is far too small to absorb all the trees they produce."
Larson said he sees the effort to control the psyllid as a long-term, entrenched battle.
"A couple things have to be done. The fight has to continually take place here to eliminate the infestations that we find, but just as important is the elimination of the infestations on the border regions of Mexico so we don't suffer new infestations. These insects don't heed the international border," Larson said. "We love the relationship that we have with Mexico, but it certainly causes us grief when it comes to insects. So even if we are successful on this side of the border, we have to be very concerned about new infestations."
Citrus growers inside the psyllid quarantine are allowed to ship their fruit, but only after it meets certain protocols involving the cleaning of the fruit in the field before it is sent to a packinghouse outside the quarantine zone.
This adds a new step and additional expense to the harvesting process. Portable brushing and cleaning equipment needs to be brought into the field. Once the fruit is picked, it is moved into these portable machines and run through a line where it is brushed clean. It is then reloaded into clean bins and delivered to the packinghouse, Larson said.
Researchers suspect that the psyllid can survive year-round in California's citrus-producing areas, which has prompted quick action by county, state and federal pest fighters to knock down, control and perhaps eradicate the pest from the state.
Robert Leavitt, acting director of plant health and pest prevention services at the California Department of Food and Agriculture, notes that California is the only major citrus fruit production area in the world that is free of the HLB bacterium. Treatment and eradication efforts are ongoing in both California and Mexico, he said.
"It isn't just a threat to California's commercial citrus; it is a threat to everybody's citrus. Our survey in Los Angeles, for example, shows that every other house has at least one citrus tree in the yard. So it is a major threat to the culture of Los Angeles," Leavitt said.
Bob Wynn, CDFA statewide coordinator for the Pierce's Disease Program, has also been involved in Asian citrus psyllid eradication efforts. He said the psyllid program utilizes a regimen similar to that used to combat the glassy-winged sharpshooter, which carries Pierce's Disease in grapes.
"We use a two-fold treatment, starting with a foliar treatment with an insecticide that kills the adults and then we follow up with a systemic treatment, so that if there are any eggs on the plant that hatch out later, they are killed as well," he said.
According to Wynn, CDFA is working very closely with the U.S. Department of Agriculture, the states of Arizona, Texas and Florida, and with Mexico and Belize, which have both the psyllid and the HLB bacterium.
The experts don't expect the Asian citrus psyllid to be eradicated anytime soon in California, but there is the hope that its movement can be limited to areas without extensive commercial agriculture.
"No one is predicting when the psyllid quarantine will end because they keep having new finds. But I have heard that they are having good luck with eradicating it at the sites where it has been found," Larson said.
On the other hand, there is hope that San Diego's new quarantine for the Mediterranean fruit fly may end as soon as June or July, assuming that no new flies are found.
"The quarantine lasts for three life cycles from the time that they find the last live fly. So every time that you find a new fly, the clock starts over again," he said.
That quarantine was established after three flies were taken from traps in the Fallbrook area of San Diego County between Oct. 29 and Nov. 1, triggering a quarantine of approximately 79 square miles. CDFA crews are already conducting eradication procedures in the Fallbrook area. Aerial release of sterile flies is being done at a rate of 250,000 sterile flies per square mile per week, over nine square miles surrounding the finds. The sterile male flies mate with wild female flies, reducing the pest's population.
CDFA crews also are working with local growers, packinghouses, transporters, farmers markets and other related facilities to ensure compliance with the quarantine regulations. According to CDFA, a permanent Medfly infestation in California could result in estimated annual losses of $1.3 billion to $1.8 billion.
(Steve Adler is associate editor of Ag Alert. He may be contacted at
sadler@cfbf.com.)
