Pest may sour state’s citrus
State agriculture inspectors are stepping up their efforts to battle what they believe is an agricultural time bomb.
After discovering what’s known as the Asian citrus psyllid in the Hillcrest neighborhood of San Diego last week, the farthest north the bug has been found in the city, agriculture officials warned that the bug was rapidly moving north since crossing the Mexican border at Tijuana in July.
The pest is responsible for spreading citrus greening disease and causing catastrophic damage to orange farms in Florida and Brazil. Agricultural officials warn that the same disease could be a catastrophe for California’s $1.2-billion citrus industry.
To slow the pest’s advance, officials have established quarantines in parts of San Diego and Imperial counties, prohibiting the movement of citrus plant material out of those areas. Fruit can still be shipped, but it has to be cleaned first.
For now, officials believe the state’s orange groves are still free of the disease. The danger is that the psyllid, a durable insect that can withstand freezing temperatures and hurricane-force winds, will find trees infected with greening and spread it across the state.
“We have never been threatened with a disease like this before,” said John Gless, a third-generation farmer from Riverside who wonders whether there will be anything left of his 6,000 acres of California citrus groves to pass on to his children and grandchildren who farm with him.
Southern California residents are unknowingly the first line of defense, because only their vigilance can provide the early warning agriculture officials need to save the industry, said Ted Batkin, president of the Citrus Research Board.
The psyllid alone won’t hurt California orange groves. The threat comes when the bug lands on a tree already infected with the bacterium that causes the greening disease, also known as huanglongbing or yellow dragon disease. It will feed on the diseased tree and then carry the pathogen to nearby trees. The psyllid will reproduce -- like aphids, they are asexual and don’t need to find a mate -- creating whole colonies of citrus greening carriers.
State and local inspectors are tracking the bug, hoping that it doesn’t find a citrus tree already infected with the disease, which has no cure.
Experts are almost certain one or more infected trees are out there, probably innocently spirited past airport or U.S. Customs security into Southern California by an orange- or grapefruit-loving visitor from Asia, Florida or some other locale.
Protecting the crop has implications that reach far past the state border.
California supplies about 85% of the United States’ fresh orange crop and nearly all of the domestically grown lemons. The Golden State also ships a third of what it grows overseas, a lucrative source of exports at a time when the nation has rung up a huge foreign trade deficit.
“I toured the groves in Florida where the disease is now all over the state, and they are taking out thousands and thousands of trees and burning them,” Gless said.
“They are doing it six days a week.”
Citrus greening has already killed tens of thousands of acres of trees in Florida and Brazil and wiped out entire citrus industries in China, India, Saudi Arabia and Egypt.
Gless and some agriculture analysts believe that without a cure, the disease will kill off Florida’s orange juice industry within five years. Inspectors also have trapped psyllids in Hawaii, Texas, Georgia, Alabama, South Carolina and in Louisiana, which is the only other state besides Florida where the insect is known to carry the disease.
Growers and agriculture officials want California residents to report anything odd about the citrus trees in their yards. They want to reach the tree before the psyllid does. And if the psyllid is already there, they want to destroy the tree and eradicate the colony before it spreads the disease. Homeowners will get a replacement tree and don’t have to fear giving up backyard oranges or lemons, Batkin said.
Homeowners and commercial landscapers who believe they may have spotted the insect or a diseased tree should call the California Department of Food and Agriculture’s exotic-pest hotline at (800) 491-1899. More information can be found at www.californiacitrusthreat.org.
Researchers at UC Riverside, UC Davis, the University of Florida and other institutions are scrambling to find better ways to detect the disease in its long latent stage and control the pesky psyllid population, Batkin said. They hope to eventually discover a method to cure or inoculate trees.
“These pests have a way of figuring out how to survive. The tomato psyllid moved into California from Mexico some years ago and now has walked up all the way to British Columbia,” he said.
Researchers believe the psyllid could find its way into Riverside and Orange counties before the year is out.
Every psyllid found in California -- more than 500 at last count -- has tested negative for the disease, to the relief of agricultural officials and citrus farmers. The negative tests so far have provided the industry with time to find a solution to one of the most vexing diseases in modern agriculture.
Although California farmers have been able to vanquish various species of fruit flies and phylloxxera, an insect that once ravaged the state’s vineyards, the methods used to control previous threats are largely ineffective in stopping citrus greening.
Researchers have not been able to develop a disease-resistant tree or rootstock.
There are no effective parasites or predators to use against the psyllid population. And growing and releasing sterile psyllids -- a successful way to control fruit flies -- will have no effect because of the bug’s ability to reproduce asexually.
California farmers are spending about $3 million this year on tracking, testing and research to fight the disease. Gless’ share, paid through an assessment on each carton of citrus fruit he sells, jumped by $72,000 this year to $180,000. It will rise again next year, and Gless has voted to allow his share of the assessment to go as high as $324,000.
“You will assess yourself all you can,” Gless said, “because if you don’t you are done anyway.”
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