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Citrus crisis

Backyard lemon, lime, grapefruit and orange trees could be endangered by hard-to-see insect

This magnified photo shows the Asian citrus psyllid, which is actually the size of a tiny grain of rice, feasting on tender green citrus leaves. The insects do not eat or harm the fruit. Photo courtesy of the University of California Agriculture and Natural Resources.

It's a tiny bug the size of a grain of rice that carries a disease with a three-syllable mouthful of a name.

Asian citrus psyllids have arrived in California, and with them the risk of Huanglongbing to all counties including Santa Clara. After plaguing Florida's citrus crop since 2005 and wiping out two thirds of it, California's agriculture industry, scientists and expert gardeners are armed for a fight.

"We can't do enough to get (the risk) in front of the public," said Palo Alto master gardener Candace Simpson. She said every citrus tree — whether it's in a pot as a topiary or in an established part of your yard — is at risk.

The insect has been found in eastern Santa Clara County as well as other Bay Area counties. Those carrying the disease have been found in most Southern California counties. Simpson said the infected insects were found in a grapefruit tree in a backyard in Riverside on July 15. In September, experts found a second infected tree in a neighbor's property and just days later, a third was found about a half-mile away.

"It happens when the new growth comes out in the spring," Simpson said, the tiny "feathery growth" is food for the psyllids who lay their eggs on it as well.

The insect is considered "established" in Southern California, which means agriculture officials will contain it, but they won't be able to eradicate it.

"I believe that the CDFA (California Department of Food and Agriculture) is using a 'suppression' strategy against the Asian citrus psyllid in urban areas," said Andrew Sutherland, an adviser for the state Integrated Pest Management program in the San Francisco Bay Area. "So far, the term 'eradication' has only been used early on in the invasion and in agricultural production areas. Residential treatments are voluntary but highly recommended by the state at this time."

Officials place yellow sticky traps in trees to detect the bugs. Other than seeing the bugs, symptoms can include small, lopsided fruit, spotted or blotched leathery leaves, and waxy tubules left behind for the eggs. The bug is brown, about the size of an aphid and is generally found on leaves. It does not eat the fruit.

So far, no diseased trees have been found in the Central Valley where most of the state's citrus crop is grown. Simpson said the citrus industry is working to grow disease-resistant trees and nurseries are under strict regulations and inspection schedules.

"In order to protect everybody's ability to grow citrus in their yards, our best chance of not having the disease is controlling the insect," she said.

The problem, Simpson said, is the bug can be carried on material, for example if someone drives up here from Los Angeles with citrus fruit with leaves attached. State officials don't have any way of enforcing private transport of plant material. It's OK to move fruit, she pointed out, as long as you wash it first and don't carry the plant parts (leaves and stems) with it.

"The situation with Asian citrus psyllid and Huanglongbing disease changes almost daily in Southern California, but Northern California seems to be stable at the moment," said Karey Windbiel-Rojas, associate director for Urban and Community Integrated Pest Management for the University of California Division of Agriculture and Natural Resources.

According to the UC Davis Division of Agriculture and Natural Resources, about 60 percent of Californians have at least one citrus tree in their yard.

What to do if you find evidence of Huanglongbing in your yard?

"If I found an Asian citrus psyllid, if I saw those waxy tubules (see photos), I would immediately call the U.S. Department of Agriculture (office) in San Jose," Simpson said. They will either tell you if you could treat it or would collect those insects and ... test them to see if they had the disease."

If the psyllids have the disease, officials would put traps around the neighborhood to quarantine them. If a tree has the disease, officials would set up a quarantine, which prohibits moving any citrus nursery stock out of the area. Any fruit that is not commercially cleaned and packed must not be removed from the property which it is grown although it can be consumed there, Simpson said.

"If (your) tree had the disease ... your tree is doomed. (There's) nothing that can be done. And, Simpson emphasized, there's no need to blame yourself. "It's not your fault," Simpson said.


For more information go to If you think you've spotted the insect or signs of the disease, call the free statewide pest hotline at 800-491-1899.

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