Redlands citrus grower Wes Ems walks through his
grove on Wednesday. Citrus growers are keeping a
lookout for a citrus disease that could wipe out groves
in Southern California. (Al Cuizon/Staff Photographer)

http://www.redlandsdailyfacts.com/sanbernardinocounty/ci_11574896

Insect poses dire threat to citrus
John Weeks, Staff Writer
Posted: 01/28/2009 04:19:26 PM PST

An apocalyptically dangerous citrus pest, advancing northward from Mexico into the Southland, is causing such alarm here that agriculture officials and commercial growers are asking for the public's health in watching out for it.

"This could be the death knell for our citrus industry," says Bob Knight, founder of the Redlands-based Inland Orange Conservancy. "It's the most serious threat, next to development, that we've ever faced."

The Asian citrus psyllid is a tiny insect that carries the fatal bacterium that causes Huanglongbing (HLB), or citrus greening disease.

"It is the most serious citrus plant disease in the world and once a tree is infected, there is no cure," says Allan Lombardi, chairman of the Visalia-based Citrus Research Board. "HLB has already destroyed citrus fruit production in various parts of the world, including domestically in Florida, where the industry is now in rapid decline."

Since 2005 the psyllid has ravaged millions of acres of groves throughout Asia and the Middle East, the Caribbean, South and Central America, and the southern United States from Florida to Texas. In July of last year the bug hopped the Mexico-U.S. border at Tijuana, and now has advanced to northern San Diego County. Stepped-up checkpoints and quarantine efforts have been put in place both in San Diego and Imperial counties.

Now, the Inland Empire is seen as the last line of defense in terms of preventing the psyllid from overwhelming all of Southern California groves and threatening the state's $1.2 billion citrus industry.

Experts stress that the psyllid is as likely to be found among the hundreds of thousands of citrus trees in the back yards of homeowners as in the orchards of commercial growers.

"We have what we call `party trees,' where a large infestation of insects of all ages and stages of development are clustered in a single tree," Knight says. "Any single tree can become that tree. Any single tree in anybody's back yard can become the `Typhoid Mary' tree that wipes out our citrus industry."

Homeowners are urged to inspect their citrus trees regularly. The psyllid is a small, brownish, aphid-like insect, one-eighth to one-sixteenth of an inch in length. It feeds on bud shoots and the undersides of leaves, and while feeding it adopts a distinctive tilted stance, with its head down and its rear lifted at a 45-degree angle.

The insect deposits waxy tubules of waste as it feeds, and also emits a mist of so-called honeydew that encourages the growth of sooty mold on leaves. The females lay their eggs, almond-shaped and yellow/orange in color, on the tips of growing shoots and in the folds of leaves.

Even insects that do not carry the HLB bacterium cause damage to trees, but it is the carrier insects that kill trees. Trees infected with HLB develop symptoms that include stunting, sparse foliage, mottled leaves, and excessive leaf and fruit drop. The diseased trees produce hard lopsided fruits that remain green, or partly green, with bitter juice and flesh.

"Citrus greening is one of the most devastating diseases of citrus in the world," says Elizabeth Grafton-Cardwell, research entomologist and pest management specialist at the University of California, Riverside. "If you suspect that you have trees infected with citrus greening, contact your local county agricultural commissioner's office."

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The numbers to call:

- San Bernardino County Agricultural Commissioner John Gardner, (909) 387-2115, email.

- Riverside County Agricultural Commissioner John Snyder, (951) 955-3045, email.

- California Department of Food and Agriculture, (800) 491-1899.

Wherever psyllid infestation is discovered, regulatory steps include destruction of infested plants, insecticidal treatment of surrounding plants and quarantine of the area.

For more information about the psyllid and HLB, visit www.californiacitrusthreat.org.
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FRESH ORANGES

The Redlands-based Inland Orange Conservancy is a nonprofit cooperative that promotes the eating of local citrus by local residents to help local growers preserve their groves. Oranges are fresh-picked and distributed to various community locations for pickup by members. The spring navel season has just started and continues through April 19. For membership information, call (909) 794-4484 or visit www.inlandorange.org.