In the Garden:
Southwestern Deserts
December, 2010
Regional Report

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Verify that you aren't sending citrus greening disease along with your fruit!

Citrus Greening Disease

The holidays are upon us and it's traditional for many backyard fruit growers to share their abundant citrus crops. Before sending fruit to friends and family, verify that you aren't spreading citrus greening disease. Also known as huanglongbing (HLB), it is the most devastating citrus disease in the world and has no cure. Infected trees produce bitter, inedible fruit, and the trees die in as little as three years. Healthy citrus trees would otherwise typically produce for 50 years, so HLB has the potential to decimate the citrus industry.

How HLB spreads
The Asian citrus psyllid (ACP), common in China and Southeast Asia, sucks on plant tissue. This damage is generally minor, but during feeding, the psyllids may transmit the bacterial pathogen that causes HLB. The tiny insects were first found in the U.S. in Florida in 1998. Since then, ACPs have spread to the Southwest: 60 of the 110 Texas counties where citrus grows and the entire state is under quarantine. Ten separate sites in Yuma County, Arizona, have identified ACPs, and these areas are under quarantine, as well as various counties in Southern California. Citrus greening disease has been identified in Florida, Louisiana, Georgia, South Carolina, Puerto Rico and the Virgin Islands.

Monitor trees regularly for psyllids and symptoms of greening disease. Texas Department of Agriculture provides photos to aid identification at http://www.texascitrusgreening.org/signs.php.

Adult psyllids feed with their heads down and the body lifted off the feeding site at about a 45 degree angle. It's a bit bizarre and noticeable, like they're hanging on during a windstorm. Nymphs are flat, yellowish-orange and have two red eye spots. Eggs are bright yellow-orange, almond shaped and laid on the tips of new growth or crevices of unopened leaves.

Symptoms of Greening Disease
Blotchy mottling of leaves
Leaf yellowing
Small, lopsided, misshapen green fruit
Twig dieback
Stunted leaves; sparse foliation

What To Do
If you spot something suspicious, report it. Find the appropriate agency in your state at http://origin-www.aphis.usda.gov/services/report_pest_disease/report_pest_disease.shtml. (Or call your County Cooperative Extension office.)

Because there is no cure for this disease, the U.S. Department of Agriculture (USDA) prohibits citrus plants and plant material from moving outside of areas where citrus greening is present and restricts the movement of the same material from areas where the Asian citrus psyllid is found.

Citrus fruit being moved from inside of a quarantine area for ACP to citrus producing areas where ACP is not present must be cleaned using normal packinghouse procedures and have a valid compliance agreement issued by the USDA. Do not send your uninspected citrus fruit. Do not receive fruit from areas where greening disease is found unless it has a compliance agreement. In Arizona, call (602) 431-8930 for more info. In other citrus producing regions, contact your state department of agriculture.


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