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New citrus disease found in Riverside County

Community meeting set for August 9 as agricultural officials’ begin battle.

August 4, 2017

RIVERSIDE COUNTY, Calif – A bug about the size of a gnat likely transmitted a plant disease that jeopardizes Riverside County’s $187 million-a-year commercial citrus industry. That threat and the battle against it will be the topic of a meeting August 9 with residents from north Riverside, where the presence of the disease was confirmed last week for the first time ever in the county.

A small, bare patch in a shaded area next to a well-kept Riverside home is evidence of agricultural inspectors’ efforts to battle Huanglongbing, also called HLB. Inspectors removed a tree infected with the disease and have surveyed plants within 800 meters of that spot. No other sign of the disease has been found, though officials are waiting for test results on tree samples taken in the area.

On Monday, Riverside County Agricultural Commissioner/Sealer Ruben Arroyo stood where the diseased tree was found and examined a sticky card that traps the bug that spreads the HLB bacteria. Several Asian citrus psyllids were among dozens of captured insects that dotted the bright yellow card, which acts as a lure. Arroyo, who became commissioner/sealer in March after holding that post in Kern County since 2008, said community awareness is among the best hopes for keeping HLB in check.


“This disease threatens all citrus trees, whether they are grown by citrus farmers or in residents’ backyards,” Arroyo said. “If you have citrus trees in your yard, make sure you know the symptoms of the disease and please contact county or state officials immediately if you see symptoms.”

In Florida, which has a $9 billion a year citrus, the disease was first detected in 2005 and has had devastating effects. The USDA reported in January that the orange crop forecast for this year was 70 percent lower than it was 20 years ago and 14 percent lower than last year. Fifteen states or territories are under full or partial quarantine because of the Asian citrus psyllid, called a vector because it can spread HLB.

The disease attacks trees’ vascular system but does not pose a threat to humans or animals. Leaves start to yellow, and trees begin looking sick and dropping fruit. Fruit from infected trees remains green because it never ripens. The Asian citrus psyllid can spread the bacteria when the pest moves from one location to another, feeding on citrus trees and other plants. Once a tree is infected there is no cure and it typically declines and dies within a few years.

Local agricultural officials, along with the California Department of Food and Agriculture (CDFA) and the U.S. Department of Agriculture (USDA), continue to pursue a strategy for controlling the bug’s spread while researchers seek a cure for the disease. The psyllid can range locally on its own, or hitchhike long distances when diseased trees are shipped via highways or transported in other ways. Last year, researchers led by a University of California, Riverside, scientist were awarded a $4 million USDA grant to fight the disease. To control any spread in Riverside, a quarantine will prohibit nurseries and residents within five miles of the site near Chicago and Marlborough avenues from selling or moving citrus trees or other plant material that might carry the insect.

Beyond the value of the agricultural industry, citrus is at the heart of the Riverside County region’s history. California navel oranges sprang from two parent navel orange trees, one of which remains at the intersection of Magnolia and Arlington avenues in Riverside. The trees were sent from Brazil to Eliza Tibbets in Riverside in 1873.

The August 9 meeting about the citrus greening find is scheduled to begin at 5 p.m. in the lobby of the County Administrative Center, 4080 Lemon St. in Riverside. The meeting will be geared primarily toward residents in the north Riverside neighborhood where the disease was first located but it is open to the general public.

For more information about citrus greening or the bug that spreads it, please call the Agricultural Commissioner’s Office at (951) 955-3045 or CDFA’s toll-free pest hotline at 1-800-491-1899 or visit:

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