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Fungus halts Texas citrus shipments

by Chip Carter | November 23, 2010
Texas citrus growers have voluntarily placed a temporary hold on shipping to other states as they deal with an outbreak of sweet orange scab first reported Oct. 12 in The Produce News.

Texas growers voluntarily halted citrus shipments to other states Nov. 4, and the ban was to be lifted Nov. 19 but has been extended indefinitely.

Ray Prewett, president of Texas Citrus Mutual in Mission, TX, said that the voluntary quarantine was a good-faith effort by the Texas industry to investigate the infestation further before potentially putting other states at risk.

The U.S. Department of Agriculture's Animal & Plant Health Inspection Service confirmed the presence of Elsinoƫ australis, or sweet orange scab, in Texas and Louisiana in August. It was the first time the fungal pathogen had been detected in the United States, though it is prevalent in South America, Fiji and Samoa. Infected citrus trees were found on residential properties in Harris and Orange counties in Texas, and in Orleans Parish in Louisiana. The pathogen results in scab-like lesions on fruit rinds and sometimes on leaves and twigs; the damage is superficial, does not affect quality or taste, and poses no threat to humans, but infected fruit may drop prematurely and the disease may stunt citrus seedlings.

Even though confirmation of the outbreak did not come until August, researchers believe the initial infection in Texas took place in June. Since then, the fungus has been found in Willacy, Cameron and Hidalgo counties in Texas' Rio Grande Valley, as well as in some research orchards.

Texas shippers are working with APHIS to determine if the fungus poses a threat to other growing regions. Sweet orange scab is rare enough that most of the literature regarding it is woefully out of date. Mr. Prewett said that the most recent scientific study Mutual could find was published in 1937.

The temporary quarantine will affect California more than other states because Texas ships about 25 percent of its orange crop to the Golden State this time of year.

"The early detection of this disease clearly demonstrates the effectiveness of the Citrus Health Response Program," said Rebecca Bech, deputy administrator for APHIS' plant protection and quarantine program. "We have taken swift action by issuing emergency action notifications requiring that fruit, leaves, branches and other plant parts remain on these properties to prevent the spread of the disease. We are communicating closely with our partners in Texas and Louisiana as we continue to survey to determine the boundaries of the infected areas."