USDA confirms 'sweet orange scab-like' disease in Florida

01/20/2011 02:00:00 AM

By Vicky Boyd

The U.S. Department of Agriculture’s Molecular Diagnostics Laboratory in Beltsville, Md., has confirmed what the Florida Department of Agriculture and Consumer Services is calling a “sweet orange scab-like disease” on three citrus samples taken from Florida.

Richard Kinney, executive vice president of the Lakeland-based Florida Citrus Packers Inc., says it’s premature to speculate what type of impact the disease find would have on fresh citrus exports. “We’re trying to determine that now,” Kinney says. “The science, to us, is pretty clear that the fruit is not a vector, but you have to look at each market.”

Although the USDA confirmed the suspicious samples as sweet orange scab, Florida’s agriculture department is calling it sweet orange scab-like because some staff pathologists have found inconsistencies within the disease, says Denise Feiber, spokeswoman for the Florida Division of Plant Industry in Gainesville. The differences make it more difficult to identify.

On Dec. 23, the USDA lab confirmed the SOS-like disease in a grapefruit sample collected from a campground near Lakeland and a bitter orange sample from a residential property in Westin, Broward County, she says.

The Broward County homeowner has since removed the tree, she says.

On Jan. 10, the lab confirmed a tangerine collected from a residential property in Sarasota County was positive for the SOS-like disease.

The owners of the positive sites have been issued emergency action notifications, which prohibit them from moving fruit, leaves or branches off the property, Feiber says.

Inspectors have completed surveys within a 3-mile-radius of each positive site. They also submitted nine fruit and one foliar sample. Results are pending, she says.

They will expand the survey out from a 5-mile radius of each positive site. In Broward County, that involves 148 properties, including a couple of citrus groves.

In Sarasota County, 210 properties will be surveyed. One citrus operation is outside of the 5-mile radius.

In Polk County, surveyors will visit 562 properties, including several groves. Of the groves, a couple are within 2 miles of the positive find.

Sweet orange scab, caused by the fungus Elsinoe australis, has been confirmed in Louisiana, Mississippi and Texas, where it has moved into the commercial citrus area.

In December, USDA issued a regulation that would allow citrus from commercial groves in south Texas to move to citrus-producing states as long as the fruit had undergone approved packinghouse treatment.

Sweet orange scab differs from common orange scab that’s widespread in Florida in that SOS only affects fruit, according to a University of Florida publication. Sweet orange scab mostly attacks all sweet orange and some tangerines cultivars.

Common orange scab, caused by the fungus Elsinoe fawcetti, infects both fruit and leaves. It is predominately a problem on many tangerine hybrids, such as temple, as well as grapefruit and lemon. It rarely is found on sweet oranges.

Several commercial fungicides are labeled for common orange scab control.

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