News Release Distributed 08/16/10

Louisiana citrus growers need to be on the lookout for sweet orange scab of citrus caused by the fungus Elsinoë australis. The disease recently was found on a satsuma tree in Orange, Texas, about 3.5 miles west of the Louisiana border, according to an expert with the LSU AgCenter.

Previously, this disease had only been reported in South America.

“This disease differs from the citrus scab that we typically see on satsumas primarily in terms of its host range,” said LSU AgCenter plant pathologist Don Ferrin.

Citrus scab commonly occurs on lemons, tangerines, grapefruit and satsumas and rarely occurs on sweet oranges, Ferrin said. Sweet orange scab occurs primarily on sweet oranges, tangerines and satsumas.

The scab presents little problem, Ferrin said. “It’s mostly cosmetic, but it affects ability to sell fruit – the sweet oranges – for fresh market. It can be controlled with fungicides applied at and shortly after bloom.

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service-Plant Protection and Quarantine began conducting a survey for sweet orange scab within a 1-mile radius of the infected tree in Texas this past weekend, Ferrin said. They will begin to check citrus for the disease in Calcasieu Parish this week.

“If you find scab on citrus, particularly those in the western part of the state, contact your LSU AgCenter parish office,” Ferrin said. “They will send samples to the AgCenter’s Plant Disease Diagnostic Clinic. We will forward them to the USDA lab in Beltsville, Maryland, for identification.”

Rick Bogren