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Sweet orange scab found in Louisiana

December 23, 2010

Agriculture and Forestry Commissioner Mike Strain, D.V.M., said new federal citrus quarantine orders have been set for Louisiana, Texas and Mississippi citrus growers after the presence of sweet orange scab fungus (Elsinoë australis) was confirmed in those states.

A federal order from the Animal and Plant Health Inspection Service (APHIS) quarantined the three states to protect other citrus-producing states and United States international trading partners.
Strain said it is the first time the fungus has been positively identified in Louisiana citrus and is very similar to citrus scab (Elsinoë fawcetti) which is common in the Gulf South. Based on discussions with Texas plant health researchers who first discovered the disease, it is believed that sweet orange scab may have been around for up to 10 years.  Recent development of laboratory protocols provides the ability to distinguish it from the more common citrus scab. 
The disease will not affect the movement of most Louisiana citrus fruit but commercial packinghouses will have to include a fungicide treatment for scab in their packing procedures.
Citrus nursery stock from the quarantine areas that does not display disease symptoms during inspection can ship to all non-citrus producing states after application of a fungicide.
Sweet orange scab is a fungal disease that results in scab-like lesions developing on fruit rinds. The damage is superficial and does not affect internal fruit quality but can impact fresh fruit marketing. The pathogen can be spread long distances by movement of citrus nursery stock and other plant parts.
Louisiana citrus growers are already quarantined for Asian citrus psyllid.  Protocols have been established to control the spread of this insect.
The majority of Louisiana’s citrus production area is located in Plaquemines, Lafourche and Terrebonne parishes. The state crop’s gross farm value was $9 million in 2009, according to the LSU AgCenter.
The commercial citrus growing states are Louisiana, Texas, California, Arizona, Hawaii and Florida.