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Citrus Health Response Program |
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Sweet Orange Scab
On July 23, 2010, the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the detection of sweet orange scab (Elsinoë australis) on lemon and tangerine trees on a single residential property in Spring, Texas, near Houston. This is the first confirmation of sweet orange scab in the United States. Since that detection, APHIS has confirmed the disease on citrus trees (sweet orange, grapefruit, and other citrus species) on four other residential properties in Harris County and on Satsuma mandarin trees on a small farm in Orange County.
Sweet orange scab is a fungal disease of citrus caused by Elsinoë australis (Bitancourt & Jenkins) that results in unsightly, scab-like lesions developing on fruit rinds and, less often, on leaves and twigs. The damage produced is superficial and does not affect internal fruit quality. The disease mainly attacks sweet orange and tangerine varieties, disfiguring the fruit and making it a potentially significant problem for the production of unblemished citrus fruit for the fresh fruit market. It also can be found on other citrus varieties, including grapefruit. Infected fruit are more likely to drop prematurely. In addition, the disease may stunt young citrus seedlings. Sweet orange scab is spread slowly by microscopic fungal spores that are produced in the scabs. Trees are more susceptible to infection when there is new shoot growth and the petals begin to fall. As the growing tissue matures, it becomes less susceptible. Spores can spread the disease to susceptible plants if there is a sufficient level of moisture in the environment. The fungus can live through the winter in the tree canopy on limbs and on fruit that were infected during the previous season. Symptoms of the disease can be detected visually at any time of the year. The disease produces symptoms within a few days to 1 week.
It does not pose a threat to human health.
News and Information
- APHIS Revises Approved Packinghouse Procedures for Sweet Orange Scab (Elsinoë australis) (8/19/11) (PDF; 17 Kb)
- APHIS Adds Conditions to Allow Fruit Movement into or through States Regulated for Sweet Orange Scab (Elsinoë australis) (4/18/11) (PDF; 52 Kb)
- APHIS Revises Federal Order for Sweet Orange Scab (3/23/11) (PDF; 78 Kb)
- Quarantine Areas Established for Sweet Orange Scab (Elsinoë australis) (PDF;
112 Kb)
- APHIS-Approved Fungicides for Elsinoë australis, Causal Agent of Sweet Orange Scab For Use in Plant Nurseries (PDF; 43 Kb)
- APHIS-Approved Packing House Procedures for Elsinoë australis, Causal Agent of Sweet Orange Scab (PDF; 31 Kb)
- The Significance of Citrus spp. Fruit as a Pathway for the Introduction or Spread of Elsinoë australis, the Organism that Causes Sweet Orange Scab Disease (PDF; 266 Kb)
- Comments on the PRA will be accepted until March 22, 2011. Comments may be submitted via email to: Deborah.L.McPartlan@aphis.usda.gov
- USDA Confirms Citrus Disease in Texas and Louisiana
- Sweet Orange Scab - door hanger (PDF; 1.83 Mb)
- PPQ Presentation: Exotic Pest Alert - Elsinoe australis - Sweet Orange Scab Symptom Recognition Training (PDF; 750 Kb)
Scientific Information
- Field Identification Guide for Sweet Orange Scab (Elsinöe australis) (PDF; 936 Kb)
- Technical Working Group (TWG) Report Sweet Orange Scab (Elsinöe australis), August 2010 (PDF; 131 Kb)
- Pest Not Known to Occur in the United States or of Limited Distribution, No. 29: Sweet Orange Scab - USDA-APHIS-PPQ-BASS (PDF; 619 Kb)
- Pest Assessment: Sweet Orange Scab, Elsinoë australis (Bitancourt & Jenkins) (Myriangiales: Elsinoaceae) - USDA-APHIS-PPQ-CPHST
- Sweet Orange Fruit Scab Caused by Elsinoë australis - A. A. Bitancourt & A. E. Jenkins - 1937 Journal of Agricultural Research Vol 54(1):1-18 (PDF; 4 Mb)
- Sweet Orange Scab - Plant Pathology Circular No. 228 - Florida Department of Agriculture & Consumer Services
- Data Sheets for Quarantine Pests: Elsinoë fawcetti and Elsinoë australis - CABI and EPPO
- Sweet Orange Fruit Scab - Pest & Disease Identification Library - Australia Plant Biosecurity
Survey
- Map: Sweet Orange Scab Positive Detections (PDF; 373 Kb)
- Detection and Delimitation Survey Methods for Elsinöe australis (Sweet Orange Scab of Citrus) (PDF; 1.07 Mb)
Other Citrus Diseases
Report a Pest
To report a pest, please visit to APHIS web site at: Report a Pest
