Alternaria Brown Spot
Pathogen
- Caused by the fungus Alternaria alternata
Leaf Symptoms
- Initial small brown spots that develop yellow halos
- Lesions expand into circular or irregular shapes that can cover a large portion of the leaves
- Badly affected leaves fall off
Fruit Symptoms
- Start as small dark specks and develop into either large black lesions or corky eruptions
- The eruptions can fall off, leaving craters on the fruit surface
- Badly affected fruit will drop
Varieties Affected
- Affects Dancy tangerine, Minneola tangelo, Murcott, Orlando tangelo, Nova tangelo, Lee tangelo, and Sunburst tangerine
- Does not affect oranges; may affect grapefruit if located next to highly infected tangelos or tangerines
Learn more: A Guide to Citrus Disease Identification
Management
- Commercial grove management practices are reviewed and updated annually in the Florida Citrus Production Guide: Alternaria Brown Spot
- The Quick Reference Guide to Foliar Fungicides is updated annually and available as a downloadable PDF.
- The Citrus Copper Application Scheduler is a tool available to assist in scheduling copper applications based on current copper residue levels.
