American Tar Spot
MODERATERhytisma americanum
Overview
American Tar Spot observed in the wild. Research-grade iNaturalist observation.
- Type
- Fungus
- Severity
- MODERATE
- Source
- iNaturalist
Symptoms
Geographic Spread
Treatments
Fungicide Application
Apply systemic or contact fungicide at the first sign of infection. Repeat applications may be needed during wet weather. Follow label rates and timing.
Sanitation and Pruning
Remove and destroy all infected leaves, branches, and fallen debris. Improve air circulation by thinning dense canopy growth. Sterilize pruning tools.
Soil and Moisture Management
Ensure proper drainage, avoid overwatering, and apply mulch to reduce soil splash. Many fungal pathogens thrive in persistently wet conditions.
Recommended Products & Tools
Helpful supplies for managing American Tar Spot. Always read and follow label directions, and confirm a diagnosis before treating.
Broad-spectrum protectant for many fungal leaf and bark diseases.
Preventive spray for needle cast, leaf spots, and blights.
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Frequently Asked Questions
What is American Tar Spot?
American Tar Spot observed in the wild. Research-grade iNaturalist observation.
What are the symptoms of American Tar Spot?
Where is American Tar Spot currently found?
American Tar Spot is currently active in Missouri, Michigan, Minnesota, Ohio, Massachusetts, Indiana, Illinois, New York. It has been reported in 8 total states across the United States.
How do I treat American Tar Spot?
Treatment options for American Tar Spot include: Fungicide Application, Sanitation and Pruning, Soil and Moisture Management. Treatment approaches may include chemical, biological, cultural, and mechanical methods depending on the severity and context.