ash rust in Minnesota
MODERATEFungus
ash rust is currently active in Minnesota. Watch your susceptible trees closely and act early.
About ash rust
Found on an Ash tree. Credit to @andrewcannon for noticing that this Ash Rust specimen is hosting a parasitic Tuberculina fungus (lilac colored) and larva of a Mycodiplosis midge (orange colored). I will link the two associated observations.
Symptoms to watch for
Treatment options
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 ash rust. 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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Need help with ash rust in Minnesota?
Connect with ISA Certified Arborists serving Minnesota:
Browse all Minnesota arborists →Frequently asked questions
Is ash rust in Minnesota?
ash rust is currently active in Minnesota. Watch your susceptible trees closely and act early. It was first recorded here on July 30, 2026.
What does ash rust look like?
How do I treat ash rust?
Options include: Fungicide Application, Sanitation and Pruning, Soil and Moisture Management. Confirm the diagnosis before treating, and consider a certified arborist for high-value trees.