Rust on mint/ peppermint plants is a fungus. You'll need to remove all infected plants and destroy them to prevent it from infecting your whole plant. If you have other mint plants nearby, quarantine the infected one.
To prevent rust in the future, water your plants at the soil level. Watering plants from above and letting water stand on their leaves is how the infection develops.
Rust on mint/ peppermint plants is a fungus. You'll need to remove all infected plants and destroy them to prevent it from infecting your whole plant. If you have other mint plants nearby, quarantine the infected one.
Is your plant outside or indoors?
Here's a complete list of how to mitigate the infection: https://www.hunker.com/12598788/how-to-get-rid-of-mint-rust
To prevent rust in the future, water your plants at the soil level. Watering plants from above and letting water stand on their leaves is how the infection develops.
Hope this helps!
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