I found brown spots on the underside of some of my syrian oregano leaves, I think it might be Puccinia menthae. The plant seems healthy overall, but maybe not for long.
Any idea how I can fight this?
An idea: clip off the affected leaves, then drench the plant with a mixture of 30 percent milk and 70 percent water until dripping, in bright light (like midafternoon sun). This milk mixture is the an accepted first-aid intervention for powdery mildew, but I've been using it with excellent results on hollyhock rust this year. Maybe it will work on your oregano rust, too.