The only real disease that troubles tarragon is rust. What you described are not symptoms of rust. I suspect it is a water-related issue. It may need a little more than you are giving it. When you water, give it a good soak, then let it dry out before soaking it again (versus frequent shallow watering).
The only real disease that troubles tarragon is rust. What you described are not symptoms of rust. I suspect it is a water-related issue. It may need a little more than you are giving it. When you water, give it a good soak, then let it dry out before soaking it again (versus frequent shallow watering).