Hello,

I’m sorry to see your bee balm is in trouble. Bee Balm is well known for getting powdery mildew. But this does not look like that.  I also thought it might be frost damage but I guess that this damage has happened more recently than our last frost.  I think that it may simply be a lack of water.  We have had little rain in the last couple of weeks and drought or insufficient water can cause leaf curl, scorching and leaf browning. Try giving the plants at least an inch of water a week to see if the conditions persists.  If it does, you could send the photos to the Plant and Pests Diagnostic Lab at MSU Extension. Go to: https://www.canr.msu.edu/pestid/  to learn how to send in a sample.

I hope this helps you to solve the problem.

Thank you for your question.