My Sunray has black spots on it. I'm assuming it's fungus related. It's very healthy otherwise...it has grown 2 new stems within the last 5 months which is the time I have owned it. So, I purchased some Captan Fungicide but can't seem to figure out how much I need to put in a 24 Oz spray bottle which I had planned to spray all my orchids (for the first time) down with. Can anyone help me on this? Thanks