Physan 20 vs Thiomyl?

[vlhart]

Hi guys--

I don't know much at all about fungicides and insecticides and the like, so I'm wondering how, in general, you go about using certain ones.

Specifically Physan 20 and Clearys Thiomyl. These are the two that it seems people use the most. I've recently purchased both and am wondering how people use them. When do you use Physan 20 (on a plant, not just to sterilize surfaces/tools) and when would you use Thiomyl? How interchangeable are they? Do you use either of them preventatively?

And more specifically: I just got a Tolumnia red berry that appears to have a mild case of guignardia/"Thai disease," and an otherwise very healthy-looking Dendrobium micro chip that has one or two well-defined black spots on the leaves. Wondering how to treat both.

Thanks for any tips or advice! I feel like I'm on here asking after a new disease or pest or "spot" each week...Of course I'm buying a new plant just about every week...