Don't know about all of that.But I do know that Physan 20 sprayed in the crowns has sure saved a lot of worry about crown rot for me.I have a small greenhouse w/all types of orchids in it.When I water it is impossible to avoid getting water in the crowns of my paphs,phrags and phaelionopsis.I have for a long time sprayed physan 20 directly in the crown and sometimes in leaf joints to prevent it and it has worked great!No crown rot here.
Hope this helps.I have to buy mine thru the net,mailorder.Can't find it around here.