Dennis Olivas who has a ton of orchid cred gave us this tip for an orchid that is suffering from crown rot but still has viable leaves and roots.
Pour Hydrogen Peroxide into the middle of the plant. He said don't touch it, don't cut it, don't play with it, just pour. Leave it alone (except for normal watering) for about two weeks while the center gets completely dry and turns crispy then just pick out the hard lump of center. He warned not to touch until we knew the center was completely dried or the rot would spread.
I found this website with some of the home remedies that Dennis talked about.
http://www.gardenislandorchids...
I use alcohol and I use 409 but at full strength and not mixed together.
This guy has 15,000 orchids and they are beautiful. He must be doing something right.
