I just repotted an angel wing begonia that I started from a cutting a few years ago. It's been doing quite well until recently, when it started looking a little peaked. I thought maybe it needed repotting, as these begonias are heavy feeders. Well, when I pulled it out of the old pot, I found mold throughout the old soil. A white, webby-looking mold, as well as some granulated bits of I don't know what (looked like sand, but I don't think it was) and a patch of clear orange slime down in the soil. The plant itself had much less root than I expected, and no big robust roots at all. What is this stuff, and is it hurting my plant? I really love this begonia and I'll be devastated if I lose it. I plan to take some cuttings later today so that I can save something if the whole thing must be scrapped, but I'd rather not scrap the whole thing. I've read that baking soda is a good antifungal- would it work on mold, too? If I mixed some baking soda with water and watered the plant with that, would it kill off the mold and whatever else is in there doing harm?