Hi Victor, I'm new to the forum but have had Jade plants in my greenhouse for a very long time. Can't get them to grow inside the house. HA! Over the years I've had several problems with gray sooty mold which reminds me of mildew and is sticky. I have found over the years that it can be washed off with soapy water and decreasing the plants humidity keeps it at bay. I nearly lost my plant before I figured it out.
Andi

Victor, I think what you might be seeing isn't mold at all, but "Mealy bugs". (I thought it was mold on mine at first, too.) Mealy bugs are a pretty common problem with Jade plants.

You want to either spray them with a spray bottle of Rubbing alcohol (or remove the spots with a Q-tip, dipped in Rubbing alcohol) or wash them off with your sink (or shower) sprayer, several days in a row. (That gets them down the drain, instead of displacing them so they can just come back later.) I spray alcohol on mine, cuz I check them almost daily & when the Mealy bugs appear (only as often as every 3 or 4 months), I see them early on, so they're only in a small area. The alcohol doesn't hurt the plant at all.

Here's a link, for more more authoritative info on Jade plant pests. Good luck!

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