Are you sure its mold?

The reason I ask is this: I've seen mold grow as you describe, usually on a plum that has a split pit and a little air channel up near the stem into the pit, which allows the mold spores to enter. But, I've also seen white or greenish scar tissue form that is kind of mold-looking, sort of generic strands of fuzzy growth, as the plant tries to fill the void with something.

Regardless of the cause, if its very slight, I just usually trim that part off with a knife and still use the plum. Your mileage, of course, may vary, because some people are more sensitive to molds than others.

It does seem to be some kind of moldish thing. More often I find it in the riper plums. No split pits involved. Sometimes just on one side of the pit, sometimes on both.

I suppose I could let one sit out and see if it grows.

I had that on blue plums that I was drying, though don't think I ever saw any when I opened up a plum. When I just pitted and dried the plum halves, some would grow some mold. A different time I split the plums, then sprinkled them with fruit fresh and had no mold at all.

For your case, I agree with Denninmi to just remove the mold, but then I would also treat with the fruit fresh to inhibit any new growth until the plums have dried.

I'd go by a taste test. Mold tastes moldy- right?

It does taste moldy. Sort of bitter, like penicillum.

any chance of pictures?

Here's how to post them
http://forums.gardenweb.com/forums/load/hosta/msg0513322013993.html?14

Here is a link that might be useful: how to post images

I've never been able to get that photobucket thing to work.