That is mold. Too high of humidity or too low of air circulation... or maybe a little of both. Most folks wouldn't smoke it, but if you are desperate for smoke, washing it with water might remove some of the mold/mildew,but it will still be less than desirable. Plants can turn moldy overnight. I started drying my branches in a refrigerator... it has the perfect humidity and will keep mold away as long as it is an auto defrosting refrigerator. Just lay the branches on a sheet of newspaper and let it dry for a week or two. No mold, no mildew... and it preserves the terpene profile nicely.
Ive grown for decades but still sweat the drying part... like you have found out the hard way. If it is just a bud or two, you can [probably get away with using the unaffected buds, but if they are all like that, you need to rethink your drying methods to something that has lees chance of molding up on you.
That’s ready for the garbage can or composting bin, NFG. Get air moving over the unaffected branches being dried or you’ll lose everything. If the spores are already there, it may be too late for anything...
Thank you all guys, i have some branches in a box drying, now i put a vent working so the air can flow. And i have another in a net drying with 2 pans on it so they wont get any light, just some but very low.