Hmm not sure what that is but it looks like disease or a type of mold. If it is either you should get rid of that WHOLE bud site so it does not affect the rest of the plant. Just hack it right off. Sounds like if it was mold, the powder that came out may be mold spores and could spread to the rest of the plant. If I'm wrong please do correct me someone, but better be safe than sorry. Doesn't look like there is any fixing that type of problem. Best of luck. Gg