bud mold...oh no

hi,
what causes bud mold?
I was wondering why my Chronic plant wasn't maturing. I was at about 10 weeks flower, all the others were harvested. I trimmed all the side branches so the cola was enourmous.
I smelled it and it smelled kinda off, so I pulled the buds apart and it looked like a spiderweb of fuzzy mold in the entire cola.
what caused this to happen?

I dont' want to have the same problem next time...

High hummidity ..and unclean growing areas ..but some starian are more prone to mold then others