I’d consider the Marigold in the tent as a potential culprit to the carrier. Where did you get the Marigold, it may have came from a store with the mold present nearby and housed the mold or brought the spores home? Reused, unclean/unsanitized cloth grow bag. Use of used soil. All the growth in the pot like clovers ect that you have growing with the ganj may be a culprit as well. I know you mentioned you always let random growth in the pot. It is possible that those are spreading the spores after they become infected and spreading it to the weed.