I would not spray past 10 days in flower. Sulpher is probly your best bet far along into flower, it should slow it down. Spray your next batch of babies with the e20 or bayer. The reason I don't use sulpher is for 2 reasons 1. It does not work even half as well as the other options if used as a preventitive before the issue even arises. and 2 its a pain in the ass for me because my 2 rooms share a ventilation system so I have to shut down both rooms for 4-5 hours twice a week for it to be effective. Then air them out it turns into an all day job.