cheech I've burned at 3 1/2 weeks into flower on a 10 week strain with no problems.

It's been awhile, but I think I burned for 3 hours at the beginning of their dark cycle.

There was no adverse effect on the quality of the flowers.

I would be nervous burning much later into flower though.

good luck!

Cheech: I have burned sulfur daily, for two hours during the dark cycle, through the first 3 weeks of flower with never a hint of sulfur taste in buds harvesting at 7 to 8 weeks. But those were/are preventative measures. For an active, bad case like you have I'd burn sulfur nightly for 4 hours or more for the next two weeks. If anything extend your flower period as long as possible to clear out any possible sulfur taste. Others are might disagree but your buds/plants are going to grow so much after you stop burning the sulfur I doubt it will effect taste. Just my opinions based on experience.

Man it's been a while... This thread popped up in a google search for sulfur burning, lol. Just wanted to let people know how careful to be if you spot pm. That harvest was trash, maybe got 3 lbs of pm covered buds. I burn sulfur and run a dehumidifier in flower now. Got rid of the chronic.. The donk was way more resistant. I hope this upcoming donk run goes well with the regular sulfur burns and 55% humidity at night 65% day. I'd like to see no pm this run.

2 years ago I put in 60 grams of sulfur in my burner. Each day I burn for 5 minutes, 1 hour before lights on, 1 hour after. Never had pm, taste is excellent. I run perpetual, and never stop, even for a day. btw, I still have about 1/3 of that sulfur left.