Its costly but "Trifecta Crop Control" works, its all natural (said to be safe) and can be used up to harvest. Follow the on-board instructions.
Air flow around the girls and through them is very important, I sat up fans in the garden last year, cut everything within 18" of the ground off, pulled limbs around and tied them so more air can flow through them. After a shower shake them off to get the water out of the buds.
Good luck!