Increase ventilation, the faster you can change the air in the room with low humidity air the better. In soil, water in the morning when the lights turn on so that water can evaporate, do not water at night before lights turn off, because it will be wet. Ventilation all the time and watering early in the day will help a lot to keep humidity down, and pm loves cool humid nights with no wind. In bloom, the same conditions that favor pm also favor budrot, which sucks. This can eat a cola from the inside, turning it to brown mush, and can happen in 24 hours. Make sure you pull buds apart and back from the main stem in really dense spot, and get air in there so water doesnt get trapped.