Marijuana leaves are turning brown

A question from a fellow grower:

rt here are some pictures of my plants the leaves are turning brown can’t figure it out can u give me any ideas on what’s wrong I switched to 400 watt hps rooms 80 degs.humidy is 50 water with miracle grow that I always use I’m stumped can u help me please

Had a similar problem a while back but didn’t find the cause. I removed the “infected leaves” though and the plant made it through flowering without any problems. Think it could of been the extreme cold weather at the time but have no idea really.

Does that cup have drainage holes?

Looks to me like the plant is drowning due to water puddle in bottom of cup.

Plant also has got to be root bound.