the white patches are Powdery mildew. also the one plant seems to of stretched alot? how high is your lights and how strong is your ec/ nutrient. mack. so i've relooked at the pics, seems you have some cfl's really close to one plant, the other plant needs way more light. go and check both the plants, are thet both covered in white "ash" like patches, then they both have pm, personnally at this stage i would cut my loss, kill them both disinfect the whole growroom with a sulhur candle, then get some systhane made by bayer,and spray any other plants you have, but you can only use it in veg! this is one of many things you will learn on your journey as a a grower.next up is bud rot,have fun! lol. mack