fatass
Member
I just checked the "Marijuana Garden Saver" book which has a similar picture in the PH problems section - better check your PH
It looks like powdery mildew - my "The Church" which is growing outdoors had it in big scale
The best thing you can do to get rid of it is to use neem oil.
Water it once with 5% solution of neem oil and they will be gone and the plant will be protected for 4 weeks
You can also spray it with 10% solution - it will kill them instantly - but don't do it instead of the watering solution.
powdery mildew can easily spread to the other plants so I would water them with neem solution too.
Neem solution does no harm to the plants - you just need stop using it 3 weeks before harvest