I had the same look on my plants and it turned out to be a pest problem. The bugs are so small you couldn't even see em with the naked eye and black spots started forming on all the stalks. I think they were Thrips but it's still unconfirmed. I used one treatment of Insecticidial Spray and the plants have seemed to have gotten better since.
look at the tips of all the leaves in the pics, they are quite clearly burned by over fert the tips are brown and crispy, id say thats more of a problem than any bugs, and i woudnt advise anyone to spray insectacides on a plant thats over 9wks into flower, unless you wanna be smoking insectacide
![Spew :spew: :spew:](/styles/smilies/spew.gif)
and adult thrips are very visable to the naked eye, its their larve that does the damage, but if you have larve doing damage you should be able to see adults lurking around.