Cod_Fish_Joe commented week 17 0 second from now
Im no guru, but It looks similar to what happened one of my previous grows. I figured it was to high a salinity in the soil from feeding at to high an EC/PPM, combined with under watering. This lead to dry spots in the pot, and because the soil was so salty, it was starting to wick moister from the plant.
I had it pretty bad though.
Just a thought.