When you water if you use a sprayer I've found it gets on the lower leaves and burns them. But the bottom leaves die off as they get less light as the plant grows.
It looks like nutrient burn....or possibly a ph fluctuation due to nute lock.....if it were indoors i'd cut back on the fert and flush the medium....how to do this outdoors i don't know i imagine that you just add lots of water.....when you do it indoors the water comes out a yellow piss like colour.....and you notice a difference within 12 hours.....hope that helps or someone who knows more has a better idea.....Peace out.....Sid
hold off fertilizing for a few weeks. You must leech all the chemicals out of the soil before you start again. Do this by simply watering the fuck out of the plant. Once a day should be sufficient. Then you can start with the bloom ferts in a very mild solution. I'd say 1/4 strength once a week.