Outdoor mystery

WTF? I've been feeding 1100 rpm at 6.5 in promix and flushing every 4th feeding. This started with whitish spots on lower middle leaves and then turning the leaves yellow then brown and dying. Not sure if it's some sort of fungul problem but it hasn't affected bud development or bud leaves. They are 3 different strains but all have the same issue. Any help would be appreciated.

Anybody?

I have the same issue but on much large plants and it didn't get to the extent ur plant have, I've had a lot rain here and my grow is surrounded by plants with leaf septoria. This is my first year growing organically so I know I've been behind on ferts since the plants started flowering thr soil got low and I waited to fertilize to be sure they had used evrrything up for sure. So when these spots showed up I fed proper nutes and sprayed with green cure. The problem has either completely stopped or slowed to the point I haven't seen it progress over the last week and half or so. Wish I could tell u what helped them but I'm not sure I defolated all dead or dying leaves to hope whatever it is its under control for the rest of flowering

What is weird is that the buds and bud leaves are relatively unaffected. Another note is I haven't had a real issue with any botrytis.

Did this start during end of August ?

Look at the underside of your leaves. Looks like pests to me. Just a guess.