leaves crispy and curling

ok so my leaves feel crisp to the touch and meny are dieing off and falling the buds are really small and im on week 9 of flowering what am i doing wrong or messing up on heres my setup:
4x4x7ft mylar tent 1000W HPS with a 8in vortex fan
foxfarm ocean forest soil, with botanicare CNS17, bud candy, and my water ph'd to 6.0 - 6.5
the strain is master bubba kush
average day temp 70-85, night temps 50-65

the light is about 17 in away from the tops and their is a box fan circulating air around. For 9 weeks of flowering the buds are small and the leaves are all dieing will it fill in am i missing something?

I would think you are S>O>L.Flush!

How long have they looked like this? If they're at 9 weeks flower, I'd say it's time to harvest. They look like they are low on Nitrogen and the 50* temp is also pretty low. 60* would be where I would go on your next grow.

Too much fertilizer maybe. Do you fertilize with every watering?
Is that the beginning of Botrytis on the right side?

I feed every other watering, iv tryed flushing but maybe I should again, for 9 weeks its not packing much weight and is supose to be done

mine look identical to yours ! it started with the tallest plant and moved down with leaves curling up then getting crunchy and dying. i've tried everything to correct and solve the prob. thought it was a mag. def. with leaves curling up, added cal/mag with no results,tried flushing didnt help, mine were about 3-4 weeks into flowering when it started ? would love to know what you find out- am using dwc setup ,6.0 ph, keeping ppm's around 500-800 , 400w hps, good ventilation, room is around 75 degree's,

One of my blue dreams is doing the same thing. Not as bad tho mostly just the big leaves and jus a couple around some buds. It started two days into flush. Your gna want to get rid of as many dead dry leaves as u can or it can defanetely mess with ur buds. And I have 16 various strains in a room that 8Lx5Wx8H with 2000 watts hps one 1000watt hps two 400 watt lights and one 200 watt light. It's about 75-80 degrees in there when lights on and mabey 55-65 with them off. I'm using dyna bloom, pro-tekt, calmag plus, vitamin 1 with half the plants supplemented with awesome blossom and the other half of the plants with beastie blooms. And the awesome blossoms made my plants a lot bigger and they have a lot more trichomes too there just a lot more full and all around amazing.. I started the supplements after the third week in flower. B4 them 3 weeks I used cyco swell on half the plants and true blooms foliage spray on the others. Witch is a awesome supplement it increases co2 absorption and enhances flower production and side branch growth and shortens flower time. Try it if u haven't its by beneficial biological.. And I flush every ten days for 3 days doing a new flush of water every day jus to make sure it's all out b4 I put new mutes in any way could u tell me what's going on I mean I'm not new to growing but this is kinda wierd.. Most of the big leaves are either just turning yellow like there supposed to during flush but some are completely turning crispy over night mostly bigger leaves but some of the sugar leaves are now doing it.. And it's to the point that I go to take them off and they crumble in my hand!! Wtf could be happening? Oo and the triches are about 70% white 20% clear and 10% amber on this plant.. It's only the one outta 16 doing it. Can anyone let me kno if it can infect my others so I can get it outta there? Thanks and sry for the long ass msg

There isnt much to say about this, its a little to late to fix them at this point, maybe if you had caght it earlyer but sorry i dont think you can do anything but harvest.