HELP Farmers! Whats going on with these plants?!

can anyone tell me whats going on with these plants? never seen anything like it the leaves start off as small spots and darkening leaf tips then get taken over by reddish/brown veins and eventually die and crisp up like in the photo. its starting to creep up to the buds but there are some healthy branches too. what should u do am i gona lose em? i use fox farm trio with silica blast and beastie bloom but have recently flushed these plants. the strain affected are grand daddy purp and purple kush. i also have bubba kush chem dawg and green kush which are lookin fine and perfectly healthy. not sure whats going on here please tell me what you think!

would root rot do this?

Your recent flushing was probably the opposite of what you needed to correct whatever feeding deficiency you have like calcium or magnesium deficiency. So you made things worse is my bet.

Feed like normal again and give some cal-mag to boost those nutrients.
They're starving.

Could be ph off too, check it.

ph is around 6.5-6.8 and never really changes. i thought as much it just struck me bc the two other kush strains i have arnt experiencing the same thing heres a pic of my green kush and bubba kush perfectly healthy... ill grab some calmag this weekend and see what happens.. im scared to keep feeding them nutes tho must be a strain deficiency then. i might decide not to keep these strains in the future

Each strain will require it's own nutrient strength, that's just how it is. If that strain needs more nutes it's because it's using them faster and may be a higher yielder than your others, it would be wrong to get rid of it yet.

na its def not one of the higher yielders ive already 86ed the GDP and if they show weak characteristics i duno if i want to keep them around anyway. look at my green kush and chem dawg i think id rather had a shite load o that!!

oh yea ok, nice.