The PK 13/14 is only meant to be used during a very short period of time. Typically around the 6th week of flowering, and only for 2 to 6 feedings in total.
Flowers shift from a setting and building phase into a swelling phase. During this period of time when the plant is changing phases it is in need for phosphorus and potassium. Timing is the key and this will minimize the "lag" and maximize the speed of switching to vigorous swelling.
No one can do anything about those leaves. They are 100% completely dead. They could have died of anything given the pictures that we have to go on because they are so far gone. But, if you've been running the pk 13/14 the whole time then that is probably a contributer. Also, your EC seems REALLY high, especially of the A+B, the max EC I'd use is about 1.8. Even that is only for a short period of time during flowering.
Without seeing more of the plant and leaves in the midst of being sick then I think the problem is over feeding. My advice is to lower the EC of your solution a good 0.4 to 0.5 so that you're just under 1.8 EC. Also, stop using the PK 13/14 until you're in the 6th week of flowering. Flush the media and establish a fresh buffer if the problem continues after 1 week.
pk13/14 is ment for earlyer on in flowering just look at jberry response to one of my post's
and this is what my plants looked like
View attachment 1244754
JR what PK ratio you useing?
hi guys this is what info i already got off this thread
PK 13/14
i use it for almost 3 weeks...at 4 ml per gallon for the most part...
i start using it a few days after the flowers develop a bunch of pistols and stop when the nugs are finished linking together... by week 6 im done using it.
the plant only needs the pk for around 7-10 days, but to make sure i give it on the exact 7-10 days it is needed, i start early and end late... and canna assured me it wouldnt have any ill side effects...
i still pump it up to 6ml per gallon during the 7 days that i suspect to be the pk sweet spot.
it depends on how long your flower time is also... if you had a 12 week flower time, than you wouldnt want to use it until like week 8 or something like that.
i believe it calls for around 6ml/gal. If i added 6 ml/gal and my regular base nutes it would be some crazy 2000+ppm. What i've always done is cut my base nutes in half, water at 2ml/gal first time, 3 ml/gal 2nd time, 4.5ml/gal 3rd time.
PK tends to be best used in a 7 - 10 day window starting about the time you see first flower formation. This typically, on an 8 week flower response group, to be about 5 weeks before harvest or 2-3 weeks after flower initiation (not light change). Adding it early will not advance or benefit flower initiation, only the amount of dark the plant sees will initiation flowering. Adding too early could result in phosphate accumulation and ratio issues involving Ca and Mg
hope this helps
lates