Check your ph level. Looks like too much limestone or something that is washing away it's color. (IDK) I recently have been spraying mine with cool refrigerator water with a teaspoon of milk. They seem to love it! Stop when flowering bc mold will set in.
I have a kush that has that same "withered leaf issue" I never figured out what it was and it definitely stunted the plant. Make sure you aren't under watering or overwatering and check the ph of your nute solution...you could try googling it too.