dried up leaves on new growth

[lx574]

Bubba kush feminized from Seedsman. It's in it's third week since seed. I am using main-lining combined with LST this time. Some of the new growth leaves are looking fully dried. I first noticed it during my 2nd topping, I went ahead and topped anyways and defoliated the dried up leaves. Again saw another leaf that's kinda shrivelled up. It's the new leaf that's showing this symptom, the older fan leave are looking healthy. Need your suggestion please.

[Fjeff]

Try this

[Tersky]

Usually when i have leaf deformities like that it is a root or ph issue tho some deficiencies can act like that too. That said i have some questions. What is your medium? it looks like straight coco which makes it hard for plant to breathe but easy to overwater in early stages. Cannabis plants need a good draining aerated medium. If i were you i would add perlite the next time you grow or repot. Second, did you wait until the 5th or 6th node to top? If not that can stress the plant and stunt growth. Dont think that this is causing your issue but just a tip from someone who mainline and quadline's all my plants. The reason to wait until the 5th or 6th node is by that time they are considered mature enough for HST like topping.