Looks like mite damage mate. Check the underside for wee beasties. Sent from my SM-J330FN using Grasscity Forum mobile app
check out a deficiency page on the forum.... don't think that's a bug problem. whats your ph like? you feeding a lot? sativa dousnt like lots of nutes
Are these clones you took from a flowering plant? looks like it started flowering and is now revegging. As for the markings, does the mother plant have them or just the clones?
Advanced nute burn! Flush: pour 3 times the pot volume of air temp/ph'ed water allow to drain, overnight is best on the last flush add a pinch of calmag no nutes for 2-3 weeks after that feed at half strength to harvest harvest will be delayed but hey you will get some in good luck
That is not a burn . It's from VPD ( vapor pressure deficit ) and looks like you also have a late stage magnesium deficiency going on.