burnt tip

Hi, I got some discolored and claw leaves and I'm not able to understand what's really going on: Light burn? Wind burn? too much nutrients? my fabric pots are dirty and I was thinking that this could block oxygen transpiration making my leaves to curl. -9 of 11 weeks of flowering -temps 78...

What does the spotting and burnt tips signify? My girls are 6 weeks old. The spotting is on the older fan leaves. The burnt tips is just on one leaf so far.. Could be light burn.