hey im concerned is there anything wrong withthese or just natural?

the whole plant itself is fine but the bottoms are turing yellow at the end and curling up do i just trim it?

those tips are a pretty good sign of nute burn, but also ph diff can fool you also. are you feed them and whats your ppm. at that size your ppm should be close to zero. dont cut anything, what kind of system are you using. if those tips dont get any worse i would not do anything. but if they get worse flush and check your ph run off. also when you flush use plain ph`d water. and give it a week before you feed. i think your doing fine just keep an eye on the ladies and you`ll be good.