can't ID problem with plant (pics)

I've read all the problem threads from this forum and 2 others, but I can't decide what my problem is. The leaves are cut from where I touched it to the light and burned them, but this discoloration just started yesterday am. It's mainly on this one cola, another is starting to show signs, while 2 are unaffected. I grow in soil and use fox farm liquid nutes, and have followed the feeding chart to a T. The strain is Ladyburn 1974 and is finishing week 3 of flowering. Also there had been some leaves at the bottom yellowing and dying off, but I just thought it was natural shedding because it was very slow and few. Also, the tips of all leaves are yellow to brown, but just the very tips. Any help is appreciated.

what are you using for a light and how far away from the plants are they?

It's a small closet grow with a 250W hps...and the lights are about 8-9 inches away...maybe too close?

No that is definately not too close. I thought we were looking at heat stress or light bleaching. I will get back to you.

k...thanks for the help.

magdef?

Whatever it is, it's minor. Might be tough to ID anyhow until it progresses more, I'd recommend just watching it for now.

Dont know for sure but i had some started like this and it ended up being spider mites. Problem kept getting worst till it was noticeable.. I bought some neem oil at lowes and a sprayer and it stopped. Killed mites and helped plants over all. Might be worth a try, neem oil is good for them any way.

magnesium............

i thought about Magnesium def...I don't think mites as I keep all my supplies inside an concealed from exposure. Do Fox Farm nutes have low Mag count in them?

Have had the same probs before myself also pale green leaves and yellowing lower leaves. calmag every feed and a single dose of nitrogen mono sorted everything out. easy on the nitro as you are fowering. good luck.

my problem is getting worse. Strange that it's only on that one cola mainly. However, I think the problem is nute overload. I have fed every watering, so I'm gonna flush it next watering. I'm a new FF user, and the chart suggests every watering, but the fine print says every other. I used Ecogow stuff before, but was not a liquid formula, so it became a PITA. I just swapped over to FF and let my stupidity return. I know better. We'll see if that offers improvement.

are you growing in soil? don't flush always use calmag plus when you start flowering. epsom salt alone does not work because you need calcium to absorb magnesium.