Plant leaves

My leave at the top are yellow and it gets more green as you go down the plant. What could cause this? Sorry no pics camera broken.

nute burn, deficiency, light burn? hard to tell without pics.. what stage is the plant in? how long you been vegging or flowering?

been flowering for 7 wks now. leaves are yellowing and dying like crazy.

possible iron deficiency

if it is a indica plant, then that is normal it means the plant is nearing the end, the plant is sucking the N out of the leaves!