Judging by the 'stretchiness' of it, I'm guessing those leaves are dying due to lack of light. It could be hungry too, but either way, it needs more light. How does the upper foliage look?
Need little more info on setup,what's it in how many gallons,what kind of light u using,cfl's suck,u need so many of them to do same job as a hps or mh.u get smaller buds with cfl's,will be spacey,where hps with make em thick and fat.put the cfl down and step away from the grow room!!!