ok first there is going to be a lot of information we need.

what kind of light are you using. you say your using florescents what are the watts and the luminessents?

when plants start off they dont really need all that much nutes in fact starting off with none is best. the lower leaves will die off from my experience but thats just the round little ones at the bottom. as for pesticides do you know for sure that there is anything on them? i mean why poison anything if there isn't a need.

how often are you watering, do you have it in an enclosed areas? what is your air flow like? how many plants are we talking about here?

got a picture of the plant/grow room?

Im interested to see what exactly is going on here. sounds a lot like my first grow.