I am questionable about your irrigation system, i understand if you are out of town but while you are home i would suggest taking it out and just watering when soil is dry, looks like you could use some phosphorus in those plants. I would also up my ph of watering nutes to 6.5 - 6.8 unless your soil runoff is still in the low 7's. I have used mollasses in my soil grows as well sometimes through the whole life cycle. And have had excellent results. ( you should be careful with mollasses because some have magnesium and iron which is ok but those are micronutrients and you will need less of these nutes than you think but i always used more than you do anyways so probably not your problem. Before i added any nutes to a plant that looks like that is to flush really well and dont add anything else until soil is dry, then start your nutes over from scratch slowly increasing the dose to you find the dose that your plant likes best, then once you have that down alternate with plain water.