Howdy 305mclovin, What does the under side of the leaves look like (possibility of bugs)? What is the growing environment, growing media, air and or water temperatures, nutrients, and how old are the plants?
It could be one of (or combination of) many different causes, pH imbalance, nutrient deficiency, or bug infestation. More information is needed in order to make a S.W.A.G.(scientific wild assed guess! LOL).