It sound like you have picked up a case of bacterial leaf spot. With all the rain we’ve been getting, there are lots of diseases cropping up. The disease comes from the soil and gets splashed up into the plant were it takes hold. A layer of brown paper and then straw can prevent this from happening. Also make sure that, when you water, you aren’t compounding the problem by spray watering. More on that HERE At this point all you can do is trim away the affected leaves and flower spikes of course and hope the dry weather lets the disease subside.