In the last few days, my ageratum has started yellowing and some of the leaves wilting and dying. It doesn't appear to be spider mites but could it be some form of blight? All I can think of is to try a shotgun treatment of Garrett juice plus garlic pepper tea and cornmeal juice and hope I solve the problem with one of those methods. Any thoughts?

Ben in Rowlett

Make sure the bed is draining well. Other plants are still showing a light color due to the cool weather and trace minerals not getting into the plants easily. Might try some greensand.