Thank you for the question.  What beautiful flowers you have!  You can dead head the monarda whenever you want to but some people leave the seed heads for the birds to eat during the winter and for general winter interest.

I can't tell what might be going on with the coneflower.  It might be the beginning of something called aster yellows, a disease that is different from many of our common fungal, bacteria, or viral diseases because it is caused by a tiny bacteria-like organism known as a phytoplasma.  There is no cure for this so watch your coneflowers closely for more evidence of this disease.  If you see stunted, twisted foliage, discolored petals that may be puckered and distorted or secondary flower head emerging from the primary flower head, remove the plant and discard in the trash to help prevent spread of the disease.  Read about it here  http://web.extension.illinois.edu/jsw/eb284/entry_8796/

Thank you for contacting Extension.