Here is NC the snow has melted, though there is still a chill in the
air. While outside in the yard, I noticed a milky white substance on
many blades of grass. It almost looks like someone took a paint brush
with white paint and flicked the brush so that the paint spattered over
the grass blades.

Any idea what this is and how I should treat it?
Not likely powdery mildew this time of year, but more likely snow mold. See:
http://www.colostate.edu/Depts/CoopE...s/snowmold.htm
sed5555