Bperl, I don't like to make a definative diagnosis based on photos but I am 90% certain what these pictures show is red thread. It has been quite prevelant here in NOVA over the last 7-10 days. My techs started reporting it to me early last week, 10-20% of lawns showing symptons. Why 10-20? Disease does discriminate, curioursly in all the post on this subject no discussion on cultral practices which account for a large percentage of disease problems. Red thread can and will respond to fertilization, 1/2 lb of nirogen per k works in many cases, for the stuburn cases including those who over water their lawns (not suggesting that you do) we apply eagle fungicide in liquid mix with 4% iron and it usually goes bye-bye within 7-10 days. Red thread is so named because at certain stages it does actually look red but then turns brown and looks just like your pictures.