Oren wrote:
On Fri, 14 Jul 2017 13:42:32 -0400, "Kurt V. Ullman"
wrote:

Have some things on my yard that I am not sure what it
is. I have
gone to two garden shops and got two mutually exclusive
responses.
After rains the last couple of weeks, I have a
cottony cover on
my grass (I thought originally it was stuff from the
cottonwood or
some weed sticking to the wet grass (see picture).
However, soon I
realized that the grass in the area was turning brown in
roughly the
outline of the cottony cover. One guy suggested fungicide
and
another just thought I should fertilize and it would come
back.
Any suggestion?
http://imgur.com/M3roAaC
http://imgur.com/3MsIWYL

_Cotton-Like Fungus in the Grass _

http://www.ehow.com/facts_7706464_cottonlike-fungus-grass.html

"Pythium blight is a fungal disease also known as cottony
blight. This
disease affects all types of turfgrass and is most common
during hot,
humid weather. Pythium blight spreads rapidly and can kill
large
portions of grass in a short time. Powdery mildew is
another fungal
disease that affects lawn grass, especially in shaded
areas. Shade,
high humidity and and improper aeration favors the
development of
powdery mildew."

Try some aeration if the ground is heavy in clay?

I was close, I was going to say powdery mildew