On Friday, July 14, 2017 at 2:31:29 PM UTC-4, 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."


Could be or it could be another fungal disease. Red thread comes to
mind, except I don't see the characteristic shriveled up ends that
wind up looking like red thread. Any evidence of that?

Whatever it is, it's fungal. And fertilizer is the last thing you
want to do with most diseases, it just makes it worse. High nitrogen,
water and high temp are what promotes it. Let it dry out, only
water right before dawn so it doesn't stay wet over night.

You can google for images of various turf fungus problems, see what
matches and what the conditions for it to develop are. Some of
these, eg red thread, are generally not serious and the grass will
survive. Others destroy the grass and can spread rapidly. Whether it's
worth treating with a fungicide is a judgment call.