We had a very hot summer here and in early August my grass got a few dead spots. The have spread into a very large area now a there are a lot of smaller spots that are dead also. I have put grub killer and fungus killer on it but it has not helped. What is the problem? I do not have a photo at this time.
Make sure that you use them according to the package! Sometimes it requires multiple applications to kill off pests and fungi in the soil.
Outside of this, testing and amending for nutrient deficiency or pH issues will be appropriate.
These article will offer more suggestions for your issue:
During heavy rains he floods my yard and the back end which slopes downward erodes at the grass. Is there a stronger grass to hold against the flooding?
Bahia grass, ryegrass, and rough stalk bluegrass tolerate wet soils. They perform best in shade, but you didn't mention whether the site was in sun or shade. This would be a good question for your local extension agent, who will know which grasses do well in your area.
You might consider adding a border of moisture loving perennials. This article will help:
For other ideas about how to improve drainage (such as a French drain):
s tunnel, do you still think they are dollar spot fungus?
Unfortunately, your photos did not come through. I am unable to see the issue at hand. They could, certainly, be spider holes, or several other issues. This does sound more like a spider issue, than Dollar Spot.
when grass was green it was ,green ring on green lawn
It could be fairy rings - a fungus that prevents the proper uptake of water. Here is more: