Brown Patch
When: Mid-Late Summer

Appearance: Irregular shaped areas throughout the lawn

Affected Grasses: Centipede, St. Augustine, Bentgrass, Bermuda, Ryegrass, Fescue and Zoysia.

This is a fungus and should be handled as soon as the disease is noticed. It can and does spread and can sometimes take 3 or more treatments to cure.
Pythium Blight
SEASON: Summer.

Appearance:  Irregular patches a few inches in diameter that are light brown or straw color, sometimes reddish brown. In the early morning, a white, cottony fungus can be seen on the blades of diseased plants.

Affected Grasses: Tall fescue, bermuda grass, Kentucky bluegrass, annual ryegrass.

High temperatures & excess moisture.

Dollar Spot
When: Spring through fall.

Appearance: Small silver dollar-like shape, but can begin the size of a small grapefruit. It usually looks brown or straw-colored in appearance and may merge to form large patches

Affected Grasses: Bermuda, Bentgrass, Zoysia. Occasionally St. Augustine & Centipede. 

Several factors influence the occurrence and severity of dollar spot. 

Arkansas Elite Turf, LLC, Lawn & Tree Care, Hot Springs, AR