Using bleach to kill lawn fungus is highly inadvisable. Bleach kills fungus, but it also kills the surrounding grass and increases the soil's pH to levels so high that the soil becomes inhospitable for any plant growth. Good lawn care can kill fungus, but for faster results, hydrogen peroxide also works.
Changing watering and fertilization schedules is the most common way to kill lawn fungus. Watering the lawn in the morning allows the sun to burn off excess moisture on the surface throughout the day. This makes the lawn drier and less hospitable to fungi. The same applies with irrigation.
It is best that an underground irrigation system only activates when the soil is dry for 8 to 12 inches deep. Over watering the soil by means of irrigation makes the soil ideal for root fungi like spring dead spot and pythium root rot.
It is also important to avoid incorrectly fertilizing the grass for the breed and region. Too little fertilizer makes for unhealthy grass that can be overtaken by fungi, and too much fertilizer provides a breeding ground for fungi.
Other steps that can be taken to reduce fungus and increase lawn health include pruning back trees and bushes to allow the sun to reach the grass and regularly cutting the grass. In situations where proper lawn care does not help, mixing one part hydrogen peroxide with nine parts water and spraying it on the fungi is useful.