Patches of dead or dormant grass in the otherwise healthy lawn indicate that something other than the weather is preventing it from growing. In rare circumstances, a sprinkler head may be damaged, preventing the area from being adequately watered. It might also be infested with pests that are wreaking havoc on the soil and vegetation, necessitating treatment. Finally, it might be the consequence of overfertilizing a specific region or overuse of weed killer, both of which can harm the grass.