Set your sprinklers out early in the morning, and especially when the soil is dry.
Mold and fungus have a tendency to grow when the conditions are continually wet, so watering before the sun is at full strength will give the excess water time to evaporate during the day, and the dry soil will help water absorb deeper into the ground.
Additionally, adjust your watering system appropriately when the conditions change. Too much water or too little can greatly affect your lawn and may cause problems later on.
Reducing mold and fungus + deep moisture in the soil = a healthier lawn with less problems to deal with.