Your water management districts, Cooperative Extension Service, USDA Natural Resources Conservation Service or an irrigation professional can provide technical assistance. This is the most efficient time because temperature and wind speeds are at their lowest and evaporation is reduced. Also, grasses will be less susceptible to fungus if water is applied at the time dew normally forms. Don't apply more water until symptoms reappear. Experiment with gradual reductions in irrigation to see if plants can tolerate less water.
Some people use no irrigation, yet have healthy plants.