These stripes result from mowing when the plant is entering the early stages of drought stress. The wheels,mower housing, blade, and/or feet apparently destroy the integrity of the leaves and thus even when the area is watered, the leaves will not green-up. The plant will regrow from the crown given four weeks or more with regular irrigation or rainfall and the stripes should disappear. To prevent these stripes in the first place, avoid mowing turf that is under drought stress (bluish-gray color),