Keep the mower blades sharp. A dull mower shreds the grass blades. This not only causes the lawn to be temporarily unsightly, but it may also provide wounds for infectious fungi to invade. Never allow the grass to get higher than four to five inches between mowings. In most circumstances, leaving clippings on the lawn is a good practice.
Clippings provide mineral nutrients to the soil as they decompose.
Leaving clippings on the lawn generally has little impact on lawn diseases. About the only time when clipping removal may help suppress a disease in lawns is during an active outbreak of Brown Patch on tall fescue turf. See the Extension publication ID-112, Brown Patch Disease in Kentucky Lawns, for more information on this disease. Watering Provide adequate moisture during periods of drought. Avoid frequent, light waterings.