A. Control thatch. Thatch is an accumulation of living plant parts that intermingle with plant debris in various stages of decomposition to form a layer on the soil surface. Thatch is not always detrimental to turf. A thin layer of thatch may help insulate plant structures in soil from extremes of heat and cold. It may even serve as a mulch to prevent loss of soil moisture by evaporation. However, lawns in the Lee’s Summit area should not exceed 3/4 inches in their thatch layer. Too much thatch harbors disease pathogens and also holds moisture that can increase disease out-break. Remove moderate thatch by aerating on an annual basis. Aeration removes a small section of thatch and distributes soil on top of the thatch layer to break down the thatch from the top sides as well as the bottom side.
B. Water properly. The more often grass is wet and the longer it remains wet, the greater are the chances of disease problems occurring. During dry periods, enough water should be applied at one time to provide moisture for a week. This means to a soil depth of 6 to 8 inches. It may help to water at short intervals on clay soils or where the thatch layer is thick to ensure penetration instead of run-off. Don’t let your lawn get so dry it becomes stressed, which could make the grass susceptible to disease. Ideally, irrigation should be applied between midnight and early morning when the turfgrass is normally wet. This avoids extending the duration of leaf wetness.
C. Mow frequently and high. Mow so no more than 1/3 of the grass blade is removed. Any more than that can put the grass under stress. Turfgrass plants mowed shorter than their optimal height of cut are, in general, are more susceptible to disease. Optimal cutting heights for cool-season grasses range from 2.5 to 4 inches.
D. Increase air movement to allow drying of grass. This can be done by removal or thinning of trees and shrubs. Pruning also allows sunlight to penetrate.
E. Don’t have one pure stand of grass species. Disease can spread rapidly unchecked by a single cultivar. Use a blend of several species to insure having at least one or more disease-resistant varieties. Each year new disease-resistant grasses are coming to the market.
F. Do not over fertilize in the spring. A lush, thick lawn can be an opportunity for disease.
G. Keep mower blades sharp so they don’t leave excessive tears in the leaves making the grass leaves susceptible to disease entry. Mowing creates wounds through which fungi can enter the plant and infect it. A dull blade inflicts more and bigger wounds that not only increase the potential for infection by turfgrass pathogens and also increases the potential for moisture stress.
H. Keep mowers clean so they don’t spread disease.
I. Maintain good drainage. Turf areas that stay constantly wet because of poor drainage are prime targets for decline. Surface contouring and subsurface drainage are costly, but permanent solutions. Core aeration and slicing are turf management practices that can be repeated during the year to temporarily increase infiltration rate and promotes soil drying.