Cultural management of turf diseases

Though it can be challenging to maintain intensively-managed turfgrass without fungicides, good cultural practices will reduce the need for fungicide applications and make necessary applications more effective. In fact, effective and well-timed cultural practices may minimize or eliminate the need for fungicide applications in lawns and other less intensely maintained turfgrass areas.

Starting right 


Prepare the site well. Remove stumps, construction materials and other debris. Improve drainage where necessary, and fill in low areas. Test soil pH and adjust to 6.0 to 7.0 if required. Break up soil clumps to provide a uniform area for seed or sod.

Choose seed or sod carefully (see Turfgrass Selection: Species and Cultivars). Inspect sod for diseases or other problems. Choose high quality, pathogen-free seed. Many disease resistant cultivars are now available and should be included in blends and mixtures. Genetic variability in turfgrasses will reduce the chance for epidemics that kill or damage large areas of turf.

General landscaping decisions can have significant impacts on turf health. Pruning of tree branches may increase light penetration to allow better turfgrass growth. Trees, shrubs, and other plantings should be placed to allow good air circulation, so turf will dry quickly after rain or dew. In very shady areas, shade-tolerant turfgrass cultivars or other groundcovers should be planted.

Seed should be planted only in well prepared soil with good drainage when temperatures stay in the range to allow rapid germination and establishment. Keep soil and seed moist, but do not over-water.

Routine Care

Fertilizers - Apply according to current recommendations and based on a soil test. Excess nitrogen will cause succulent growth that is more susceptible to disease. Avoid nitrogen applications (especially water soluble/quick-release fertilizers) during leaf spot season early in spring, during hot, humid weather, and just before dormancy in fall, which may leave turf more susceptible to snow molds and winter injury. Be sure, however, to meet the minimum nitrogen requirement for the turfgrass species and use as some diseases (e.g. red thread, rusts, and dollar spot) are encouraged when nitrogen is deficient.

Herbicides - Herbicides can stress turfgrasses and make them more susceptible to diseases. Apply carefully according to label directions and with attention to environmental conditions.

Some herbicides may have fungistatic effect and provide some degree of disease control. Noting fungistatic occurrences may be useful for reducing the amount of fungicide applied, by applying fungicides in combination with fungistatic herbicides.

Liming - Adjust pH according to soil test recommendations. Disease occurrence may increase at pH extremes (too high or too low). Lime applied late in autumn can increase Microdochium patch (pink snow mold) incidence and high pH can predipose turf to take-all patch infection during the spring. 



Mowing - Mowing wounds turfgrasses and can spread pathogens (disease-causing organisms). Minimize wounding and shredding of grass blades by keeping mower blades sharp and adjusted properly. If possible, mow when the turf is dry. Mow as high as possible for species and the turf use, using the maximum mowing height in hot weather. Avoid mowing more than one-third of the total height at each cutting to reduce stress to the root system. Mowing in autumn until turf stops growing can help to reduce damage from snow molds.

Watering - Water is necessary for good plant growth, but too much water floods open spaces in the soil, depriving roots of oxygen. Disease-causing fungi reproduce by spores that, like seeds, need water to germinate and infect turf. Dry turfgrass blades reduce disease by reducing infection. Deep and infrequent watering is strongly preferred to shallow, frequent watering to minimize leaf wetness and to encourage an extensive root system. Every effort should be made to not extend the duration of time blades are wet from dew or irrigation. Do not water in late afternoon or early evening. Night irrigation after dew appears may help conserve water, but is not recommended on hot, humid nights because it can increase some diseases (Figure 2). Avoid light, frequent sprinklings (syringing) except to prevent wilting in close-cut or shallow rooted turf and during hot, dry weather. In certain situations, keeping upper soil layers moist may help to reduce the occurrence of necrotic ring spot and summer patch.

Figure 2. When NOT to water turf

Thatch - Thatch is mostly composed of partially decayed above- and below-ground lateral stem tissue (stolons and rhizomes). A thin layer is beneficial in most turf situations. When thatch is more than 1/2” thick, it reduces nutrient and water absorption and harbors insect pests and disease pathogens. Prevent excessive thatch formation by providing adequate fertility in combination with aeration, verticutting and topdressing when needed. Mechanical removal of thatch is disruptive and should be accomplished in spring and late summer when time and conditions will allow for sufficient turf recovery.

Compaction - Several diseases (e.g. necrotic ring spot, summer patch, or athracnose basal rot) are worse in areas with compacted soil. Core aeration can help relieve soil compaction and improve turf quality. On some sites, traffic management may also be appropriate to minimize soil compaction.

Targeted cultural practices

Some sites have a history of disease problems, while others exist in a growing environment conducive to certain diseases.  For some pathogens, targeted cultural practices can go a long way towards preventing disease occurrence, reducing severity of disease when it does occur, and promoting recovery from damage. Table 18 details cultural management strategies for some of the most common turf diseases encountered in the Northeast.

Table 18. Cultural management strategies for common turf diseases.