SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/60100
FieldScience other hand is often maintained at heights as low as 0.5 inches on athletic fields. Increased mowing frequencies have also been shown to improve turfgrass health and vigor. For instance, simply increasing mow- ing frequency from once to twice per week has been shown to improve cover, surface strength and wear tolerance, all import fac- tors when trying to provide a high quality playing surface that is resistant to weed en- croachment. FERTILIZATION When developing a fertilization plan for athletic fields, consider the environ- mental conditions in which your turfgrass thrives. Fertilize Kentucky bluegrass at in- creased rates (1.0-1.5 lbs N/1,000 ft2 decreased rates (0.5-1.0 lbs N/1,000 ft2 /month) throughout the summer, total- ing 3-5 lbs N/1,000 ft2 /year. Bermuda- grass, because it is a warm season turf, will require relatively high application rates (1.0-1.5 lbs N/1,000 ft2 /month) during the summer and relatively light applica- tion rates (0.5-1.0 lbs N/1,000 ft2 in the spring and fall, totaling 5-6 lbs N/1,000 ft2 /year. Weeds that indicate nutrient deficiencies include white clover and common dande- lion. Dollar spot and rust thrive in nitrogen deficient turfgrass, therefore, a light applica- tion of a quick release fertilizer high in ni- trogen, such as urea (46-0-0) or ammonium nitrate (34-0-0), is often prescribed. How- ever, brown patch and Pythium blight thrive when high nitrogen levels are combined with poor drainage, humidity and heat stress. A fertilizer application during these circumstances would only increase disease severity. It is advantageous to select complete fer- tilizers containing relatively high concentra- tions of nitrogen (N), low concentrations of phosphors (P) and moderate levels of potas- sium (K), a ratio of approximately 4N-1P- 2K. Apply controlled release fertilizers in the summer months when microbial activ- ity and the potential for fertilizer burn is high and apply quick release fertilizers high in nitrogen (applied at a maximum of 0.5 lbs N/1,000 ft2 /application) in the spring and/or fall when rapid turfgrass recovery is required between sporting events. 10 SportsTurf | April 2012 /month) Table 1: Herbicides and their intended strategy of use for management of an- nual broadleaf and grassy weeds in cool season and warm season turfgrass, table developed by Aaron Hathaway. Cool season turf Annual broadleaves Annual grasses carfentrazone (burndown), isoxaben (preemergence) quinclorac for crab- grass, fenoxyprop for goosegrass (postemergence) Annual bluegrass ethofumesate, bispyribac sodium, mesotrione (postemergence) quinclorac (postemergence); numerous products (preemergence) pronamide, (preemergence); trifloxysulfuron- sodium, foramsulfuron (postemergence) paclobutrazol, flurprimidol (plant growth regulators) Caution: apply only when warm season turfs are growing vigorously; do not apply 6-8 weeks prior to or during field use as it will halt growth Apply postemergence early in growth stage if possible Be prepared for turfgrass and annual bluegrass injury Warm season turf carfentrazone (burndown) Strategy Control before they produce and disseminate seed IRRIGATION Environmental conditions and turfgrass /month) in the spring and autumn, and species are often intertwined factors when making irrigation adjustments throughout the seasons. Cool season turfgrass will likely require more frequent irrigation during pe- riods of drought stress when root necrosis occurs (Image 2). It is important to note that diseases like Pythium blight and brown patch thrive in poorly drained, over-irri- gated soils, while dollar spot thrives on turf- grass with prolonged periods of leaf wetness. Moss and algae are often signs of over-irrigation and applications should be reduced when present. Annual bluegrass is often a result of over-irrigation, particularly when coupled with over-fertilization. On the other hand, because warm season grasses, like bermudagrass, tolerate relatively high atmospheric temperatures and produce extremely deep rooting, less frequent irriga- tion can be tolerated. Deep and infrequent irrigation will promote deeper rooting, par- ticularly when the surface is allowed to dry between irrigation. Allowing the surface to dry between irrigation events will decrease the potential of disease associated with over- irrigation and prolonged period of leaf wet- ness, but also increases the potential for development of drought stress. Therefore, managers using the deep and infrequent ir- rigation regime should regularly monitor for drought stress and localized dry spot. CULTIVATION Turfgrass root growth can be maximized and soil organic matter can be minimized with soil cultivation. Soil compaction causes reduced root growth, poor drainage and, ul- timately, increases susceptibility to disease and weed encroachment. Weeds associated with compacted soils include knotweed and goosegrass. Excessive organic matter accumulation can cause decreased drainage and rooting, and increased disease activity. The vast ma- jority of infectious turfgrass pathogens can survive on organic matter when the turf- grass is healthy, which increases the poten- tial for infection during periods of adverse environmental conditions. Cultivation prac- tices that reduce organic matter accumula- www.sportsturfonline.com