Site‐specific management units (SSMUs), similar in soil, plant, and irrigation requirements, are foundational to efficient management in precision agriculture. This concept is applied to management of complex turfgrass sites to improve irrigation practices. An experimental mobile unit mapped two golf fairways' turfgrass (Paspalum vaginatum SW.; ‘Salam’) in Naples, FL in summer 2006 on a 2.5 m grid for volumetric water content (VWC) by time‐domain reflectrometry at field capacity and normalized difference vegetative index (NDVI). Objectives were to determine suitability of the GPS‐enabled mapping device and to develop protocols for defining and characterizing SSMUs by geographic information system (GIS) methods. Semivariogram analysis revealed that the mapping grid of 2.5 m was within the lowest observed range of 11.7 m for geospatial dependence for either VWC or NDVI. SSMU delineation was based on stable landscape traits of VWC at field capacity and topographic factors; with NDVI data as secondary. Descriptive and geostatistical means to best characterize SSMUs are presented. Use of field capacity VWC based distribution uniformity (DU) parameters is discussed for efficient irrigation scheduling applications within SSMUs.

Annual bluegrass [Poa annua ssp. reptans (Hauskins) Timm.] often comprises a large portion of golf course greens, yet its shallow root system and extensive seedhead production limit its turf quality. The purpose of this investigation was to determine if annual bluegrass seedheads could be suppressed and rooting enhanced by the plant growth regulator mefluidide [N ‐(2,4‐dimethyl‐5‐{[(trifluoromethyl) sulfonyl]amino} phenyl)acetamide] and the wetting agent Aqua‐Gro (polyoxyethylene esters and ether of cyclic acid and alkylated phenols, silicone anti‐foam emulsion). Chemicals were applied prior to seedhead emergence during 1983 and 1984 to annual bluegrass grown in a rhizotron in fine quartz sand. Root elongation of mefluidide‐treated annual bluegrass was superior to the control for 2 to 4 weeks following Spring 1983 application. Maximum rooting depth of mefluidide‐treated turf was significantly greater than that of Aqua‐Gro‐treated or untreated turf during May 1983. Aqua‐Gro applied at either 4.2 or 8.4 L ha−1 generally did not affect rooting. In 1983, mefluidide (0.07 or 0.14 kg ha−1) prevented seedhead emergence throughout the entire seedhead production period (approximately 8 weeks) when applied under environmental conditions favoring uptake. Leaf tip yellowing occurred for 3 to 4 weeks following mefluidide application. Mefluidide‐treated turf, however, exhibited quality superior to untreated turf for approximately 6 weeks following discoloration. Aqua‐Gro provided little seedhead suppression and reduced quality for about 10 days following application. In 1984, environmental conditions were not conducive to chemical uptake so 1983 results were not corroborated. Mefluidide appears promising as an annual bluegrass management tool; however, more information is needed to determine the influence of environmental conditions on mefluidide uptake and its ability to suppress seedheads and enhance rooting at low rates.

Construction of creeping bentgrass (Agrostis palustris Huds.) golf greens with topsoil mixtures that contain 90% or more sand has led to the appearance of irregularly shaped areas of wilted or dead turfgrass known as localized dry spots (LDS). Objectives were to determine by means of a survey the association between management practices and the severity of LDS, and to compare the chemical and physical properties of LDS and adjacent healthy areas (HA) of greens. Turf managers from ten golf courses and the University of Georgia Turfgrass Plots completed a 34-question survey pertaining to management practices used on their respective greens. Four of the golf courses and the University Turf Plots were selected as sampling sites for soil from both LDS and HA. Soil was analyzed for moisture content, and particle size, as well as hydrophobicity via the water droplet penetration time, and contact angle methods. Soil organic matter, soluble salts, pH, P, K, Ca, Mg, Zn, Mn, B, and NO,, were also determined. In addition, soil from each area was viewed with a scanning electron microscope. Dry spots occurred at all locations surveyed and no correlation was observed between management practices and the severity of LDS. No differences in soil chemical properties were found between LDS and HA, but water droplet penetration time and contact angle were greater in LDS compared to HA. This hydrophobic condition was confined to the top 50 mm of soil in the dry spot samples and coincided with the presence of an organic coating on sand grains that was observed by scanning electron microscopy.