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Understanding root growth response of creeping bentgrass {Agrostis stolonifera L.) to coring will help golf course superintendents maintain high quality putting green turf. The objective of this field study was to examine the effects of coring on summer rooting in young creeping bentgrass grown on a sand-based root zone and maintained as a putting green. The study was initiated on 7-mo-old 'Providence' creeping bentgrass in 2006 and compared spring (SP) only coring, spring plus three summer (SU) corings (SP + SU) and a noncored control through 2007. The minirhizotron imagining technique was used to measure total root count (TRC) and total root length (TRL) from late spring to late summer. The percentage of the TRC in the surface 0- to 6-cm root zone depth averaged over measurement dates was 48 to 53% and 33 to 44% among all treatments in 2006 and 2007, respectively. Greater TRC were observed in 2006 with 28, 51, and 50% lower TRC's found in SP + SU, SP only, and noncored plots in 2007, respectively. Spring + SU coring generally reduced TRC and TRL at various root zone depths and dates during the first year of establishment. In 2007, greater TRC and TRL were observed throughout the 0- to 24-cm root zone in SP + SU cored compared to SP only and noncored plots. Thus, SP + SU coring in the second study year promoted creeping bentgrass root growth and/or longevity, but coring during the first summer of establishment reduced rooting. [ABSTRACT FROM AUTHOR]

Frequent vs. infrequent irrigation are two common irrigation practices. This field study was conducted on 'Providence' creeping bentgrass (Agrostis stolonifera L.) grown on a sand-based rootzone and maintained as a putting green. The objectives of this study were to measure several creeping bentgrass performance and physiological factors as influenced by light and frequent (LF) vs. deep and infrequent (DI) irrigation. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, while DI plots were irrigated at leaf wilt to wet soil to a depth of ≥24 cm. The LF-irrigated creeping bentgrass exhibited very good color and quality throughout most of 2006 and 2007, whereas DI-irrigated bentgrass exhibited acceptable quality in 2007 but not in 2006. The DI-irrigated bentgrass had lower chlorophyll levels in leaf and sheath tissue in 2006, but developed better color and quality and had higher chlorophyll levels in late summer of 2007 vs. LF-irrigated bentgrass. Creeping bentgrass subjected to DI irrigation developed a less thick thatch-mat layer that contained less organic matter than that found in LF-irrigated plots. Twice the amount of water was applied to the LF- vs. the DI-irrigated plots. [ABSTRACT FROM AUTHOR]

Light and frequent (LF) and deep and infrequent (DI) irrigation are two common practices for golf course managers. Few studies have compared the effects of these two opposing irrigation practices on summer root performance in creeping bentgrass (Agrostis stolonifera L.). The objectives of this field study were to quantify summer root development and longevity in response to LF vs. DI irrigation in 'Providence' creeping bentgrass grown on a sand-based rootzone. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, whereas DI plots were irrigated at leaf wilt to wet soil to a depth ≥24 cm. Root measurements were obtained using the minirhizotron imaging technique and included total root count, total root length (TRL), total root surface area (TRSA), and average root diameter. When averaged over the entire 0- to 24-cm rootzone depth, DI-irrigated creeping bentgrass produced a greater number of roots, longer root lengths, and a larger root surface area than LF-irrigated turf. Average root diameters were smaller in DI-irrigated creeping bentgrass in the summer of 2007. Compared with data collected in 2006, the 2-yr-old turf had 55 and 32% fewer roots in LF- and DI-irrigated bentgrass by September 2007, respectively. There were similar reductions in TRL and TRSA between years in both irrigation regimes. Deep and infrequent irrigation stimulated root growth throughout the 0- to 24-cm rootzone in May and June and promoted root longevity in summer. [ABSTRACT FROM AUTHOR]

Coring is a common cultural practice used on golf courses. The reported effects of coring alone on thatch-mat accumulation have been mixed. The objectives of this field study were to examine the effects of spring and summer coring on thatch- mat thickness and organic matter accumulation in creeping bentgrass (Agrostis stolonifera L.). Turfgrass color and quality and chlorophyll content were also monitored. The study site was 'Providence' creeping bentgrass grown on a sand-based rootzone maintained as a putting green. Three coring regimes were assessed as follows: spring-only coring (1.27-cm-diam. tines), spring plus three summer corings (0.64-cm-diam. tines), and a noncored control. At the end of the second year, spring-only and spring-plus-summer cored plots had developed a 66 and 89%, respectively, thicker thatch-mat layer compared with noncored bentgrass. The total organic matter content (weight loss-on-ignition) in thatch- mat layers, however, generally was similar among all three regimes in both years. This indicated that the organic matter was diluted by inclusion of sand from topdressing or reincorporation of cores. Thus, organic matter concentration (i.e., gravimetric organic: dry weight of the cores) in the thatch-mat layer was much lower in plots of both coring regimes vs. noncored plots. Both spring-only and especially spring-plus-summer coring caused substantial reductions in turf quality for a 2-wk period. Spring-plus-summer coring resulted in increased chlorophyll levels as well as improved turf color and quality in late summer. [ABSTRACT FROM AUTHOR]

Annual bluegrass (Poa annua L.; ABG) can be a major weed problem in golf course turf. Research-based information on the seasonal emergence patterns of ABG is limited. The objectives of this four-year field study were (i) to determine seasonal ABG emergence patterns in Maryland, (ii) to determine peak period(s) of ABG emergence, and (iii) to determine the date and estimated percentage of seedlings emerged when the rate of emergence declines. Annual bluegrass seedlings were found to emerge between August and May in two Maryland golf course roughs. A majority (50-70%) of seedling emergence occurred between late September and mid-October, and peak germination generally was observed in early October. The linear increase in ABG seedling emergence generally ended by early November; however, 24% of all seedlings emerged between November and May. No major ABG emergence cycles were observed during the spring in any year. Mean daily temperatures generally were ≤20°C during peak ABG emergence periods, and germination was stimulated by precipitation. Since the genetic diversity of ABG is well known, these findings may only be applicable to Maryland and regions with similar environmental conditions. [ABSTRACT FROM AUTHOR]

Creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw.] and perennial ryegrass (Lolium perenne L.) are commonly grown fairway grasses that are susceptible to dollar spot (Sclerotinia homoeocarpa F. T. Bennett; DS) and gray leaf spot [Pyricularia grisea (Cooke) Sacc; GLS.] diseases, respectively. This field study assessed the influence of two irrigation regimes (light and frequent nighttime versus deep and infrequent morning irrigation) and six chemical treatments including: chlorothalonil (tetrachlornisophthalonitrile), paclobutrazol [(2RS,3RS)-1-(4.chlornphenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)pentan-3-ol; PB], wetting agent (polymeric polyoxyalkylene 95% oxoalkonyl hydroxyl polyoxlalkane diyl 5%; WA), chlorothalonil + PB, chlorothalonil + WA and chlorothalonil + PB + WA on DS and GLS severity over a 3-yr period. Dollar spot was more severe in late summer in creeping bentgrass that received deep and infrequent versus light and frequent irrigation in 2002 and 2004 and disease severity was negatively correlated with volumetric soil moisture (r = -0.77 to -0.96). Soil moisture levels above 0.25 cm³ cm-3 were associated with an improved ability of chlorothalonil, PB, and WA to suppress DS, but they had no effect on GLS. In 2002, GLS rapidly and severely damaged even fungicide-treated plots, and there was no irrigation effect. In 2004, gray leaf spot was more severe in light and frequent nighttime irrigated blocks versus deep and infrequent morning irrigated blocks. Chlorothalonil (8.0 kg a.i. ha-1) provided effective GLS control when applied on an 8-d interval in 2004 but only in infrequently irrigated blocks where disease pressure was less. [ABSTRACT FROM AUTHOR]

Examines the usability of bio-organic nitrogen on suppressing turfgrass diseases. Effect of nitrogen on thatch and soil organic matter level; Correlation between dollar spot and soil microbial activity; Comparison on the effectivity between synthetic and non-synthetic sources of nitrogen.

Analyzes the influence of irrigation, fungicide and fertilizer on brown patch severity in perennial ryegrass. Shortage of information on the cultural management practices; Importance of the slow nitrogen release characteristics of sulfur-coated urea in disease reduction; Effect of the extended fungicide application interval.

Analyzes the influence of mowing height on brown patch severity in perennial ryegrass. Effect of nitrogen source; Effect of iprodione; Absence of relationship between brown patch severity and soil pH or crown tissue carbohydrates.