Turfgrass Quality Research Articles

Water conservation potential of smart irrigation controllers on St. Augustinegrass

A variety of technologies for reducing residential irrigation water use are available to homeowners. These “Smart Irrigation” technologies include evapotranspiration (ET)-based controllers and soil moisture sensor (SMS) controllers. The purpose of this research was to evaluate the effectiveness of these technologies, along with rain sensors, based on irrigation applied and turfgrass quality measurements on St. Augustinegrass ( Stenotaphrum secundatum (Walter) Kuntze). Testing was performed on two types of SMS controllers (LawnLogic LL1004 and Acclima Digital TDT RS500) at three soil moisture threshold settings. Mini-Clik rain sensors (RS) comprised six treatments at two rainfall thresholds (3 mm and 6 mm) and three different irrigation frequencies (1, 2, and 7 d/wk). Two ET controllers were also tested, the Toro Intelli-Sense controller and the Rain Bird ET Manager. A time-based treatment with 2 days of irrigation per week without any type of sensor (WOS) to bypass irrigation was established as a comparison. All irrigation controller programming represented settings that might be used in residential/commercial landscapes. Even though three of the four testing periods were relatively dry, all of the technologies tested managed to reduce water application compared to the WOS treatment, with most treatments also producing acceptable turf quality. Reductions in irrigation applied were as follows: 7–30% for RS-based treatments, 0–74% for SMS-based treatments, and 25–62% for ET-based treatments. The SMS treatments at low threshold settings resulted in high water savings, but reduced turf quality to unacceptable levels. The medium threshold setting (approximately field capacity) SMS-based treatment produced good turfgrass quality while reducing irrigation water use compared to WOS by 11–53%. ET controllers with comparable settings and good turf quality had −20% to 59% savings. Reducing the irrigation schedule (treatment DWRS) by 40% and using a rain sensor produced water savings between 36% and 53% similar to smart controllers. Proper installation and programming of each of the technologies was essential element to balancing water conservation and acceptable turf quality. Water savings with the SMS controllers could have been increased with a reduced time-based irrigation schedule. Efficiency settings of 100% (DWRS) and 95% (TORO) did not reduce turf quality below acceptable limits and resulted in substantial irrigation savings, indicating that efficiency values need not be low in well designed and maintained irrigation systems. For most conditions in Florida, the DWRS schedule (60% of schedule used for SMS treatments) can be used with either rain sensors or soil moisture sensors in bypass control mode as long as the irrigation system has good coverage and is in good repair.

Impacts of Altered Light Spectral Quality on Warm Season Turfgrass Growth under Greenhouse Conditions

Warm‐season turfgrass quality declines under shade due to reduced photosynthesis, increased disease pressure, reduced carbohydrate production, tree root competition, and reduced lateral stem growth. Another factor limiting turfgrass growth and development under tree shade is variable qualities of light filtered by trees. However, effects of various filtered wavelengths on turfgrass performance are lacking and deserve research. Therefore, a greenhouse project investigated the physiological and morphological responses of ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.], ‘Sea Isle 2000’ seashore paspalum (Paspalum vaginatum Swartz.), and ‘Tifway’ and ‘Celebration’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy] to variable light spectral qualities. Light treatments included a control without any shade cloths and four different color shade cloths filtering wavelengths 560 to 720 nm (blue shade cloth), 360 to 520 nm (yellow shade cloth), 360 to 560 nm (red shade cloth), and 360 to 720 nm (black shade cloth). The percent light reduction for each cloth was about 65% relative to the control. Data collected included visual turfgrass quality (TQ), relative clipping yield, relative chlorophyll concentration, relative shoot width, relative root biomass, relative root length density, relative specific root length, and root and shoot total nonstructural carbohydrates. Diamond was the least affected turfgrass by the color shade cloths, while Celebration and Sea Isle 2000 performed similarly. Tifway was the most sensitive turfgrass with the lowest TQ under color shade cloths. Yellow and red shades were least detrimental, while black shade most negatively inhibited parameters measured, followed by blue shade. This study implies different types of shade significantly impact the TQ of warm‐season turfgrasses.

The potential of a surfactant to restore turfgrass quality on a severely water-repellent golf green

Soil water repellency (SWR) is a common phenomenon on sand-based golf greens. Soils are considered severely water repellent if water droplets remain on the surface of undisturbed, air-dried soil samples for more than 600 seconds before penetrating. The objective of this research was to evaluate the potential of a surfactant to overcome SWR and restore turfgrass quality on a green with severe drought symptoms. The surfactant Aqueduct® was applied at a rate of 25 L ha−1 at weekly intervals from 4 June through 25 June 2008, either alone or after aeration with solid tines to 5 cm depth before each application. The experiment was irrigated uniformly corresponding to 1.65 times pan evaporation values from 4 June till 12 June, after which irrigation was not necessary due to natural rainfall. Conspicuous and statistically significant improvements in turfgrass quality occurred 10–12 days after the first application of surfactant, and the difference from untreated control plots continued to increase for about two and a half months after the completion of treatments. The improvement was accompanied by a significant increase in the SWC of the 0–20 cm soil layer and a deeper root system. The difference in WDPT between treated and untreated plots was significant at 1 cm, but not at 2, 3, 5 or 10 cm soil depths which were always far more water repellent than the thatch layer. Repeated aeration had no significant effect on turfgrass quality, and there was no significant interaction between surfactant and aeration treatments.

Dynamics of the soil nematode food web and nutrient pools under tall fescue lawns established on soil matrices resulting from common urban development activities

Human activity in urbanizing areas often disturbs the soil profile, but little is known of its effects on subsequent soil food web dynamics and biogeochemical cycling. We assessed dynamics of the soil nematode food web and nutrient pools in tall fescue lawns created on either disturbed topsoil or subsoil, with or without compost amendment, and managed under three nitrogen fertilizer rates for one year. Overall, total nematodes and number of nematode genera were higher in topsoil than subsoil plots throughout the study. Compost amendment temporarily reduced number of nematode genera and this effect lasted for six months. Total number of nematodes also initially declined in the compost-amended plots, but increased within two months and remained high thereafter. The nematode food web enrichment index was initially lower in subsoil compared with topsoil plots and steadily increased overtime, but structure remained low in subsoil throughout the study period. The food web structure declined even in topsoil under turfgrass over time. Compost amendment only increased food web enrichment temporarily, but had little effect on structure. Nitrogen fertilizer had no effect on either enrichment or structure of the food web. Temporal faunal profile analysis indicated that the soil food webs under turfgrass in all treatments converged over time, representing a highly enriched but poorly structured food web, and a strong bottom-up control on the soil food web. Soil macronutrients Ca, P, K, total N, total C, microbial biomass, and soil organic matter contents were higher in topsoil than subsoil, and were increased by compost amendment in both substrates. Soil P was only 18 μg/g in subsoil and it further declined by about 20% during the year. During the first two months after seeding, topsoil plots had lower turfgrass cover than subsoil plots (63 ± 5% and 95 ± 0%, respectively), but had higher weed cover (29 ± 5% and 2 ± 0%, respectively). After one year, turfgrass quality (greenness) was higher in topsoil than subsoil plots, in plots with compost amendment than those without, and in high N than low and no N plots. We conclude that anthropogenic activities, resulting in the loss of topsoil, can have a profound effect on the structure of the soil food web, which may severely limit its capacity to support optimal nutrient cycling, plant growth, and other essential functions.

Effect of the root-lesion nematode (Pratylenchus penetrans) on annual bluegrass (Poa annua)

This study was undertaken to assess the effect of various population densities of the root-lesion nematode (Pratylenchus penetrans) on the growth of annual bluegrass (Poa annua) under controlled conditions. In two separate experiments, the nematodes were inoculated at concentrations of 100, 500, 1000 or 5000 nematodes 100 cm‑3 soil per pot or per tube. Nine wk post-inoculation, root P. penetrans populations had increased linearly with initial nematode concentrations in both experiments. Growth and quality of turfgrass were uniform for all treatments, with no significant difference from the control. Under the current experimental conditions, P. annua was shown to be a tolerant host plant to P. penetrans.

Tools for Evaluating Native Grasses as Low Maintenance Turf

Visual ratings are the standard for evaluating turfgrass quality. However, to provide more objective evaluations and to address statistical concerns, other methods have been developed to measure turfgrass quality, including digital image analysis and measurements of chlorophyll content. These have been largely applied to traditionally used turfgrass species, but here we used these methods to evaluate turfgrass quality of nontraditional species and mixtures that are native or adapted to the intermountain west region of North America. Two fertilizer treatments (1.0 or 2.0 lb/1000 ft2 nitrogen) were applied to 21 different species and species mixtures in North Logan, UT. These plots were irrigated to replace 60% of the local evapotranspiration rate and were mowed at 4 inches. Turfgrass quality ratings were most effective in measuring quality among the diverse species used in this study. Because of the wider variation in acceptable visual characteristics and lower quality expectations for low-maintenance native turf, the objective evaluation methods proved less useful. Generally, chlorophyll meter data, digital image analysis of cover, and digital image analysis of color data were not well correlated with human visual quality ratings in this study. Measurements were well correlated in some species, but not in others. These methods can supplement, but cannot replace, human visual turfgrass quality ratings for comparison of dissimilar grasses.

Tools for Evaluating Native Grasses as Low Maintenance Turf

Visual ratings are the standard for evaluating turfgrass quality. However, to provide more objective evaluations and to address statistical concerns, other methods have been developed to measure turfgrass quality, including digital image analysis and measurements of chlorophyll content. These have been largely applied to traditionally used turfgrass species, but here we used these methods to evaluate turfgrass quality of nontraditional species and mixtures that are native or adapted to the intermountain west region of North America. Two fertilizer treatments (1.0 or 2.0 lb/1000 ft2 nitrogen) were applied to 21 different species and species mixtures in North Logan, UT. These plots were irrigated to replace 60% of the local evapotranspiration rate and were mowed at 4 inches. Turfgrass quality ratings were most effective in measuring quality among the diverse species used in this study. Because of the wider variation in acceptable visual characteristics and lower quality expectations for low-maintenance native turf, the objective evaluation methods proved less useful. Generally, chlorophyll meter data, digital image analysis of cover, and digital image analysis of color data were not well correlated with human visual quality ratings in this study. Measurements were well correlated in some species, but not in others. These methods can supplement, but cannot replace, human visual turfgrass quality ratings for comparison of dissimilar grasses.

Selecting Zoysiagrass Cultivars: Turfgrass Quality, Growth, Pest and Environmental Stress Tolerance

Applied Turfgrass ScienceVolume 6, Issue 1 p. 1-18 Turfgrass Management Guide Selecting Zoysiagrass Cultivars: Turfgrass Quality, Growth, Pest and Environmental Stress Tolerance Aaron J. Patton, Corresponding Author Aaron J. Patton Assistant Professor ajpatton@uark.edu University of Arkansas Cooperative Extension Service, Fayetteville, AR, 72701Corresponding author: Aaron J. Patton. ajpatton@uark.eduSearch for more papers by this author Aaron J. Patton, Corresponding Author Aaron J. Patton Assistant Professor ajpatton@uark.edu University of Arkansas Cooperative Extension Service, Fayetteville, AR, 72701Corresponding author: Aaron J. Patton. ajpatton@uark.eduSearch for more papers by this author First published: 19 October 2009 https://doi.org/10.1094/ATS-2009-1019-01-MGCitations: 5 Patton, A. J. 2009. Selecting zoysiagrass cultivars: Turfgrass quality, growth, pest and environmental stress tolerance. Online. Applied Turfgrass Science doi:https://doi.org/10.1094/ATS-2009-1019-01-MG. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume6, Issue12009Pages 1-18 RelatedInformation

Nitrogen and Plant Growth Regulator Influence on ‘Champion’ Bermudagrass Putting Green under Reduced Sunlight

Managing warm‐season turfgrasses with reduced sunlight is challenging due to C4 plant morphological limitations, such as reduced lateral stem growth. Adjusting cultural management practices, such as N and trinexapac‐ethyl (TE) [4‐(cyclopropyl‐a‐hydroxy‐methylene)‐3,5‐dioxocyclohexanecarboxylic acid ethyl ester], application may benefit turfgrass performance when sunlight is reduced. Therefore, a 2‐yr field study from 15 June to 15 September in 2006 and 2007 at Clemson University investigated the best management practices for sustaining a high quality ‘Champion’ bermudagrass (Cynodon dactylon (L.) Pers. X C. transvaalensis Burtt‐Davy) putting green maintained at a 3.2‐mm mowing height under reduced sunlight. Treatments included full‐sunlight, 55% full‐day shade, TE (0.02 kg a.i. ha−1 2 wk−1), Fe (2.7 kg ha−1 2 wk−1), and N as liquid urea at 147, 293, and 440 kg ha−1 yr−1. Data collection included visual turfgrass quality (TQ), total clipping yield, clipping chlorophyll concentration, root total nonstructural carbohydrates (TNC), thatch accumulation, and thatch depth. Overall, Fe applications minimally impacted parameters measured. Increasing N rates linearly increased TQ when grown under full sunlight. Applying N at ∼40% lower (147 kg ha−1 yr−1) than the typical recommended rates for ultradwarf bermudagrass putting greens improved Champion TQ under reduced light compared to higher N rates. Applying TE resulted in a linear TQ increase for full sunlight and shade‐grown Champion bermudagrass. Under reduced sunlight, a 15% chlorophyll concentration increase was noted for TE‐treated plots compared to nonTE‐treated plots. Shade reduced thatch accumulation 40% compared to sun‐grown Champion, which suggests less aggressive cultivation practices are required for thatch control under reduced light. Champion bermudagrass did not provide an acceptable putting green quality when grown under 55% full‐day shade, however, adjusting management practices enhanced Champion bermudagrass quality under reduced light.

Comparison of Turfgrass Visual Quality Ratings with Ratings Determined Using a Handheld Optical Sensor

Turfgrass performance can be assessed in terms of visual quality, but evaluators require training and may be distracted by many factors that affect accuracy and consistency. The objectives of this study were to assess a handheld optical sensor (GreenSeeker) for evaluating overall turfgrass quality in three turf species over two growing seasons, and to compare the combined time required for visual evaluation and data entry with the time required for the same functions using the handheld optical sensor. Visual quality ratings and sensor ratings were collected on schedules prescribed by the National Turfgrass Evaluation Program for the 2002 bermudagrass (Cynodon spp.), 2002 buffalograss (Buchloe dactyloides), and 2002 zoysiagrass (Zoysia spp.) studies in 2003 and 2004. Use of the sensor reduced the time required to complete data collection and data entry by 58% compared with human visual evaluation. Of the three species tested, the bermudagrass evaluation had the strongest correlation between ratings collected by the human evaluator and the sensor [r = 0.79 in 2003 (n = 343), r = 0.85 in 2004 (n = 343)]. The handheld optical sensor provided a consistent, objective evaluation of overall turfgrass quality and required less time than visual evaluation. The handheld optical sensor provides advantages for assessing turfgrass quality that cannot be realized by human evaluation, but the sensor alone is not sufficient for specific evaluations such as color, texture, or density that are routinely characterized by human evaluation.

Evaluation of Selected Fine-leaf Fescue Cultivars for Their Turfgrass Quality and Weed Suppressive Ability in Field Settings

A series of field studies were conducted from 1999 to 2005 in Ithaca, NY, at the Cornell Turfgrass Research Center as part of the National Turfgrass Evaluation Program (NTEP) to evaluate a collection of 78 fine-leaf fescue cultivars (Festuca spp.) for turfgrass quality, seedling vigor, and ability to inhibit the establishment of common annual and perennial weeds. Using these criteria, we evaluated the overall suitability of the cultivars for use in turfgrass settings, as well as their potential weed suppressive or allelopathic ability. The ability of fine-leaf fescue to displace weeds was visually evaluated by density-wise comparison, and several cultivars of the 78 studied consistently established well and provided good to very good suppression (greater than 70%) of common turf weeds when established at the same planting density. Other cultivars provided moderate (between 35% and 70%) to (< 30%) little weed suppression. Greater weed suppressivity is likely associated with the differential ability of fescue cultivars to establish rapidly and to form a dense canopy, as well as potential allelopathic interference. This study was conducted in conjunction with laboratory experiments that revealed that certain fine-leaf fescue cultivars produced phytotoxic root exudates that were released into the rhizosphere over time. Additional field studies conducted in Ithaca showed that cultivars Intrigue, Columbra, and Sandpiper were consistently more weed suppressive than the other fine-leaf fescues evaluated. Although our understanding of the dynamics of production and degradation of fine-leaf fescue root exudates in the rhizosphere is limited, recent field studies also suggest that allelopathic interference as well as the ability to rapidly establish influence subsequent weed infestation in fine-leaf fescue stands. From a more practical standpoint, certain fine-leaf fescue cultivars, including Intrigue, Columbra, Sandpiper, and Reliant II, could be recommended for use in low-maintenance turf settings in the northeastern United States due to their aesthetic appeal and their limited weed infestation in circumstances where herbicides are not applied.

Evaluation of Selected Fine-leaf Fescue Cultivars for Their Turfgrass Quality and Weed Suppressive Ability in Field Settings

A series of field studies were conducted from 1999 to 2005 in Ithaca, NY, at the Cornell Turfgrass Research Center as part of the National Turfgrass Evaluation Program (NTEP) to evaluate a collection of 78 fine-leaf fescue cultivars (Festuca spp.) for turfgrass quality, seedling vigor, and ability to inhibit the establishment of common annual and perennial weeds. Using these criteria, we evaluated the overall suitability of the cultivars for use in turfgrass settings, as well as their potential weed suppressive or allelopathic ability. The ability of fine-leaf fescue to displace weeds was visually evaluated by density-wise comparison, and several cultivars of the 78 studied consistently established well and provided good to very good suppression (greater than 70%) of common turf weeds when established at the same planting density. Other cultivars provided moderate (between 35% and 70%) to (< 30%) little weed suppression. Greater weed suppressivity is likely associated with the differential ability of fescue cultivars to establish rapidly and to form a dense canopy, as well as potential allelopathic interference. This study was conducted in conjunction with laboratory experiments that revealed that certain fine-leaf fescue cultivars produced phytotoxic root exudates that were released into the rhizosphere over time. Additional field studies conducted in Ithaca showed that cultivars Intrigue, Columbra, and Sandpiper were consistently more weed suppressive than the other fine-leaf fescues evaluated. Although our understanding of the dynamics of production and degradation of fine-leaf fescue root exudates in the rhizosphere is limited, recent field studies also suggest that allelopathic interference as well as the ability to rapidly establish influence subsequent weed infestation in fine-leaf fescue stands. From a more practical standpoint, certain fine-leaf fescue cultivars, including Intrigue, Columbra, Sandpiper, and Reliant II, could be recommended for use in low-maintenance turf settings in the northeastern United States due to their aesthetic appeal and their limited weed infestation in circumstances where herbicides are not applied.

Nitrogen Increases Evapotranspiration and Growth of a Warm‐Season Turfgrass

The effect of N fertilizer rate on Kikuyu turfgrass [Pennisetum clandestinum (Hochst. ex Chiov)] evapotranspiration was evaluated during two summers. Evapotranspiration was measured using weighing lysimeters (205 mm in diameter by 625 mm in length) inserted in turfgrass field plots (10 m2). The experiment was a randomized plot design with three replicates. Treatments included two turfgrass ages (established from 20 wk or 20‐yr‐old turfgrass) and three N application rates (0, 50, or 150 kg N ha−1 yr−1). Evapotranspiration ranged from 2.8 to 7.5 mm d−1 (or 56–81% of evaporative demand), and varied with daily evaporative demand, turfgrass age, and N fertilizer rate. The older turfgrass used more water than the younger turfgrass during both summers; while increasing the N application rate also increased evapotranspiration for both turfgrass types (younger turfgrass only in the second summer). Evapotranspiration was positively correlated with turfgrass growth (r2 = 0.74–0.80) and transpiring leaf area (r2 = 0.78). Older turfgrass at all N treatments, and the younger turfgrass receiving 150 kg N ha−1 yr−1, had adequate growth, color, and leaf N concentrations. Optimizing fertilizer applications such that the minimum N required to maintain turfgrass quality is applied, is an approach for decreasing water consumption by turfgrass.

Spatial Variability of the Illinois Soil Nitrogen Test: Implications for Sampling in a Turfgrass System

Nitrogen fertilization of turfgrass continues to be scrutinized due to environmental concerns. Practices that reduce fertilizer inputs without sacrificing turfgrass quality are needed, but a reliable test of N status in turfgrass is not currently available. The Illinois soil N test has been developed to predict crop response to applied N by measuring the amount of amino sugar N in the soil. Amino sugar N does not fluctuate as rapidly as other forms of N in soil. Our objective is to determine the spatial variation of amino sugar N in soil to determine sampling frequency requirements for use of the Illinois soil N test as a management tool on golf course fairways. Soil samples from 0 to 15, 15 to 30, and 30 to 45 cm were collected from golf course fairways in Minnesota and analyzed for amino sugar N concentration. Our data indicate that amino sugar N concentration decreases with depth but is not correlated to the concentration in the 0 to 15 cm layer. Amino sugar N concentrations measured on the four sampled fairways varied, but the spatial correlation present would allow for traditional soil sampling techniques to be used to assess the soil amino sugar N concentration within an area such as a golf course fairway.

Does N fertiliser regime influence N leaching and quality of different-aged turfgrass (Pennisetum clandestinum) stands?

The effects of N fertiliser regimes on N leaching and turfgrass quality during the establishment and maintenance of Kikuyu turfgrass (Pennisetum clandestinum (Holst. Ex Chiov)) were evaluated in a 24 month field study. Treatments included two turfgrass ages (established from 20 week or 20 year old turfgrass, the later included a 50 mm ‘mat’ layer), three N application rates (50, 100 or 150 kg N ha−1 yr−1) and three application frequencies (every 4 weeks, 4 applications per year, 2 applications per year); and included turfgrass plots that received no N fertiliser. Nitrogen leaching, measured using soil lysimeters, ranged from 35 to 69 kg N ha−1 by the end of 24 months, and varied with turfgrass age, but not N fertiliser regime. Greatest N losses occurred during turfgrass establishment, with up to 50% of all N leached in the organic form. We recommend measuring both total N and mineral N when assessing N leaching from turfgrass. The quality of the older turfgrass was maintained using less N fertiliser than the younger turfgrass, while increasing N application frequency improved the consistency of turfgrass growth and colour.

Winter Foot and Equipment Traffic Impacts on a ‘L93’ Creeping Bentgrass Putting Green

Creeping bentgrass (Agrostis stolonifera var. palustris Huds.) is desirable as a putting green turfgrass in the transition zone as a result of year-round green color, ball roll, and playability. However, management challenges exist for bentgrass greens, including winter temperature fluctuations. Frosts often cause cancellations or delays of tee time resulting in lost revenue. In response to this winter golf course management issue, a research project was initiated at Clemson University from 1 Dec. 2005 and 2006 to 1 Aug. 2006 and 2007 on a ‘L93’ creeping bentgrass putting green to determine the impacts of foot traffic or mower traffic and time of traffic application on bentgrass winter performance. Treatments consisted of no traffic (control), foot traffic, and walk-behind mower traffic (rolling) at 0700 and 0900 hr when canopy temperatures were at or below 0 °C. Foot traffic included ≈75 steps within each plot using size 10 SP-4 Saddle Nike golf shoes (soft-spiked sole) administered by a researcher weighing ≈75 kg. A Toro Greensmaster 800 walk-behind greens mower weighing 92 kg with a 45.7-cm roller was used for rolling traffic. Data collected included canopy and soil temperatures (7.6 cm depth), visual turfgrass quality (TQ), clipping yield (g·m−2), shoot chlorophyll concentration (mg·g−1), root total nonstructural carbohydrates (TNC) (mg·g−1), soil bulk density (g·cm−3), and water infiltration rates (cm·h−1). Time and type of traffic significantly influenced bentgrass winter performance. On all TQ rating dates, 0700 hr rolling traffic decreased TQ by ≈1.1 units compared with foot traffic at 0700 hr. In December, regardless of traffic application time, rolling traffic reduced bentgrass shoot growth ≈17%. However, in February, chlorophyll, soil bulk density, and water infiltration differences were not detected. By the end of March, all treatments had acceptable TQ. Root TNC was unaffected in May, whereas shoot chlorophyll concentrations were unaffected in May and August. This study indicates bentgrass damage resulting from winter traffic is limited to winter and early spring months and full recovery should be expected by summer.

Efficiency of Foliar Versus Granular Fertilization: A Field Study of Creeping Bentgrass Performance

ABSTRACT Limited information comparing foliar versus granular fertilization of turfgrasses is available. The objective of this research was to evaluate liquid and/or granular N fertilization on turfgrass quality, clipping yield, and root biomass of ‘L-93’ creeping bentgrass. Treatments consisted of two annual nitrogen (N) inputs, 127 and 190 kg ha−1, using 100% granular urea fertilizer, 50% granular urea + 50% liquid urea fertilizer, or 100% liquid urea fertilizer. These results suggest a rate of at least 190 kg N ha−1 yr−1 is needed to maintain acceptable bentgrass quality in the transition zone of the U.S. Combining both liquid and granular methods appear superior compared to relying on one method exclusively.

Phosphorus Requirements of St. Augustinegrass Grown in Sandy Soils

Phosphorus fertilization of St. Augustinegrass [Stenotaphrum secondatum (Walt.) Kuntze] is performed on the basis of soil tests designed for agronomic crops. The objectives of this study were to determine the critical minimum P application rate and soil and tissue P concentration of St. Augustinegrass grown in sandy soils. Three studies were conducted in a glasshouse using a Pomona sand, two Tavares sands, and a Pottsburg sand. Established pots of ‘Floratam’ St. Augustinegrass received P at 0, 0.14, 0.27, 0.54, and 1.09 g m−2 every four weeks for 16 weeks for Study 1 and 12 weeks for Studies 2 and 3. Critical minimum tissue P concentration was determined to be 1.8 g kg−1 on dry weight basis. Minimum P application rate was 0.14 g m−2 4‐wk−1 to obtain acceptable turfgrass quality and growth rate. Additional growth was not observed when Mehlich‐1 P level was greater than 7, 8, 9, and 5 mg kg−1 for Pomona sand, Tavares sand (a), Pottsburg sand, and Tavares sand (b), respectively. Phosphorus fertilization would not be recommended if soil Mehlich‐1 P concentration is above 10 mg kg−1 for sandy soils or tissue P level is beyond 1.8 g kg−1 on dry weight basis. Phosphorus application of 0.14 g m−2 4‐wk−1 is recommended when P is required.

Soil Temperature as an Application Indicator for Perennial Ryegrass Control

Research trials conducted at two locations in the spring of 2004 evaluated the effect of soil temperature as an indicator for application timings of certain sulfonylurea herbicides for perennial ryegrass control while maintaining acceptable turfgrass quality during bermudagrass spring transition. Herbicide application timings began when soil temperatures reached 17 C (April 14, 2004). Greater perennial ryegrass control 4 wk after initial treatment (WAIT) was achieved when sulfonylurea herbicides were applied at 26 C soil temperature compared to 17 or 21 C. Bermudagrass density 6 WAIT increased with treatments applied at 26 C soil temperature compared to cooler soil temperatures. There was a decrease in overall turfgrass quality 2 WAIT when treatments were applied at 17 C. However, by 4 WAIT all application timings provided overall turfgrass quality comparable to the untreated control. Acceptable turfgrass quality and maximum perennial ryegrass control was achieved by delaying transition-aid herbicide applications until soil temperatures reached 26 C and growing conditions were more conducive to bermudagrass growth.Nomenclature: Chlorsulfuron, flazasulfuron, foramsulfuron, metsulfuron, rimsulfuron, trifloxysulfuron-sodium, perennial ryegrass, Lolium perenne L. LOLPE, common bermudagrass, Cynodon dactylon (L.) Pers. CYNDA, bermudagrass, Cynodon dactylon Pers. × transvaalensis Burtt-Davy ‘Tifgreen’

Sensor-Based Automation of Irrigation on Bermudagrass during Dry Weather Conditions

Overirrigation of lawns with limited resources of potable water has increasingly become an issue for the state of Florida. A previous study showed that soil moisture sensors systems SMSs could lead to irrigation water savings during relatively wet/normal weather conditions. This research, as a follow-up comparison, was conducted under dry weather conditions. The first objective was to statistically evaluate the water savings potential of different commercially available SMSs during the first half of 2006. In the second half, the objectives were to quantify irrigation water use and to evaluate turfgrass quality differences among: 1 a time-based irrigation schedule system with and without a rain sensor; 2 time-based schedules compared to SMS-based systems; and 3 SMS-based systems under different irrigation frequencies. The experimental area was located in Gainesville, Fla. and consisted of common bermudagrass Cynodon dactylon L. Pers. plots. Four commercially available SMSs brands Acclima, Rain Bird, Irrometer, and Water Watcher were used to bypass scheduled irrigation cycles when the soil water content at the 7- to 10-cm depth was above field capacity. Time-based treatments with and without rain sensor feedback were set up as comparisons for irrigation depth applied, and a nonirrigated treatment for turf quality comparison purposes was implemented. Due to the dry weather conditions and/or infrequent rain events during the experi- ment, the nonirrigated plots as well as a broken SMS treatment resulted in turfgrass quality below the minimum acceptable level. The rest of the treatments had at least minimum acceptable turf quality. The treatment with rain sensor resulted in 13 to 24% less water applied than without the rain sensor treatment. Most SMS-based treatments resulted in significant irrigation water savings compared to the treatment without rain sensor, which ranged from 16 to 54% in the first half, and from 28 to 83% in the second half of 2006, for three of four SMS brands tested.