Kentucky Bluegrass Turf Research Articles

Ground ivy (Glechoma hederacea) control with boron and iron in Kentucky bluegrass turf

AbstractGround ivy (Glechoma hederacea L.) is a perennial broadleaf weed in the mint family (Lamiaceae) that is commonly found in turf in the temperate climates of the United States. Cultural practices that maintain dense turf are the best way to reduce weeds; however, cultural control methods alone cannot provide complete weed control. Herbicides are commonly used to control weeds in the turfgrass industry, but interest in alternative control methods is increasing. Applications of iron‐based products are an alternative chemical weed control option in turfgrass systems, but other micronutrients, such as boron, may also be a viable option. The objective of this study was to compare the efficacy of a chelated iron product as well as different boron‐based products for ground ivy control and also determine if these products injure Kentucky bluegrass (Poa pratensis L.). The products evaluated included borax, boric acid, Solubor (disodium octaborate tetrahydrate), and Fiesta (FeHEDTA) with a low and high rate tested for each. Ground ivy cover was reduced 77% or more from a single October application of all boron sources at the high rates and the high rate of Fiesta when evaluated 9 months later. The high rate of all boron‐containing products caused unacceptable turfgrass injury (<7) and reduced turf quality below acceptable levels (<6). No turfgrass injury or reduction in turf quality was observed in the Fiesta‐treated plots. These results indicate that applications of the micronutrient boron can be used to control ground ivy, but not without causing injury to Kentucky bluegrass.

Pythium Snow Blight of Kentucky Bluegrass Turf in a Golf Course in Hokkaido, Japan

Pythium Snow Blight of Kentucky Bluegrass Turf in a Golf Course in Hokkaido, Japan

Comparison of Shockwave aerification and conventional aerification methods on athletic fields

AbstractThe Shockwave (Imants) offers the potential to minimally disrupt the playing surface, relieve soil compaction, and potentially lower surface hardness. However, data are lacking on how the Shockwave compares to traditional aerification. The effects of hollow‐tine (HT), solid‐tine (ST), and Shockwave with a single pass (SW1) and perpendicular passes (SW2) were investigated and compared to an untreated control (C) for surface hardness, surface stability, soil moisture, water infiltration, percent green cover, and bulk density on established cultivar Rush Kentucky bluegrass (Poa pratensis L.) turf growing on native soil. Treatments were applied June–August with SW1 and SW2 receiving an additional treatment in September of each year. A modified Baldree traffic simulator was used to simulate 28 traffic events in the fall of each year. Data were analyzed using an exponential decay model, and the slope indicating cover loss event–1 was used to compare treatments. In both years of the study, the HT (–0.031 in 2017 and –0.085 in 2018) treatment had the least green cover loss per event. The SW2 (–0.051) had the greatest cover loss event–1 in 2017, while the C (–0.102) treatments experienced the largest cover loss event–1 in 2018. In 2017 after 20 simulated traffic events, surface hardness on SW2 treatments were 30% lower than the highest surface hardness. After simulated traffic in 2018, SW1 treatments resulted in 10% lower surface hardness compared to the hardest surface, indicating the Shockwave can reduce surface hardness. This research indicates that the Shockwave could replace ST in maintaining athletic fields.

Response of 110 Kentucky Bluegrass Varieties and Winter Annual Weeds to Methiozolin

Methiozolin is a new isoxazoline herbicide that has scarcely been tested in Kentucky bluegrass turf. A field trial was conducted in Blacksburg, VA, to determine response of 110 Kentucky bluegrass varieties and winter annual weeds to sequential fall applications of methiozolin. At 1.5 and 6 mo after initial treatment (MAIT), Kentucky bluegrass injury I30values (predicted methiozolin rate that causes 30% Kentucky bluegrass injury) ranged between 3.4 to more than 10 times the recommended methiozolin rate for annual bluegrass control. Methiozolin at all rates reduced cover of annual bluegrass, common chickweed, corn speedwell, hairy bittercress, mouseear chickweed, and Persian speedwell but increased cover of parsley-piert. For all varieties, methiozolin at 2 kg ai ha−1increased Kentucky bluegrass cover, turf quality, and turf normalized difference vegetation index (NDVI) relative to the nontreated check at 6 MAIT. Kentucky bluegrass relative cover change (RCC) was attributed primarily to weed control but was inversely correlated with methiozolin rates because of increased weed control and reduced Kentucky bluegrass growth. Despite the decline in RCC with increasing methiozolin rates, most Kentucky bluegrass varieties treated with the highest methiozolin rate (6 kg ha−1) still had greater Kentucky bluegrass cover than the nontreated check at 6 MAIT. Results from this study indicate that two fall applications of methiozolin at rates beyond that previously reported for annual bluegrass control can safely be applied to a broad range of Kentucky bluegrass varieties spanning most of the known genetic classifications.

Fifteen Years of Nitrogen Leaching from a Kentucky Bluegrass Turf

Most research on nitrate‐nitrogen (NO3–N) leaching in turfgrass was conducted on recently established sites and indicates that leaching poses little risk to the environment. The potential for greater NO3–N leaching from mature turf sites is relatively unknown. Nitrogen (N) leaching from a Kentucky bluegrass (Poa pratensis L.) turf was measured for 15 yr using monolith lysimeters. From 1998 through 2002, half of the lysimeters were treated annually with urea at a high rate of 245 kg N ha−1 (49 kg N ha−1 application−1) and half of the lysimeters were treated at a low rate of 98 kg N ha−1 (24.5 kg N ha−1 application−1). Flow‐weighted mean NO3–N concentrations in leachate for the low N rate were below 5 mg L−1 for every year but one of the 15 yr of research. For the high N rate, NO3–N concentrations in leachate for many dates from 2000 through 2002 were higher than the drinking water quality maximum contaminant level of 10 mg L−1. Due to high concentrations of NO3–N in leachate, the high N rate was reduced from 245 to 196 kg ha−1yr−1 in 2003. From 2004 through 2013, there was a decline in NO3–N leaching. For both N rates, the flow‐weighted mean NO3–N concentration in 2013 was less than in 1998, when the research was initiated. This research indicates that, as a turfgrass system ages, there is a critical annual N rate, above which NO3–N concentration in leachate may exceed the maximum contaminant level, and below which there is minimal risk.

A Greenhouse-based Inoculation Protocol for Fungi Causing Crown Rust and Stem Rust Diseases of Kentucky Bluegrass Turf

Rusts are destructive fungal diseases that can cause severe thinning and unattractive discoloration of kentucky bluegrass (KBG; Poa pratensis L.). Currently, turfgrass breeding programs rely on field evaluations to screen KBG germplasm for rust resistance; methods that are expensive, labor intensive, and require large turf areas. The availability of a greenhouse-based assay to perform prescreening of KBG germplasm for resistance to rust diseases before field trials would allow breeders to remove the poorest performing plants before field evaluations thus enhancing breeding efficiency. In this study, we set out to develop a reliable, low-cost greenhouse inoculation protocol for the two most common rust pathogens of KBG in temperate growing regions: Puccinia coronata and Puccinia graminis, the causal agents of crown and stem rust, respectively. Using a modified inoculation assay and custom-built plexi-glass chambers adapted from protocols used for cereal rust pathogens, urediniospores of crown and stem rust fungi developed on inoculated plants 10 to 14 days postinoculation. Real-time polymerase chain reaction (PCR) assays, disease symptomology, and morphology of urediniospores confirmed the presence and identity of both rust pathogens from inoculated host tissue. The inoculation protocols described here represent an effective method to accelerate screening of KBG germplasm for resistance to crown and stem rust diseases. Infection of KBG plants in the greenhouse will also allow breeders to maintain populations of crown and stem rust fungi throughout the year, providing a reliable and ongoing source of pathogen inoculum for experimentation and screening in the future.

Matching Subjective Assessments of Sod Strength to Quantitative Measurements of Peak Shear Force with Predominately Kentucky Bluegrass Sod

Adequate turfgrass sod strength for harvesting and handling is typically determined by the producer’s past experience and subjective appraisal. This study was conducted to determine the relationship between producer subjective sod-strength assessments and quantitative shear-strength measurements with predominantly kentucky bluegrass (Poa pratensis L.) turf. Across three consecutive growing seasons, 93 samples were collected from sod fields in Rhode Island and assessed for sod strength by subjective and quantitative methods. Producer subjective ratings of sod strength were significantly (P < 0.0001) associated with quantitative measurements of peak force required to shear a sod strip. Minimally acceptable strength occurred most frequently when peak shear force was between 55 and 85 kg·m−1 width of sod; whereas preferred sod strength occurred most frequently when peak shear force was between 70 and 140 kg·m−1 width of sod. Once peak force exceeded 58 and 86 kg·m−1, there was a > 50% probability that sod strength would be judged at least adequate and at preferred strength, respectively, up to a peak force of 140 kg·m−1. The results suggest that quantitative measurements of shear strength can be related to producer subjective assessments, and provide unbiased benchmark values to guide management decisions for kentucky bluegrass sod production.

Development and application of a TaqMan real-time PCR assay for rapid detection of Magnaporthe poae

In North America, one of the most important root diseases of Poa and Festuca turf is summer patch, caused by Magnaporthe poae. Detection and identification of M. poae in infected roots by conventional culture-based methods is difficult and time consuming, typically taking 3 wk or longer to accomplish. In this study, a culture-independent, TaqMan real-time PCR assay was developed for the detection of M. poae from the roots of fungicidetreated and non-treated Kentucky bluegrass (Poa pratensis) turf. The assay was validated with the target pathogen, closely related fungal species and a number of other microorganisms that inhabit the same host and soil environment. This assay was more sensitive (could detect as little as 3.88 pg genomic DNA of M. poae), rapid and accurate compared to direct microscopic observation and isolation on a selective medium. The real-time PCR detection results corresponded closely to visual assessments of disease severity in the field. Utilization of this assay in diagnostic laboratories will enable turfgrass managers to more quickly and effectively detect and potentially reduce fungicide usage through early and accurate identification of the pathogen.

Effects of Surface Conditions on Baseball Playing Surface Pace

Abstract The speed at which a baseball travels after impact with a playing surface has been referred to as playing surface pace. Little information is available regarding the effects of varying construction and maintenance practices on the pace of baseball playing surfaces. Research was conducted to evaluate the effects of construction and maintenance practices on a non-turfed basepath, Kentucky bluegrass (Poa pratensis L.) turf, and six synthetic turf surfaces. Factors evaluated on the non-turfed basepath included soil compaction at installation, surface scarification, and topdressing with a soil conditioner (calcined clay). The effects of cutting height and thatch thickness were evaluated on Kentucky bluegrass, while the effects of simulated traffic and grooming were evaluated on synthetic turf. On the non-turfed basepath, increasing soil compaction yielded increases in surface pace. Calcined clay topdressing and increasing scarification depth did not affect surface pace. On Kentucky bluegrass, varying cutting height and thatch thickness levels had no effect on surface pace. On synthetic turf, increases in simulated traffic resulted in slight increases in pace. Surface pace measurements on synthetic turf were less variable than those made on natural turfgrass. The results indicate that the pace of commonly used baseball playing surfaces is not easily altered with minimally invasive maintenance procedures and should be addressed at construction or during aggressive renovations.

Nitrate Leaching from Kentucky Bluegrass Soil Columns Predicted with Anion Exchange Membranes

Ideal nitrogen (N) management for turfgrass supplies sufficient N for high‐quality turf without increasing N leaching losses. A greenhouse study was conducted during two 27‐wk periods to determine if in situ anion exchange membranes (AEMs) could predict nitrate (NO3–N) leaching from a Kentucky bluegrass (Poa pratensis L.) turf grown on intact soil columns. Treatments consisted of 16 rates of N fertilization, from 0 to 98 kg N ha−1 mo−1 Percolate water was collected weekly and analyzed for NO3–N. Mean flow‐weighted NO3–N concentration and cumulative mass in percolate were exponentially related (pseudo‐R2 = 0.995 and 0.994, respectively) to AEM desorbed soil NO3–N, with a percolate concentration below 10 mg NO3–N L−1 corresponding to an AEM soil NO3–N value of 2.9 μg cm−2 d−1 Apparent N recovery by turf ranged from 28 to 40% of applied N, with a maximum corresponding to 4.7 μg cm−2 d−1 AEM soil NO3–N. Turf color, growth, and chlorophyll index increased with increasing AEM soil NO3–N, but these increases occurred at the expense of increases in NO3–N leaching losses. These results suggest that AEMs might serve as a tool for predicting NO3–N leaching losses from turf.

Single Fall Applications of Coated Urea Fertilizers Produce a High Quality Kentucky Bluegrass Turf

Single Fall Applications of Coated Urea Fertilizers Produce a High Quality Kentucky Bluegrass Turf

Effect of leaf nitrogen concentration versus CND nutritional balance on shoot density and foliage colour of an established Kentucky bluegrass (Poa pratensis L.) turf

A 3-yr field study was conducted in a loam and a sand site to determine the effects of N, P, and K application rates on N status, shoot density and foliage colour of Kentucky bluegrass clippings and to derive critical N values. The experiment was arranged in a completely randomized block design with four replicates and three nutrients, N (0 or 50 to 300 kg ha-1 yr-1), P (0 or 21.8 to 87.3 kg P ha-1 yr-1), and K (0 or 41.7 to 250 kg K ha-1 yr-1), equally broadcast six times per growing season. We examined N concentration values, log-transformed N concentration values, and CND values for compositional nutrient simplexes comprising one (VN1), three (VN3), five (VN5), or 11 (VN11) macro- and micro-nutrients. Critical values for N expressions were obtained from linear relationships with targeted visual shoot density and foliage colour ratings that were closely related to each other (R2 = 0.92). The highest coefficients of determination (0.975 to 0.980) were obtained with VN5 and VN11. The VN5 values were consistent with literature data and across experimental sites, and were the most successful (99% success) in diagnosing N sufficiency in 328 qualified specimens from commercial sod farms. Compared with raw concentrations, the CND transformation reduced from 0.6 to 0.1 the degree of inter-correlation among nutrients in principal component analysis and was amenable to a χ2 distribution of CND indices. Using a critical imbalance index (CNDr2) of 5.6as χ2 value, and a critical CND IN2 index of 1.5 for a 5-nutrient simplex, we diagnosed as imbalanced 179 qualified specimens of which 110 specimens presented excessively high N level among the 328 qualified specimens in commercial stands. The proposed five-nutrient CND norms proved to be effective in diagnosing N status in Kentucky bluegrass clippings across experimental, literature, and survey data sets. Key words: Plant tissue nutrient diagnosis, DRIS, CND, Kentucky bluegrass nitrogen fertilization, turfgrass shoot density, turfgrass foliage colour

The Fate of Nitrogen Applied to a Mature Kentucky Bluegrass Turf

Research on nitrate‐nitrogen (NO3–N) leaching in turfgrass indicates that, in most cases, leaching poses little risk to the environment. Most of the research was conducted on sites that were recently established, and the potential for greater NO3–N leaching from mature turf sites is unknown. The fate of nitrogen (N) was examined for a 10‐yr‐old Kentucky bluegrass (Poa pratensis L.) turf using intact monolith lysimeters and microplots. From October 2000 through July 2002, half of the lysimeters and microplots were treated annually with urea at a high rate of 245 kg N ha−1 (49 kg N ha−1 application−1). The remaining lysimeters and microplots were treated annually with urea at a low rate of 98 kg N ha−1 (24.5 kg N ha−1 application−1). The Oct. 2000 urea application was made with 15N double‐labeled urea to facilitate fertilizer identification among clippings, verdure, thatch, soil, roots, and leachate. The average total recovery of applied labeled fertilizer nitrogen (LFN) for the low and high N rates was 78 and 74%, respectively. NO3–N concentrations in leachate for the low N rate were typically below 5 mg L−1. For the high N rate, NO3–N concentrations in leachate were often greater than 20 mg L−1. Over approximately 2 yr, 1 and 11% of LFN was recovered in leachate for the low and high N rates, respectively. This research indicates that single dose, high rate, water soluble N applications (49 kg N ha−1 application−1) to mature turfgrass stands should be avoided to minimize the potential for NO3–N leaching.

Impact of mowing and weed control on broadleaf weed population dynamics in turf

Various turf management activities may influence weed population dynamics and interfere with weed control. The effects of a biocontrol agent, Sclerotinia minor, a chemical herbicide, Killex™, and mowing height on broadleaf weed dynamics were examined in two turfgrass stands for two consecutive years. Mowing did not reduce the population densities of dandelion or the ground cover of broadleaf weeds. In the second year, mowing significantly reduced white clover density, but significantly increased broadleaf plantain density, particularly at the closest mowing height (3–5 cm). Apart from the close height, the S. minor and Killex™ treatments were equally effective in suppression of dandelion, white clover, broadleaf plantain, and prostrate knotweed in the second year. Common mallow increased in the herbicide treated plots and other species including yellow woodsorrel, yellow toadflax and lambsquarters increased in abundance in plots mowed at the 3–5 cm height and in plots treated with Killex™. Significant differences between the Killex™ and S. minor treatments on dandelion population dynamics were rarely present and did not favour either treatment. S. minor did not damage the turfgrass, but Killex™ reduced turf quality in 25% of the plots. The application of S. minor with a regular, medium height (∼7 cm) mowing regime was highly effective in controlling broadleaf weeds in temperate Kentucky bluegrass turf.

Breeding CWG‐R Crested Wheatgrass for Reduced‐Maintenance Turf

Using reduced‐maintenance turfgrass as an alternative to current high‐maintenance turfgrass species would conserve resources, reduce labor, and potentially reduce pollutants in the environment. CWG‐R is an experimental population of crested wheatgrass [Agropyron cristatum (L.) Gaertn.] from Iran that has shown potential as a low‐maintenance turf. The objective of this research was to estimate the genetic variation for turf traits within the CWG‐R population when evaluated under a reduced‐maintenance regimen. Ninety CWG‐R clonal lines were established in 1998 near Logan, UT, as spaced‐plant plots in a RCB design with four replicates. Maintenance of 50% ET0 replacement, 97.74 kg of nitrogen ha−1 yr−1, and mowing at 7.62 cm was approximately 40% lower than typical for high‐input Kentucky bluegrass (Poa pratensis L.) turf. Critical turf traits, including spring regrowth, season‐long (March–October) and mid‐summer (June–July) turf quality, color, and rhizomatous spread were evaluated in 1999 and 2000. Significant genetic variation among clonal lines was evident with broad‐sense heritabilities of 0.65, 0.76, 0.45, and 0.76 for spring regrowth, season‐long turf quality, color, and rhizomatous spread, respectively. Several clonal lines remained green throughout the summer months and maintained acceptable turf quality and color ratings during the critical mid‐summer period. The high broad‐sense heritability estimates within this population indicate potential for successful improvement of critical turf traits by phenotypic selection. These results indicate that that CWG‐R could be an important low‐maintenance turf‐type crested wheatgrass germplasm.

Quantitative and qualitative responses of an established Kentucky bluegrass (Poa pratensis L.) turf to N, P, and K additions

Kentucky bluegrass is a common turf species used on golf courses, sports fields, municipal parks, sod farms, road banks, as well as residential and school yards. Our objective was to determine the effects of N, P, K rates on turfgrass quantitative response (clipping yield and underground turf biomass) and qualitative response (shoot density and foliage colour) under a continuous clipping removal. A 3-yr field study was conducted on two sites, a sand that met the specifications of the United States Golf Association (USGA) and a loam. The factorial experiment was arranged in a randomized complete block design with four replicates and different levels of three nutrients, N (0 or 50 to 300 kg ha-1 yr-1), P (0 or 21.8 to 87.3 kg P ha-1 yr-1), and K (0 or 41.7 to 250 kg K ha-1 yr-1). The maximum clipping yield was produced at the rate of 200 kg N ha-1 yr-1 in the loam and 300 kg N ha-1 yr-1 in the sand. Increasing N rates linearly reduced underground turf biomass. Added P and K had no effect on clipping yield and underground turf biomass. Nitrogen significantly improved shoot density and foliage colour. However, equivalent shoot density and colour ratings required 40 to 80 kg more N ha-1 yr-1 in the sand compared to the loam. Phosphorus and K had no significant effect on shoot density and colour in the loam. Colour response to P and K depended on N rates in the sand. Fertilizer units needed to increase soil test P averaged 6 kg added P ha-1 mg-1 PM-III kg-1 across soil types. To replenish soil K, 7 kg K ha-1 per mg KM-III kg-1 were required in the sand, and 3 kg K ha-1 per mg KM-III kg-1 in the loam. Phosphorus and K fertilizer programmes should account for P and K removals to maintain low to medium fertility levels for P, and medium for K when conditions are similar to those in this research. Key words: Turfgrass clipping yield, underground turf biomass, turfgrass shoot density, turfgrass foliage colour, Kentucky bluegrass fertilization

Mass Balance of15N Applied to Kentucky Bluegrass Including Direct Measurement of Denitrification

Although the fate of fertilizer applied to turfgrass has been studied in the past, recovery of applied fertilizer N is typically low, and denitrification has been cited as the reason. The objectives of this research were twofold: (i) to examine the fate of 15 N applied to Kentucky bluegrass (Poa pratensis L.) turf as KNO 3, including direct measurement of denitrification; and (ii) to determine whether and how plants affect fertilizer-N recovery. Polyvinyl chloride (PVC) cylinders, modified to permit atmospheric sampling, were used throughout field experiments during the spring and summer 1999 and a greenhouse experiment in 2000. Potassium nitrate (98.5 atom % 15 N) was applied in solution at 49 kg N ha -1 to replicated plots, and atmospheric samples were collected three times a day from 0800 to 1100, 1100 to 1400, and 1400 to 1700 h during a 6-wk period in the spring and a 4-wk period during the summer of 1999. Emission of N 2 or N 2 O ranged from 3.3 to 21.3% and from 0.3 to 5.9% of labeled fertilizer N (LFN), respectively. Recovery of LFN in the soil or plant, plus that emitted as N 2 or N 2 O, ranged from 57.4 to 73.2%. A 4-wk greenhouse experiment comparing LFN recovery for bare soil and turf, including gas emission and leachate, was initiated in the summer of 2000. Total emission of LFN as N 2 or N 2 O was 19.0% for the turfgrass, as compared with 7.3% for the bare soil. Corresponding values for total recovery of LFN were 70.6 and 84.2%, respectively.

A Geographic Information System for identification of potential alternative crops utilizing soil and climatic variables in the Bighorn Basin, Wyoming

AbstractThe Bighorn Basin is an important agricultural region in Wyoming. To promote expansion of economic prospects within the Bighorn Basin, we explored the feasibility of introducing alternative crops into the area. Currently, the major crops in this region are sugar beet, barley, alfalfas, and dry beans. Diversification of agricultural cropping systems within the Bighorn Basin is an important step in enhancing the state's economy. This research provides preliminary results for evaluating diversification by determining crops that may potentially be cultivated in the Bighorn Basin region. Four of the 28 alternative crops investigated in this project include amaranth, buckwheat, canola, and faba bean. A Geographic Information System (GIS) was used to combine spatial data identifying areas with unique combinations of characteristics (e.g., soils, frost-free period, temperature, etc.) for introduction of new crops. The GIS was used to compile data layers for different soil and climatic variables. A soils data layer was developed for the study area using a predictive model based on the region's surficial geology, bedrock geology, and elevation. Monthly minimum, mean, and maximum summer temperatures, precipitation, growing degree-days and frost-free season were obtainedfrom weatherstations located in the Bighorn Basin, where 30-year averages have been collected by the National Climate Data Center. Using geostatistics, information obtainedfrom weather stations was utilized to develop continuous data layers for 31 climatic conditions related to the study area. A compilation of growth parameters for 28 alternative crops included various soil and climatic conditions that were used to identify areas with potential to support these new crops. Maps of alternative crop production areas suggested that 8 crops (amaranth, chickpea, onion, quinoa, saffiower, sesame, sorghum, and sunflower) could potentially be cultivated in eastern Bighorn Basin where temperatures are warmer, another 12 crops (broccoli, buckwheat, canola, carrot, cauliflower, crambe, Kentucky bluegrass turf seed, leek, lentil, lettuce, mint, and radish) could be produced in western Bighorn Basin where temperatures are cooler, and 8 additional crops (asparagus, beet, cabbage, cowpea, faba bean, field pea, medic seed, and tall fescue turf seed) may possibly be cultivated throughout the Bighorn Basin study area in suitable soils. The alternative crop production area maps derived from this projectwillbe useful to potential growers, land-use planners, and county and state agencies in the Bighorn Basin seeking information on different agricultural practices and new production systems.

Kentucky Bluegrass Responses to Mowing Practice and Nitrogen Fertility Management

ABSTRACT The practice of leaving clippings on the lawn recycles nutrients and reduces yard-waste but the residue of unsightly clippings deters widespread adoption. An experiment was conducted on a Kentucky bluegrass (Poa pratensis L.) turf to evaluate mowing practice in combination with various fertilizer types and application rates. The main objective was to minimize clipping yield while achieving acceptable turfgrass quality. The return of clippings, as compared to clipping removal, was associated with fewer weeds and a darker green more luxuriant turf. Furthermore, the benefits of clipping return were achieved using half (97.6 kg ha□ 1 yr□ 1) as much N as is typically applied (195.2 kg ha□ 1 yr□ 1) for high maintenance turf. Slow-release N fertilizers were shown to reduce spring clipping yield and thereby make the practice of clipping return a more acceptable mowing practice.

Movement of herbicides under two irrigation regimes applied to turfgrass

Our objective was to investigate the movement of the dimethylamine salt of (2,4-dichlorophenoxy) acetic acid (2,4-D), dicamba, and 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP), when applied to Kentucky bluegrass turf under both infrequent and frequent irrigation regimes. The turfgrass was established on 50-cm length and 20-cm diameter undisturbed soil columns of Nicollet (fine-loamy, mixed, mesic-Aquic Hapludolls) with intact macropores. The infrequent irrigation regime consisted of four 2.54-cm applications, and the frequent regime consisted of 16 0.64-cm applications. On average, the amounts of 2,4-D, dicamba, and MCPP recovered from the soil columns, and in the leachate, under the infrequent irrigation regime were 3.0, 22.4, and 1.1%, respectively. The average amounts of 2,4-D, dicamba, and MCPP recovered from soil columns, and in the leachate, under the frequent irrigation regime were 3.2, 6.3, and 2.3%, respectively. Average values of 1.9, 21.8, and 0.7% of the applied 2,4-D, dicamba, and MCPP, respectively, were measured in the leachate from the soil columns under infrequent irrigation, in contrast to 0.1, 3.4, and 0.2%, respectively, from the soil columns under frequent irrigation. We concluded that the frequency of irrigation can have an impact on the movement of these herbicides through soil profiles.