Over the past couple of decades, there has been an increased interest in evaluating the environmental impacts of some turfgrass management practices. Two independent studies were conducted to examine different questions of turfgrass management impacts and sustainability. The first study examined the inputs and outputs of four different turfgrass home lawn systems. Two of these systems were designated as high maintenance and were composed of either a pure stand of Kentucky bluegrass (Poa pratensis L.) or tall fescue (Festuca arundinacea Schreb.). The other two systems were designated as low maintenance and were composed of either a pure stand of zoyisagrass (Zoysia japonica Steud.) or a mixed species endemic polystand. Soil samples were taken yearly from each plot and analyzed to determine total carbon content. Results from this study indicated carbon and nitrogen pools were not significantly different between the four systems but depth of sampling was significant. For the second study, various formulated surfactants were examined to determine if they could enhance the fungicidal activity of a protein washed and concentrated from tobacco leaves (Nicotiana tabacum L.) that has been shown to be effective in combating foliar-infecting turfgrass diseases in previous studies. Since previous studies indicated the protein was most effective at high concentrations when applied every seven days, it was hypothesized a surfactant may allow the protein to perform as well for a longer period of time or at lower concentrations. The efficacy of the protein against a root infecting pathogen (Ophiosphaerella korrae) was also examined. Results from this study indicated a water based surfactant may allow solutions of the protein applied every 14 days to perform similarly to solutions of the protein alone applied every 7 days without a surfactant against Sclerotinia homoeocarpa F. T. Bennett. Also, the protein did appear to be somewhat effective in combating the root infecting pathogen tested in this study when applied on a schedule similar to current commercial fungicide recommendations.

Das Ziel der vorliegenden Arbeit war es, die Eignung von vierzehn Pflanzenarten des Wirtschaftsgrünlands für die Etablierung von Grasnarben für die Hühnerfreilandhaltung zu untersuchen. Neun Gräser und fünf Kräuter, deren hohe Leistungsfähigkeit aus intensiv bewirtschafteten Systemen, und deren gute Schnitt-, Weide- und Trittverträglichkeit bekannt sind, wurden vergleichend bewertet. In einem Feldexperiment wurde die Verträglichkeit der Pflanzen gegenüber Beweidung mit Hühnern untersucht. Die Hypothese lautete, dass sich die Leistungsfähigkeit der Arten deutlich unterscheiden würde, da die Störung, die durch Beweidung mit Hühnern erzeugt wird, stärker und von anderer Natur ist als in anderen Bewirtschaftungssystemen. Monokulturen und eine Mischsaat der vierzehn Arten wurden einer Umtriebsbeweidung mit Legehennen in drei Stufen der Weidedauer unterzogen. Die Wirkung der Faktoren Pflanzenart, Weidedauer und Umtrieb auf Bodendeckung, Dichte der Triebe und Vegetationspunkte, und Wachstum der oberirdischen Biomasse wurde analysiert. Aus ersteren Zielgrößen wurde die Resistenz der Grasnarbe gegenüber der Beweidung abgeleitet, aus der dritten ihre Resilienz. Die Hypothese, dass sich die untersuchten Arten stark im Hinblick auf ihre Resistenz und Resilienz gegenüber Beweidung mit Hühnern unterscheiden würden, wurde bestätigt. Unsere Ergebnisse deuteten darauf hin, dass Gräser prinzipiell besser für die Bepflanzung von Auslaufflächen geeignet sind als Kräuter. Die Arten Festuca arundinacea und Poa supina zeigten mit einer Bodendeckung von über 80 %, einer konstanten Triebdichte und einer gleich bleibenden, vergleichsweise hohen Wachstumsrate von mehr als 4,8 g Trockenmasse m-2 d-1 die beste Leistungsfähigkeit bei wiederholter Beweidung und langer Weidedauer. In einem ergänzenden Gefäßversuch im Gewächshaus wurde untersucht, welche mit der Wuchsform in Zusammenhang stehenden Eigenschaften die Toleranz der Pflanzen gegenüber Beweidung mit Hühnern erklären. Die Hypothese bestand darin, dass die Biomasseallokation vor der Störung und die Lage von Speicherorganen und Knospen für klonales Wachstum die Schädigungstoleranz bestimmen würden; sie würde bei Arten hoch sein, bei denen diese Organe konzentriert an der Sprossbasis und unterhalb von oder nahe der Erdoberfläche liegen. Eine Auswahl der im Freilandversuch verwendeten Pflanzenarten, die drei Wuchsformen repräsentierte (Arten ohne Ausläufer; Arten mit Stolonen; Arten mit Rhizomen) wurde einer standardisierten mechanischen Schädigung in drei Intensitäten ausgesetzt, welche zugleich auf Spross und Wurzel wirkte. Die Ergebnisse dieses Versuchs zeigten, dass die Pflanzenart, nicht aber die Wuchsform die Toleranz gegenüber Schädigung bestimmten. Die höchste Toleranz wurde bei F. arundinacea und Poa pratensis festgestellt. Der Wiederaufwuchs oberirdischer Biomasse war über alle Arten und Intensitäten der Behandlung hinweg stark mit der relativen Wurzelbiomasse (der Wurzelbiomasse der behandelten Pflanze im Verhältnis zu der der Kontrollpflanze) korreliert, allerdings nicht mit der Wurzelbiomasse vor der Behandlung. Die Resistenz der Wurzel gegenüber mechanischer Schädigung ist daher offenbar eine wesentliche Determinante der Toleranz gegenüber der untersuchten Störung. Schließlich wurde der Einfluss von botanischer Zusammensetzung und Degradierung der Grasnarbe auf das Nahrungssuchverhalten der Hühner untersucht. In dem oben erläuterten Feldexperiment war die Häufigkeit der Verhaltensweisen Picken an Pflanzen, Picken am Boden und Scharren aufgezeichnet worden. Aus den Daten ging hervor, dass Pflanzenart und Degradierung der Grasnarbe das Nahrungssuchverhalten der Hühner signifikant beeinflussten. Eine steigende Weidedauer reduzierte die Bodendeckung grüner Vegetation signifikant; allerdings unterschieden sich die untersuchten Pflanzenarten deutlich im Hinblick auf das Ausmaß der Degradierung, die durch standardisierte Beweidungsdauer erzeugt wurde. Bei steigender Weidedauer und sinkender Bodendeckung grüner Vegetation war bei den meisten Pflanzenarten eine Abnahme der Häufigkeit des auf die Grasnarbe gerichteten Pickverhaltens (Picken an Boden und Pflanzenteilen summiert) nachweisbar. Dieses Ergebnis wird als bedeutsam für das Tierwohl erachtet, da in Umwelten, die wenig Anreiz zu Picken an Objekten bieten, die Gefahr besteht, dass die Tiere vermehrt Federpicken zeigen. Wir leiten aus diesen Ergebnissen ab, dass die Wahl von Pflanzenarten wie P. supina, die sowohl eine hohe Resistenz gegenüber der durch Beweidung verursachten Störung aufweisen, als auch einen starken Anreiz zu Nahrungssuchverhalten, und insbesondere zu Picken liefern, als Begrünung den Beitrag der Auslauffläche zu Tierwohl und –gesundheit fördern können. Zusammenfassend haben unsere Experimente gezeigt, dass die Wahl der Pflanzenart zur Auslaufbegrünung ein wichtiger Faktor zur Gewährleistung der Multifunktionalität der Grasnarbe ist. Pflanzen, die bei langer Beweidung eine stabile Bodendeckung und starkes Wachstum aufweisen, können einen höheren Anteil der im Auslauf anfallenden Nährstoffmengen binden und tragen somit zum Schutz von Boden und Wasser bei. Eine Grasnarbe, die zusätzlich das Nahrungssuchverhalten anregt, begünstigt Tierwohl und -gesundheit. Von den untersuchten Arten zeigte P. supina insgesamt das beste Ergebnis in Bezug auf diese Kriterien; F. arundinacea zeichnete sich zwar durch eine hohe Resistenz gegenüber der Störung durch die Beweidung aus, allerdings schien diese Art weniger stark bepickt zu werden. Wir schließen daraus, dass die Wahl der Pflanzenart für die Auslaufbegrünung als eine wichtige Methode des Auslaufmanagements betrachtet werden kann, die etablierte Methoden der Auslaufpflege, wie Umtriebsbeweidung mit ausreichenden Beweidungspausen und eine Gestaltung des Auslaufs, welche die Tiere zur Nutzung der gesamten Fläche animiert, ergänzen sollte.

Large and small crabgrass are problem turfgrass weeds. Due to increasing cosmetic pesticide bans, assessment of crabgrass recruitment timing and cultural management response is important. This project determined that natural populations emerged later than cool season turfgrass typically establishes. While turf vigour may affect the survival of crabgrass through competition, it does not directly impact crabgrass recruitment. Considering fertilization, chamber experiments confirmed that KNO3 increased fresh seed germination. This effect did not occur with aged seed suggesting that KNO3 affects seed dormancy and not germination per se. Experiments with a model turfgrass system showed similar results where fresh seed recruitment increased with increasing fertilizer rate. Fertilization had no significant effect on recruitment in field trials. Although fresh seed was spread in the fall, recruitment did not occur until spring when seed is considered non-dormant. This suggests that typical home owner fertilization will not have a direct impact on crabgrass recruitment.

abstract: As a result of growing populations and uncertain resource availability, urban areas are facing pressure from federal and state agencies, as well as residents, to promote conservation programs that provide services for people and mitigate environmental harm. Current strategies in US cities aim to reduce the impact of municipal and household resource use, including programs to promote water conservation. One common conservation program incentivizes the replacement of water-intensive turfgrass lawns with landscapes that use less water consisting of interspersed drought-tolerant shrubs and trees with rock or mulch groundcover (e.g. xeriscapes, rain gardens, water-wise landscapes). A handful of previous studies in experimental landscapes have shown that converting a turfgrass yard to a shrub-dominated landscape has the potential to increase rates of nitrate (NO3-) leaching. However, no studies have examined the drivers or patterns across diverse management practices. In this research, I compared soil nutrient retention and cycling in turfgrass and lawn-alternative xeriscaped yards along a chronosequence of time since land cover change in Tempe, Arizona, in the semi-arid US Southwest. Soil inorganic extractable nitrogen (N) pools were greater in xeriscapes compared to turfgrass lawns. On average xeriscapes contained 2.5±0.4 g NO3--N/m2 in the first 45 cm of soil, compared to 0.6±0.7 g NO3--N/m2 in lawns. Soil NO3--N pools in xeriscaped yards also varied significantly with time: pools were largest 9-13 years after cover change and declined to levels comparable to turfgrass at 18-21 years. Variation in soil extractable NO3--N with landscape age was strongly influenced by management practices that control soil water availability, including shrub cover, the presence of sub-surface plastic sheeting, and the frequency of irrigation. This research is the first to explore the ecological outcomes and temporal dynamics of an increasingly common, ‘sustainable’ land use practice that is universally promoted in US cities. Our findings show that transitioning from turfgrass to water-efficient residential landscaping can lead to an accumulation of NO3--N that may be lost from the soil rooting zone over time, through leaching following irrigation or rainfall. These results have implications for best management practices to optimize the benefits of water-conserving residential yards. / Dissertation/Thesis / Masters Thesis Biology 2015

Population growth in regions of the Intermountain West has resulted in rapid growth of residential neighborhoods. In Utah, the landscapes associated with these expanding neighborhoods consume vast quantities of treated water. This is a concern in all states of the Intermountain West, as water becomes increasingly scarce. Traditionally used turfgrasses, trees and other plants in Intermountain West landscapes require significant amounts of supplemental water considering the intense sunlight, dry winds and sparse rainfall typical of the region. Characterizing the interactions between turfgrass and tree species in these landscapes can aid in the identification of candidate species that consume less nutritional and water resources, while maintaining satisfactory appearance. A study was conducted investigating the nature of interactions between tree and turfgrass species in a constructed landscape of the Intermountain West. An experiment was performed investigating differences in rooting length and volume between combinations of two tree (Robinia pseudoacacia L., Gleditsia triacanthos var. inermis L.) and three turfgrass [Poa pratensis L., Buchlöe dactyloides (Nutt.) Engelm., Festuca arundinacea Schreb.] species. A minirhizotron system was used to obtain root images at three times during the growing seasons of 2006 and 2007 at depths from 1-15 cm in each tree-turfgrass rooting zone. Images were analyzed to determine combined total volume, length, and surface area of turfgrass and tree roots. This research shows that root growth differences occur in turfgrass-tree combinations containing all three turfgrass species. Buffalograss best resisted possible root growth inhibition, regardless of tree combination. Further evidence shows that Robinia secondary growth is vulnerable to presence of turfgrass in proximity.

No description available.

Perennial ryegrass (Lolium perenne L.) is a cool-season turfgrass susceptible to low temperature injury. Wilt-based (WB) irrigation is a common practice in scheduling turf irrigation as an alternative to well-watered (WW). Moisture stress has been shown to promote cold hardiness but this has not been investigated in response to WB irrigation. Measurements of 13C isotope discrimination (DELTA) are useful predictors of water use efficiency (WUE), drought resistance, evapotranspiration (ET) and salinity tolerance but the relevance to turfgrass cold hardiness has not been determined. DELTA analyses may enable more efficient screening protocols in breeding for improved cold hardiness. Objectives of this study were to examine perennial ryegrass genotypes in relation to cold hardiness, DELTA and WUE in response to WW and WB irrigation schedules, to compare genetic diversity between top-performing (TP) and bottom-performing (BP) perennial ryegrass genotypes, and to assess the predictive value of DELTA of for cold hardiness. Six genotypes were selected based on turf quality from the most northern NTEP location (Orono, ME) and included three TP (‘All Star 2’, ‘Mach I’ and ‘Sunkissed’) and three BP (‘APR-1234’, ‘Buccaneer’ and ‘WVPB-R-82’) genotypes. ET, yield, WUE, shoot water content, rooting potential, wilting tendency, DELTA and median lethal temperatures (LT50) using whole-plant survival were measured from greenhouse samples grown in weighing lysimeters in 2007 and 2008. Plant measurements in both years were based on sampling conducted at the last cycle after 68-d of irrigation with 100% of ET applied at leaf-roll (WB) versus ET replacement every 4-d (WW). Lower LT50 values were generally associated with low yield, low WUE and low shoot water content, whether the result of irrigation treatment or genotypic variation. TP genotypes demonstrated significantly lower LT50 temperatures (greater cold hardiness) in comparison to BP genotypes in both years. Modest cold hardiness enhancement with WB irrigation was highest for TP genotypes. Wilting tendency and DELTA were not reliable predictors of cold hardiness, although individual TP genotypes exhibited responses distinctly different than some BP genotypes. Further research is needed to investigate the physiological mechanisms of enhanced turfgrass cold hardiness in response to moisture stress.

Quinclorac controls crabgrass (Digitaria spp.) post-emergence in cool- and warm-season turfgrass. A rate response study revealed that two Mississippi smooth crabgrass (Digitaria ischaemum) species (MSU1 and MSU2) are resistant to quinclorac. Following that, field experiments were carried out to evaluate programmatic approaches to control one of these populations. Despite prior study on quinclorac-resistant weeds, to date, quinclorac-resistant smooth crabgrass and its mechanism of resistance have only been reported once in California. The mechanism of resistance of MSU1 and MSU2 relative to susceptible (SMT) was then investigated. The SMT biotype accumulated three times more cyanide than the resistant populations. Glutathione-S-transferase (GST) activity was evaluated as a possible contributor to non-target site resistance. The GST activity was elevated in the MSU1 and MSU2 populations. These findings suggest a non-target site–based mechanism of resistance involving the accumulation of cyanide. Further research is needed to investigate potential target-site mechanisms of resistance.

<p>Germination testing and seedling vigor for Kentucky bluegrass germination. Analyzing growth from Kentucky bluegrass cultivars. </p>

Annual grassy weeds are problematic in intensively managed turfgrass systems due to a lack of selective and affordable control options. Four projects were conducted from 2020-2023 to evaluate novel techniques for Annual bluegrass (Poa annua L.), goosegrass (Eleusine indica L. Gaertn.), and smooth crabgrass (Digitaria ischaemum Schreb.) control on golf course putting greens or putting green surrounds. Hybrid bermudagrass Cynodon transvaalensis Burtt. Davy. x dactylon L. Pers.) tolerated cumyluron regardless of application timing, endothall when applied during full dormancy, and methiozolin when applied during mid-transition. Methiozolin half-life in the upper 2-cm of 12 hybrid bermudagrass putting greens was approximately 14 days and was prolonged in similar studies by seven orders of magnitude when herbicide was applied to bare ground compared to adjacent Kentucky bluegrass (Poa pratensis L.) turf. In a study conducted in Alabama, California, Florida, and Virginia, methiozolin at labeled use rates applied biweekly controlled smooth crabgrass >80% in creeping bentgrass (Agrostis stolonifera L.) and hybrid bermudagrass turf. Although similar programs also controlled goosegrass, acceptable control required more applications than are allowed on the product label. Targeted application devices (TAD), such as spot sprayers and dabbers that are used for individual plant treatment of escaped weeds, were tested for uniformity of fluid delivery. Fluid output of dabbing devices was highly variable and dependent on reservoir fill level, reservoir air seal, human user, and contact time, but largely independent of peak force exerted during the dabbing event. These studies suggest that new products are available to improve annual grassy weed control in turfgrass systems, but proper application timing and device calibration is important to achieve best results. / Doctor of Philosophy / Annual grasses are difficult to control in "high-end" golf turf because few herbicides can be safely used near greens and key weeds have become resistant to the most common products. Several new products were tested for safety on hybrid bermudagrass greens. Methiozolin (PoaCure) was safe for use after post-dormancy greenup, endothall was safe when used while turf was still dormant, and cumyluron was safe regardless of application timing. The duration of preemergence weed control with methiozolin is reduced as temperatures increase and in turfgrass compared to bare ground systems. Half of the methiozolin product will dissipate in 14 days or less when applied to hybrid bermudagrass putting greens or Kentucky bluegrass lawns in spring. Methiozolin controlled smooth crabgrass for the entire season in several Southeastern states, but goosegrass control was slightly below acceptable levels when the product was used within annual dose restrictions. Applicators, such as dabbers and spot sprayers, that are used to treat individual plants improve turf safety and reduce chemical cost, but these devices had not been previously tested for uniformity of fluid output. Studies found that these devices can vary in output by several orders of magnitude depending on the type of devices used, the person using the device, and duration of contact with the turf as the user presses a dabbing device over a weed. Within-device errors were equally problematic and governed by the amount of downward pressure exerted by the fluid contained in the device reservoir. For every 10% of fluid capacity added, fluid dispense rate increases approximately 33%. When the air seal of the fluid fill cap is broken, fluid output approximately doubles compared to when this seal is maintained because loss of vacuum increases downward force of the fluid column. These studies suggest that new products are available to improve annual grassy weed control in ornamental turf, but proper application timing and device calibration is important to achieve best results.