International Turfgrass Society Research Journal最新文献

Incorporating clover into lawns may reduce fertilizer applications and improve pollinator forage; however, much of the recent research has focused on white clover (Trifolium repens), while other clovers have not been as widely researched. White, strawberry (Trifolium fragiferum), crimson (Trifolium incarnatum), and rose (T. hirtum) clover grown as dicultures with Kentucky bluegrass (Poa pratensis) were tested in a greenhouse study under nonfertilized and nitrogen (N) fertilized conditions to determine their influence on soil and aboveground turfgrass and clover tissue N status compared to nonfertilized and fertilized Kentucky bluegrass monocultures. Soil total N, nitrate, and ammonium were not impacted by clover species additions, though N fertilization did impact soil total N. Aboveground white clover tissue in nonfertilized pots had more total N than all other clover tissues in nonfertilized pots, while white clover and strawberry clover tissues in fertilized pots had more total N than crimson and rose clover tissues in fertilized pots. Total N of aboveground turfgrass tissue in fertilized pots was greater than that of aboveground turfgrass tissue in all nonfertilized clover dicultures and Kentucky bluegrass monocultures. Association with different clover species did not affect N content of tissue, while N fertilization impacted turfgrass N status more than association with clover species.

Turfgrass breeders regularly release new cultivars with documented improvements in aesthetics, playability, and stress tolerance for golf turf fairway use. However, complete renovation of the existing fairway results in significant losses of recreational play and potential revenue. Field experiments were conducted on mixed cool-season species fairway to evaluate the potential for grass conversion programs using either no chemical suppression or reduced-impact chemical suppression programs compared to complete renovation. Chemical-treated main plots were vertically mowed and seeded to subplots of creeping bentgrass (Agrostis stolonifera ‘Piranha’), tall fescue (Schedonorus arundinaceus ‘Super Sonic’), or perennial ryegrass (Lolium perenne ‘LS Brand’) at 49, 490, and 490 kg pure live seed ha⁻¹, respectively, and monitored regularly for 1 year to assess multispectral reflectance and visually perceived playing condition. Results suggest that aggressively suppressing vegetation on low-input golf fairways has drawbacks for both playing conditions and the health and density of turf, as measured by ratio vegetation index (RVI) and normalized differential vegetation index (NDVI), consistent with previous studies. Over a 1-year period, perennial ryegrass generally outperformed tall fescue and creeping bentgrass in conserving RVI, NDVI, and golf fairway turf quality and improving dark green color index when lethal chemical rates were used to enhance seed establishment. An unconventional approach involving a combination of trinexapac-ethyl and a sublethal dose of glyphosate, not previously documented in scientific literature, reduced chemical impacts on these metrics and produced comparable improvements to RVI and visual turf quality after 1 year compared to lethal vegetation suppression.

Across the United States and much of the globe, turfgrass is managed at a multitude of scales and requires new technology for efficient monitoring and management. The introduction of unmanned aerial systems (UAS) provides researchers with readily available red–green–blue (RGB) cameras with high-resolution capabilities, which may add considerable value to researchers and producers when assessing turfgrass performance. A study was conducted at the Ft. Lauderdale Research and Extension Center (FLREC) in Davie, FL in the spring (February–April) of 2023 to evaluate the performance of RGB vegetation indices (VIs) on ‘Celebration’ bermudagrass [Cynodon. Dactylon (L.) Pers.] and ‘CitraBlue’ St. Augustinegrass [Stenotaphrum secundatum (Walt.)] in comparison to visual ratings and Normalized Difference Vegetation Index (NDVI). Images were obtained by an RGB camera coupled to a remotely piloted Parrot ANAFI Thermal drone capturing images with 75% overlap. Both the Green Leaf Index and Green Chromatic Coordinate were highly correlated to quality readings in both grasses, with correlation coefficients as high as 0.92 in bermudagrass (outcompeting NDVI) and 0.88 in St. Augustinegrass (NDVI was more correlated). Each grass species had a unique correlation with each index, showing how different species and possibly cultivars may be better monitored with species-specific VIs.

The pacific shoot-gall nematode (Anguina pacificae) is a serious pest of annual bluegrass (Poa annua) putting greens in coastal Northern California. Until recently, there have been relatively few effective plant protectant compounds against this endoparasitic nematode that infects shoots. This study evaluated the efficacy of cyclobutrifluram, which targets the mitochondrial succinate dehydrogenase complex of nematodes and fungi. Three studies were conducted from 2021 to 2024 at TPC Harding Park Golf Course in San Francisco, CA. Cyclobutrifluram was applied alone at a rate of 125, 250, or 500 g a.i. ha⁻¹ or in combination with abamectin applied at 360 g a.i. ha⁻¹ (3.9 g L ha⁻¹ of product). Fluopyram applied at 500 g a.i. ha⁻¹ (1.25 L ha⁻¹ of product) was included as a standard. Cyclobutrifluram significantly improved turfgrass visual quality and reduced nematode injury compared to the untreated control, and overall effects were comparable to fluopyram. Tank mixtures or rotations with abamectin did not increase efficacy unless nematode pressure was high. These findings suggest that cyclobutrifluram is an effective plant-protectant compound for managing pacific shoot-gall nematodes.

The goal of this study was to begin developing a methodology with which individual golf courses can measure their soil organic carbon (SOC) stocks and sequestration. We propose a two-tiered methodology that starts with the space-for-time substitution method but then graduates to the longitudinal method. Space-for-time allows golf courses to compare their SOC stock to the SOC stock of the surrounding land use, whereas the longitudinal method provides a high-resolution carbon sequestration estimate after 5 years. The first tier of this methodology was tested on two golf courses that are part of the same golf facility in the United Kingdom. The two golf courses and the agricultural fields adjacent to them, which also represented the historical land use of the golf courses, were sampled to determine their SOC stocks. We recognize that the SOC stock trajectories of the golf courses and neighboring crop fields are unknown, and thus we do not use the term carbon sequestration to describe the differences in carbon stocks between the two land uses. Instead, we use the term counterfactual carbon storage to describe that the SOC stock of the surrounding agricultural fields was the best available representation of what the SOC stock of the land the golf courses are now on would have been had the golf courses not been built. We found the golf courses had higher SOC stocks than the surrounding agricultural fields, which corresponded to 0.41 and 0.77 Mg C ha⁻¹ year⁻¹ more carbon in the soils of the golf courses than on the surrounding agricultural fields. Maintenance emissions from the time of construction to the present were also estimated to calculate the lifecycle net climate impact of the golf courses. Our results highlight the importance of emissions reductions if golf courses are to be carbon neutral throughout their lifecycle.

Water use by turfgrasses is important because it impacts land use decisions and the potential use of natural turfgrasses in enclosed stadia due to humidity levels and fan comfort. The application of exogenous abscisic acid (ABA) has been shown to reduce evapotranspiration (ET) and photosynthetic rates of plants. This study aimed to examine the impact of foliar ABA application on Kentucky bluegrass (KBG; Poa pratensis) ET and photosynthetic rates. In addition, water use efficiency (WUE), turfgrass growth, and percent green cover before and after application were also measured. The application of ABA reduced KBG ET and photosynthetic rates by 19.2% and 18.2%, respectively, while also reducing turfgrass growth and greenness. Photosynthetic rates returned to normal during recovery periods, whereas ET rates did not return to pre-drought levels. The response of ET and photosynthetic rates did not provide a consistent response, although WUE was reduced immediately after ABA application. These findings show reductions in ET rates that could affect conditions in indoor stadia, which may provide insight for turfgrass maintenance of indoor stadia with turfgrasses.

The Portable L-band Radiometer (PoLRa), or “turfRad,” was recently introduced to turfgrass as a potential alternative to existing soil moisture measurement technologies, offering large-scale, frequent, and robust data collection essential for high-resolution mapping and precision irrigation. However, PoLRa measurements can be influenced by soil and environmental factors, possibly requiring site-specific calibrations for accurate soil moisture estimation. This study evaluates the “off-the-shelf” accuracy of a PoLRa unit and explores analysis of covariance (ANCOVA) regression modeling for calibration. Three fairways at Champions Golf Club's Jackrabbit Course in Houston, TX, were monitored over four surveys using the PoLRa, with ground-truth measurements collected at 12 locations per fairway using time domain reflectometry. Off-the-shelf calibration resulted in an R² value of 0.36 (p < 0.01), with a mean absolute error (MAE) and root mean square error (RMSE) of 0.08 and 0.09 m³ m⁻³, respectively. Incorporating PoLRa brightness temperature in vertical polarization into the ANCOVA model improved the R² to 0.82 (p < 0.01) and reduced the MAE and RMSE to 0.02 m³ m⁻³, reflecting a significant improvement in model accuracy. These results, for the first time, report the ability of PoLRa to accurately map soil moisture on golf courses. The results, however, strongly suggest that site-specific calibrations are needed. The ANCOVA regression approach was an effective means of developing site-specific calibration. Future research should focus on integrating additional edaphic factors (e.g., soil texture) and agronomic factors (e.g., different varieties and management practices) while testing across various climatic environments to further evaluate PoLRa sensing for irrigation management on golf courses.

Winter damage of golf turf in northern environments is a persistent challenge, and reseeding is often necessary to promote recovery and to maintain adequate density and uniformity for play. However, adverse conditions associated with spring seedings can negatively impact reestablishment of creeping bentgrass (Agrostis stolonifera L.) (CBG) on golf greens, tees, and fairways. The objectives of the research were to examine different strategies to promote rapid reestablishment of CBG in early spring, including cultivar selection, use of a synthetic cover, and application of plant health products. To assess the impacts of CBG cultivars and cover on reestablishment, 12 cultivars and two cover treatments (without or with a permeable synthetic cover) were established at two locations in 2021 (South Deerfield, A, and Saint Paul, MN). The effects of plant health products on CBG establishment were assessed in separate field trials at two locations in 2021 and 2022 (South Deerfield, MA, and Grimstad, Norway). Plant health product treatments were applied on a weekly basis following emergence and included: control (water), chitosan, silica, acibenzolar S-methyl, glycine betaine, seaweed extracts (alone or together with humic substances), trinexapac-ethyl, and gibberellic acid. Soil and air temperatures were monitored, and plots were visually assessed for changes in percent green turfgrass cover. The use of a permeable cover increased soil temperatures and decreased the time to achieve 50% turfgrass cover by 7–12 days, depending on location and regardless of cultivar. Compared to effect of covering treatment, most CBG did not significantly vary in spring establishment rates, except for Independence, which exhibited slower establishment. Among the various plant health products tested over 2 years and two locations, we did not identify any specific product that consistently enhanced early spring establishment of CBG.

Creeping bentgrass (Agrostis stolonifera L.) is a popular turfgrass species used on golf courses. It is routinely grown on putting greens and tees that are surrounded by trees, which exposes bentgrass to shaded conditions and results in physiological changes in the plant that can reduce quality, playability, and performance. The objective of this study was to identify traits that may be associated with shade tolerance in creeping bentgrass and identify cultivar responses to simulated foliar shade versus non-shaded conditions. Greenhouse and growth chamber studies were utilized to evaluate 41 commercial cultivars and experimental selections arranged in a completely random design with four replications. Simulated shade was provided by a photoselective filter to reduce the red to far-red ratio (R:FR) by ∼33% (R:FR ∼0.86) and decrease the light intensity by ∼50% compared to non-shaded conditions. Traits measured were plant height, tiller count, height to tiller ratio, biomass, chlorophyll content, and turf quality ratings. Digital images were also collected. Plant height and chlorophyll content were significantly affected by light condition, and differences in these traits were observed among creeping bentgrass cultivars across the four experiments. Cultivars with a small percent change in height in simulated shade compared to no shade were L93XD, 007XL, Piranha, and Oakley. Cultivars with a large change in height under shade (higher under shade) were PennA4, Tyee, and PinUp. These cultivars would not be recommended for shaded sites. Cultivars with large increased changes in chlorophyll content were Matchplay and MacDonald, whereas the cultivar PennA4 and the experimental selection LPD15 had little change in chlorophyll concentration between shade and non-shaded conditions. Principal component analysis revealed that turf quality under shade is associated with moderate increases in tiller number and chlorophyll content and smaller changes in plant heights. Cultivars that possess these traits, such as L93XD, 007XL, and Chinook, would be good choices for shaded environments. This research identified significant variation in cultivar response to simulated foliar shade and indicated that cultivar choice should be considered when planting in shaded environments.

Bermudagrass (Cynodon dactylon) and interspecific hybrids of bermudagrass (C. dactylon × C. transvaalensis) are the predominant turfgrasses used for athletic, commercial, and residential urban ground cover in temperate areas. In regions where bermudagrasses enter a cold temperature–induced dormancy during winter months, the disease spring dead spot (SDS) is often the most devastating and important disease of this turfgrass. The disease is caused by three closely related fungi in the genus Ophiosphaerella. In this multiyear study, the influence of nitrogen (N) at 0, 73.2, 146.5, 220, and 293 of N kg ha⁻¹ and the influence of potassium at 0, 48.8, 97.7, and 146.5 kg K ha⁻¹ per year were evaluated to determine if there was an influence on disease severity. Two cultivars, Patriot and U-3, were evaluated with four replications, and both cultivars were arranged in a split–split block design for all nitrogen and potassium treatments. Plots were inoculated in 2012 with Ophiosphaerella herpotricha, and disease severities were evaluated over 5 years starting in 2015, utilizing digital imaging and Access software. In 2015, N had an influence on disease for both cultivars with 0 N plots having the majority cases of disease, and there were no differences for N applications above that rate for both cultivars. In 2015, for U-3, the highest rate of K had greater disease severities than the lower two rates. In 2019, U-3 plots not fertilized had higher chance of disease than those plots treated at 293 of N kg ha⁻¹. Disease severities for both cultivars regardless of fertility inputs dramatically declined over time, most likely due to climate warming as occurrence and severity of this disease requires cold temperatures.