ASHS 2024 Conference

Aesthetically appealing and ecosystem servicing turfgrass lawns require proper nutrition and adequate water, which are generally provided by fertilization and supplemental irrigation. However, mismanaged fertilizer and irrigation practices can lead to nutrient losses to the environment, especially nitrogen (N). Model simulations suggest that as the age of the turf stand increases it may be possible to reduce N fertilization and still maintain acceptable turf quality. This is likely due to increases in soil organic matter with turf maturation, which has the potential to provide plant-available N. However, little research has been performed on carbon (C) sequestration and N mineralization in urban residential soils in Florida. It is hypothesized that as lawn age increases it will result in greater C sequestration, microbial activity, and N mineralization. This study was conducted at Lakewood Ranch, FL. Soil samples were collected from lawns with the following ages: 1, 3, 5, 10, 15, and 20 years old. The soil samples were sieved, homogenized, and air-dried prior to soil analysis. Soil analysis included soil organic matter (loss-on-ignition), microbial activity (potentially mineralizable C), and N mineralization (potentially mineralizable N). Data was subjected to analysis of variance (ANOVA) and treatment mean comparisons were separated using Fisher's least significant difference (LSD) at the p ≤ 0.05 level. Lawn age had an impact on soil organic matter, microbial activity, and N mineralization. In general, as a lawn ages, especially after 5 years, it increases the soil organic matter, microbial respiration, and N mineralization. This is the first-year data and a second year with multiple locations will be evaluated to confirm results. Future studies will involve optimizing fertilizer and irrigation recommendations for lawns of various ages.

Turfgrass areas and golf industry have been under scrutiny for their potential impact on the environment, but more environmentally friendly organic fertilizers are increasingly being used to reduce and replace some inorganic fertilizers. A study was conducted on an 8-year-old ‘Tifeagle’ ultradwarf bermudagrass green mowed daily at 0.125 in. located at the University of Florida’s Fort Lauderdale Research and Education Center, Davie, FL to evaluate the effect organic fertilizers and biostimulants on turfgrass performance of Tifeagle’ bermudagrass green. Treatments included: a) XP Stress Rx (applied at 6 6 fl oz./1000 sq. ft.); b) XP-N Stress Rx (applied at 6 6 fl oz./1000 sq. ft.); XP-N Stress Rx Nautilus NuRelease (applied at 6 6 6 0.35 fl oz./1000 sq. ft.). Initial treatment was applied on June 1, 2023, with subsequent applications every 14 days for a total of nine applications. Data was collected every two weeks until three weeks after final application. Turf quality was measured on a 1-9 scale with 9=dark green dense turf, 1=dead/brown turf, and 6=minimally acceptable turf; Normalized Difference Vegetation Index (NDVI) was assessed using a RapidSCAN CS-45; percent green cover and Dark Green Color Index (DGCI) were assessed through Digital Image Analysis of one image taken per plot; volumetric water content was measured at a 3-inch depth using a time domain reflectance sensor. During the summer turfgrass quality, NDVI and DGCI were affected by treatment applications during five of the rating days. Overall, turfgrass fertilized with XP Stress Rx, XP-N Stress Rx and XP-N Stress Rx Nautilus NuRelease showed a higher quality, NDVI and DGCI compared to the unfertilized. Volumetric water content was affected by treatments only after the first application, and no differences were found thereafter. When temperature dropped, and up to three months after last application, biostimulants had a tremendous effect on ultradwarf bermudagrass health preventing the grass from Curvularia spp. infection and helping turfgrass maintaining quality and functionality through the winter.

Cynodon dactylon (L.) Pers. is frequently used as turf and to cross with C. transvaalensis Burtt-Davy in the creation of F1 hybrid cultivars that are widely used on home lawns, golf courses, and sports fields worldwide. However, molecular information associated with adaptive and morphological traits in this species is limited. Accordingly, the objectives of this study were to identify genomic regions associated with establishment rate, spring green-up, drought response, leaf length and width, and stem internode length and width. In this study, we used a ‘A12359’ common bermudagrass high-density linkage map constructed with 3,544 markers. A total of 130 first-generation selfed progeny were evaluated in the field for two seasons for adaptive and morphological traits. A total of 36 genomic regions were identified to be associated with morphological, adaptive, and reproductive traits . The results provide important genetic resources towards understanding the molecular information associated with target traits as well as provide a foundation for using marker-assisted selection in bermudagrass breeding.

Silvery thread moss (Byrum argenteum Hedw.) and others are considered cosmopolitan weeds of creeping bentgrass (Agrostis stoloniferous L.) golf putting greens. These putting green surfaces are vulnerable to moss infestations due to low mowing height, plant growth regulator applications, and restricted nitrogen all required for maintenance. On the actual putting surface, moss interrupts both golf ball roll and visual aesthetics. As a bryophyte, moss is a primitive photosynthetic plant without true leaves or roots and reproduce both sexually (sporophyte) and asexually (fragmentation). Early detection in putting greens is difficult because the protonema (the early stage of moss) resemble blue-green algae or Cyanobacteria. Once established, mosses can tolerate a range of environments from cool-to-hot, and wet-to-dry. Thus, mosses are a chronic problem of creeping bentgrass putting greens. In the past decade, the herbicide carfentrazone (QuickSilver; FMC Corp., Philadelphia, PA) has become the dominant strategy to suppress moss in putting greens, but requires multiple spray applications for efficacious control. In 2023 and 2024, a field study was conducted using a 25-year-old ‘L-93’ plus ‘Providence’ creeping bentgrass nursery green at North Shore Country Club (Glenview, IL). The objective was to explore moss control by two new granular products: Fiesta (chelated iron) and Castaway (tea saponin), both from The Andersons Inc. (Maumee, OH). Granular treatments at product label rate and QuickSilver at 3.35 fl oz/A were applied every 14 days for a total of 8 applications. QuickSilver was applied using a CO2-powered backpack sprayer operated at 40 psi with a three nozzle boom of XR TEEJET 8004VS applied in 2 gal water carrier/1000 sq ft. Year one evaluated granular products versus QuickSilver. Year two compared an additional standard of a once-applied spot treatment of baking soda (sodium bicarbonate) in solution. Both trials were arranged as a randomized complete block design with four replications per treatment. In 2023, Untreated, QuickSilver, Castaway, and Fiesta were evaluated. In 2024, two additional treatments were included of ½ rate Fiesta, and baking soda.. The results indicate that both Castaway and Fiesta granular products were capable of moss suppression in a putting green. Moss control with Fiesta was similar to the QuickSilver herbicide standard or spot treatment by baking soda. Therefore, these granular products could be used alone or in rotation with QuickSilver to control moss in golf course putting greens

Coastal regions, facing saltwater intrusion due to overpumping, exacerbate challenges for turf managers facing soil salinization, and sodium and bicarbonate hazards. Given the prevalence of gypsum applications to counter sodium hazard and the utilization of acidifying fertilizers for neutralizing bicarbonate hazards, there is a need to comprehensively evaluate the effectiveness of these strategies in alleviating soil salinity and bicarbonate hazards and their impact on turfgrass performance. An 8-week study was conducted at the University of Florida’s Fort Lauderdale Research and Education Center to assess the impact of ammonium sulfate and calcium nitrate, either alone or in combination with gypsum, on turfgrass performance and soil properties of a ‘Celebration’ bermudagrass fairway under salinity conditions. To replicate high salinity conditions, table salt (NaCl) was applied to half of the area at a rate of 5 lb of NaCl 1000 ft-2, with the rest of the area serving as a control. Gypsum was applied at a rate of 230 lb gypsum 1000 ft-2 and divided in two applications at mid-point (week 3) and prior to completion of the study (week 7). Fertilizers were applied at a rate of 0.5 lb N/1000 ft2. Salt and fertilizer were applied every two weeks, alternating between each other, for a total of four applications each. Experimental design was a split-split-split design with four replications, with salt serving as a main plot, gypsum as a sub-plot and fertilizer treatment as a sub-sub-plot. Turfgrass visual quality (1=worst, 9=best), normalized difference vegetation index (NDVI), percent green cover, and dark green color index (DGCI), turf injury, volumetric water content (VWC) and electrical conductivity (EC) were assessed weekly. Gypsum had no effect on turfgrass performance. Plots fertilized with AMS initially showed a higher quality than plots fertilized with calcium nitrate after fertilization, however no differences were found toward the end of the trial. Salt reduced turfgrass quality, NDVI and percent green cover and resulted in turfgrass injury, particularly following initial applications. However, it appears that the turfgrass gradually adapted to the salinity conditions, as turfgrass injury from salt decreased during the second half of the experiment. Volumetric water content and EC were affected by the interaction of salt and gypsum. During the experiment, plots treated with gypsum and salt consistently exhibited higher VWC and EC compared to plots that did not receive gypsum. Results suggest that disproportioned amounts of gypsum to improve turfgrass performance applied to golf courses are not justified.

Cold hardiness, flowering, and disease resistance of ornamental camellia (Camellia spp.) cultivars are poorly documented when grown in a climate subjected to occasional -18°C (0°F) temperatures. To comprehensively understand cold-hardiness, flowering, and disease resistance, 24 cultivars and selections of camellia species and hybrids were evaluated in McMinnville, TN, USA (USDA Hardiness Zone 7a). Camellias were planted in field plots in Mar 2011, evaluated for flowering from year 2011 to 2020, and rated for low-temperature damage in 2014 and 2023. The Camellia Yellow Mottle Virus, monochaetia leaf spot (Monochaetia sp.), edema, flower blight (Ciborinia camelliae), and flower spot (Botrytis cinerea) severity (% affected) were evaluated from Oct to Nov in 2016 and 2017, and the season-long area under the disease progress curve (AUDPC) was calculated. ‘April Remembered’, ‘April Rose’, ‘Arctic Snow’, ‘Ashton’s Ballet’, ‘Autumn Carnival’, ‘Autumn Spirit’, ‘Elaine Lee’, ‘Survivor’, and a C. chekiangoleosa selection were least affected by low winter temperatures, whereas ‘Korean Snow’, ‘One Alone’, a C. sasanqua selection, ‘Pink Icicle’, and ‘Shishigashira’ were severely damaged. Cultivars that flowered most reliably (5 to 6 of 8 years) included ‘Arctic Snow’, ‘April Remembered’, ‘April Rose’, ‘Ashton’s Ballet’, ‘Autumn Spirit’, and ‘Survivor’, whereas ‘Maroon Mist’, ‘One Alone’, and ‘Shishigashira’ never flowered. ‘Korean Fire’, ‘Classic Pink’, ‘Maroon Mist’, and ‘Spring’s Promise’ displayed the highest virus severity and AUDPC. ‘Arctic Snow’, a C. sasanqua selection, and a C. chekiangoleosa selection had no viral symptoms. A C. sasanqua selection and ‘Red Aurora’ were significantly impacted by edema disorder, with severity ratings of ∼43% and 26%, respectively. Monochaetia leaf spot severity was highest in ‘Red Aurora’ and ‘Spring’s Promise’, whereas ‘Anacostia’, ‘Arctic Snow’, ‘Ashton’s Ballet’, ‘Autumn Spirit’, ‘Classic Pink’, ‘Kuro Delight’, ‘One Alone’, ‘Pink Icicle’, ‘Shishigashira’, and ‘Survivor’ exhibited the least monochaetia leaf spot severity and AUDPC. Flower blight and flower spot were observed only in ‘Arctic Snow’ and ‘Survivor’. These findings will aid landscapers and nursery growers with selecting and managing camellia cultivars effectively.

The American Rose Trials for Sustainability® (A.R.T.S.®) is a US rose trialing program in its eighth year of announcing winning roses. A.R.T.S.® evaluates newer roses in the marketplace using scientific methodology (blocking, randomization, control cultivars, etc.). Roses are evaluated over two growing seasons and are grown using minimal inputs (i.e. no pesticides, no deadheading, etc.). Entries that score equal to or higher than the control cultivars (Double Knock Out® [‘RADtko’] and Sunrise Sunset™ [‘BAIset’]) and have >50% survival by the end of the trial period, earn regional Local Artist awards. Roses winning in four or more Köppen climate regions earn Master Rose awards. The 2025 award winning roses were planted in 2022. Data was collected monthly during the 2022 and 2023 growing seasons on floral attributes (42.5% of score), foliar health and quality (45% of score), and growth habit (12.5% of score). There were six trial sites representing five US Köppen climate regions (Cfa, Csa, Dfa, Dfb, and H). Five roses won 2025 A.R.T.S.® Local Artist awards: Arctic Blue™ (‘WEKblufytirar’; Csa), Easy to Please™ ('WEKfawibyblu'; Cfa), Pretty Polly® Lavender (‘ZLEpolthree’; Dfa), Sunset Horizon™ (‘MEIsistoma’; Dfa and Dfb), and True Bloom™ True Friendship™ (‘ALTmine’; Csa and Dfa). Performance data will be provided by region for the two control and five winning rose cultivars.