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Friday, September 27
 

9:00am HST

Guiding Nitrogen Fertilization for Turfgrass: Moving from Subjective Guessing to Objective Testing
Friday September 27, 2024 9:00am - 10:00am HST
Speaker: Dr. Karl Guillard
Nitrogen fertilization for higher-cut turfgrasses such as lawns, parks, institutional grounds, etc., typically follows long-standing practices that have not changed much in the last several decades. Fertilizer applications are generally made at predetermined rates [usually around 1 lb N per 1,000 sq. ft (49 kg N per hectare)] on or around benchmark calendar dates or events throughout the growing season, e.g., Easter, Memorial Day, Labor Day, Thanksgiving Day. Depending on turfgrass species and intended use, fertilization can occur once to four times or more during the growing season. The rates and timing are common across wide ranging geographical locations, soils, and climate conditions. From a scientific perspective, this is not logical and suggests that the current fertilization approach is subjective and essentially guessing. Sometimes the turfgrass manager will guess the appropriate rate correctly, but there is a high probability that the rate will not be optimum and either higher or lower than what the turfgrass stand needs to meet growth, performance, and/or aesthetic goals. In this talk, I will review the past and current work from my laboratory researching new soil tests, sap nitrate tests, and reflectance meters to objectively guide and improve nitrogen fertilization of higher-cut turfgrasses.

Friday September 27, 2024 9:00am - 10:00am HST
Coral 5 - ASHS Hort Theater

12:14pm HST

Ornamentals/Landscape and Turf 2 (O/LT 2)
Friday September 27, 2024 12:14pm - 1:25pm HST
Impact of Lawn Age on Soil Organic Matter, Microbial Respiration, and Nitrogen Mineralization - Alex Lindsey
Effect of Organic Fertilizers and Biostimulants on ‘TifEagle’ Bermudagrass Greens - Marco Schiavon
Detection of QTL Associated with Morphological, Adaptive, and Reproductive Traits in Common Bermudagrass - Shuhao Yu
Alternate Products to Control Silvery Thread Moss in a Creeping Bentgrass Putting Green - Shehbaz Singh
Evaluation of Gypsum and Fertilizers for Enhanced Bermudagrass Performance Under Salinity Conditions in Florida Sandy Soils - Idalia Sierra
Cold-hardiness, Flowering, and Disease Resistance of 24 Camellia Cultivars and Selections in Tennessee, USA - Jacob Shreckhise
The American Rose Trials for Sustainability® (A.R.T.S.®) Program Announces Five Winning Roses for 2025 - Kristine Lang

Moderator
SY

Shuhao Yu

Oklahoma State University
Friday September 27, 2024 12:14pm - 1:25pm HST
Coral 2

12:15pm HST

O/LT 2 - Impact of Lawn Age on Soil Organic Matter, Microbial Respiration, and Nitrogen Mineralization
Friday September 27, 2024 12:15pm - 12:25pm HST
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.
Speakers
AL

AJ Lindsey

University of Florida
Friday September 27, 2024 12:15pm - 12:25pm HST
Coral 2

12:25pm HST

O/LT 2 - Effect of Organic Fertilizers and Biostimulants on ‘TifEagle’ Bermudagrass Greens
Friday September 27, 2024 12:25pm - 12:35pm HST
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.
Speakers
MS

Marco Schiavon

Assistant Professor, University of Florida
Co-authors
AS

Alejandra Sierra

University of Florida
Friday September 27, 2024 12:25pm - 12:35pm HST
Coral 2

12:35pm HST

O/LT 2 - Detection of QTL Associated with Morphological, Adaptive, and Reproductive Traits in Common Bermudagrass
Friday September 27, 2024 12:35pm - 12:45pm HST
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.
Speakers
SY

Shuhao Yu

Oklahoma State University
Friday September 27, 2024 12:35pm - 12:45pm HST
Coral 2

12:45pm HST

O/LT 2 - Alternate Products to Control Silvery Thread Moss in a Creeping Bentgrass Putting Green
Friday September 27, 2024 12:45pm - 12:55pm HST
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
Speakers
SS

Shehbaz Singh

Manager of Turfgrass research, Chicago District Golf Association
Co-authors
DS

Derek Settle

Chicago District Golf Association
NA
Friday September 27, 2024 12:45pm - 12:55pm HST
Coral 2

12:55pm HST

O/LT 2 - Evaluation of Gypsum and Fertilizers for Enhanced Bermudagrass Performance Under Salinity Conditions in Florida Sandy Soils
Friday September 27, 2024 12:55pm - 1:05pm HST
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.
Speakers
avatar for I. Alejandra Sierra

I. Alejandra Sierra

University of Florida
Co-authors
MS

Marco Schiavon

University of Florida
Friday September 27, 2024 12:55pm - 1:05pm HST
Coral 2

1:05pm HST

O/LT 2 - Cold-hardiness, Flowering, and Disease Resistance of 24 Camellia Cultivars and Selections in Tennessee, USA
Friday September 27, 2024 1:05pm - 1:15pm HST
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.
Speakers
JS

Jacob Shreckhise

USDA-ARS, U.S. National Arboretum
Co-authors
DF

Donna Fare

USDA-ARS, U.S. National Arboretum (Retired)
NA
FB

Fulya Baysal-Gurel

Tennessee State University
NA
MP

Madhav Parajuli

USDA-ARS, U.S. National Arboretum
NA
Friday September 27, 2024 1:05pm - 1:15pm HST
Coral 2

1:15pm HST

O/LT 2 - The American Rose Trials for Sustainability® (A.R.T.S.®) Program Announces Five Winning Roses for 2025
Friday September 27, 2024 1:15pm - 1:25pm HST
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.
Speakers
avatar for Kristine Lang

Kristine Lang

Assistant Professor and Extension Specialist, South Dakota State University
Co-authors
DZ

David Zlesak

University of WI River Falls
GH

Gaye Hammond

Houston Rose Society
NA
GP

Gregory Pongetti

Arboretum and Botanical Garden at Cal State Fullerton
NA
JS

Jeff S. Kuehny

LSU AgCenter Botanic Gardens at Burden
NA
JC

Jessica Clonninger

Boerner Botanical Gardens
NA
JL

Jessie Liebenguth

Reiman Gardens-Iowa State University
NA
PD

Patrick Dahl

Chicago Botanic Garden
NA
RS

Randy S. Nelson

University of Minnesota- Crookston
NA
RH

Richard Hawke

Chicago Botanic Garden
NA
SM

Shaun Moser

Conservation Garden Park
NA
SG

Steve George

Texas A
NA
SW

Susan Worthey

Magnolia Botanical Garden- Mississippi State University
NA
WE

Wanda E. Ellis

LSU AgCenter Botanic Gardens at Burden
NA
Friday September 27, 2024 1:15pm - 1:25pm HST
Coral 2

2:14pm HST

Ornamentals/Landscape and Turf 3 (O/LT 3)
Friday September 27, 2024 2:14pm - 3:30pm HST
Seedling Zoysiagrass Response to Fluazifop-butyl and Trifloxysulfuron-methyl With the Safener Metcamifen - Hannah Wright-Smith
Influence of Demethylation Inhibiting Fungicides on Creeping Bentgrass Putting Greens - Wendell Hutchens
Endophytic N Fixing Bacteria Isolated From Warm-season Turfgrasses and Common Lawn Weeds - Andrea F Arevalo Alvarenga
Mowing Mediated Root Radial Transport of Lead in Cynodon dactylon (L.) Persoon - Xinyi Cai
Cool-season Turfgrass Biomass and Ecosystem CO2 Flux as Affected by Fertilization and Irrigation - Ruying Wang
The 2023 Arkansas Diamond Plant Evaluation Trials - Anthony Bowden
Moderator
HW

Hannah Wright-Smith

Extension Weed Specialist, University of Arkansas
Friday September 27, 2024 2:14pm - 3:30pm HST
South Pacific 2

2:15pm HST

O/LT 3 - Seedling Zoysiagrass Response to Fluazifop-butyl and Trifloxysulfuron-methyl With the Safener Metcamifen
Friday September 27, 2024 2:15pm - 2:30pm HST
Managing grassy weeds in turfgrass can be challenging. In 2023 a new formulation of trifloxysulfuron-methyl containing the safener metcamifen, Recognition® Herbicide, was commercially available for use in established zoysiagrass. When applied as a mixture, this product safens zoysiagrass from the effects of the graminicide fluazifop-butyl (Fusilade® II Herbicide), allowing for higher application rates of fluazifop-butyl to manage difficult to control grass weeds such as bermudagrass. Previous research has demonstrated acceptable response following this herbicide mixture when applied to established zoysiagrass, however no information is available evaluating seedling zoysiagrass response to these herbicides. Experiments were conducted at the Milo J. Schult Agricultural Research and Extension Center in Fayetteville, AR and the Southwest Research and Extension Center in Hope, AR in 2023 to evaluate seedling zoysiagrass injury from applications of fluazifop-butyl and trifloxysulfuron-methyl with metcamifen applied at two different rates. “Zenith” zoysiagrass was seeded in June and August in Fayetteville and Hope, respectively, with herbicide applications made 2-and 4-weeks after emergence. Similar response was observed from both 2- and 4- week after emergence herbicide application timings. When applied as a mixture to seedling zoysiagrass, treatments of fluazifop-butyl plus trifloxysulfuron-methyl with metcamifen resulted in a maximum of 20% visual injury 1-week after treatment. However, seedling recovery was observed at subsequent ratings with
Speakers
HW

Hannah Wright-Smith

Extension Weed Specialist, University of Arkansas
Co-authors
DN

David Nistler

University of Arkansas
NA
JM

John McCalla

University of Arkansas
NA
LT

Lane Tredway

Syngenta
NA
MD

Michael D Richardson

University of Arkansas
NA
Friday September 27, 2024 2:15pm - 2:30pm HST
South Pacific 2

2:30pm HST

O/LT 3 - Influence of Demethylation Inhibiting Fungicides on Creeping Bentgrass Putting Greens
Friday September 27, 2024 2:30pm - 2:45pm HST
Demethylation inhibiting (DMI) fungicides are frequently applied to turfgrasses for suppression of many common fungal diseases in turfgrass. However, certain DMI fungicides cause phytotoxic effects to turfgrasses, particularly creeping bentgrass (Agrostis stolonifera L.), during the heat of the summer. A study was conducted in Fayetteville, AR in the summer of 2023 to determine the effects of nine DMI fungicides (flutriafol, mefentrifluconazole, metconazole, myclobutanil, propiconazole, prothioconazole, tebuconazole, triadimefon, and triticonazole) compared to a nontreated control on a ‘Pure Eclipse’ creeping bentgrass putting green. All treatments were applied a total of six times at the highest labeled rate at biweekly intervals beginning on 23 Jun 2023 and ending on 1 Sep 2023. A CO2-pressurized backpack sprayer was used to deliver the treatments in a carrier volume of 814 L ha-1. Plots were assessed weekly for percent phytotoxicity (0-100%). Additionally, beginning on 27 Jul 2023, clippings were collected, dried, and weighed weekly until 24 Aug 2023. Data were averaged across all rating dates, subjected to analysis of variance, and means were separated using a Student’s t-test (p < 0.05). Propiconazole caused ≥ 36.7% more phytotoxicity than any other treatment. The only other fungicide treatments that caused greater phytotoxicity than the nontreated control were myclobutanil and triadimefon. Myclobutanil, propiconazole, and triadimefon were also the only treatments to increase clipping weights compared to the nontreated control. These data suggest that many DMI fungicides do not cause phytotoxic effects on creeping bentgrass putting greens during the summer with the exception of myclobutanil, propiconazole, and triadimefon.
Speakers
WH

Wendell Hutchens

Assistant Professor of Turfgrass Science, University of Arkansas
Wendell Hutchens, PhD is an assistant professor of turfgrass science in the Horticulture Department at the University of Arkansas. His main areas of expertise are turfgrass pathology and precision management of turfgrass pests using emerging technologies. His research program is centered... Read More →
Co-authors
JA

Jessica Anders

University of Arkansas
NA
KG

Koa Grabar

University of Hawaii at Manoa
NA
MB

Michael Battaglia

University of Arkansas
NA
Friday September 27, 2024 2:30pm - 2:45pm HST
South Pacific 2

2:45pm HST

O/LT 3 - Endophytic N Fixing Bacteria Isolated From Warm-season Turfgrasses and Common Lawn Weeds
Friday September 27, 2024 2:45pm - 3:00pm HST
The turfgrass industry has attempted to adopt market available N fixing bacterial strains to supply exogenous N requirements. However, turfgrass inoculations with market available N fixing strains have led to inconclusive results. Research on naturally occurring N fixers has mainly focused on abundance and diversity on roots and below ground soil. These ecological niches are known to be impacted by regular management practices of turfgrass which also interfere with the colonization rates of microorganisms. Therefore, the use of endophytic N fixing bacteria which are naturally present in turfgrasses such as bermudagrass, creeping bentgrass, and tall fescue is an attractive alternative regarding a higher microbial stability and potential of colonization. In this study we evaluated the culturing potential of N fixing bacteria from three turfgrass and three common weed species, assayed their potential to grow under different ammonium chloride (NH4Cl ) concentrations, and compared the isolates with the dominant taxa from a previous study in the community composition of N fixing bacteria in ‘CitrablueTM’ St. Augustinegrass [Stenotaphrum secundatum (Waltz)]. The plant biomass was collected from ‘CitrablueTM’, ‘Celebration’ bermudagrass [Cynodon. dactylon (L.)], ‘Empire’ zoysiagrass [Zoysia japonica (Steud)], goosegrass [Eleusine indica (L.) Gaertn], crabgrass [Digitaria sanguinalis (L.) Scoop], and bull paspalum [Paspalum setaceum (Michaux)]. The biomass was washed with water and surface sterilized using consecutive immersions in ethanol 75%, bleach 50%, and three rinses with ultrapure water. After sterilization, N fixers were isolated using a N free enrichment technique with Carbon Combined Media (CCM) and streaking on CCM solid plates. Taxonomy of the isolates was assigned using 16S and nifH Illumina miseq sequencing, consequently, the isolates were grown in liquid CCM with NH4Cl concentrations ranging from 100 uM to 0.001 uM. The isolates, Sphingomonas trueperi, Kosakonia radicitans, Herbaspirillum rubrisulbicans, Agrobacterium salinotolerans, Stenotrophomonas maltophilia, Kosakonia oryzae, Enterobacter sp. were not able to grow below 1 uM of NH4Cl in liquid CCM, however, these strains were the best performing strains because were able to grow at lower NH4Cl concentrations. Lastly, the isolates were not genotype specific to either turfgrasses or weeds and were not correlated with the dominant taxa of N fixers on the ‘CitrablueTM’ study.
Speakers
AF

Andrea F Arevalo Alvarenga

Graduate Assistant, University of Florida
Co-authors
MS

Marco Schiavon

University of Florida
US

Ulrich Stingl

University of Florida
NA
Friday September 27, 2024 2:45pm - 3:00pm HST
South Pacific 2

3:00pm HST

O/LT 3 - Mowing Mediated Root Radial Transport of Lead in Cynodon dactylon (L.) Persoon
Friday September 27, 2024 3:00pm - 3:15pm HST
Moderate mowing has been demonstrated as an effective strategy for aiding soil Pb remediation using bermudagrass. However, the precise mechanisms by which mowing facilitates the absorption and transport of Pb in bermudagrass remain unclear. Radial transport of Pb in roots governs the amount of Pb loaded into xylem vessels, where Pb ions are translocated upward into shoots. This study aims to investigate the radial transport pathways and their characteristics of Pb in bermudagrass under Pb and mowing treatments to elucidate the underlying mechanisms. The results indicate a shift in Pb distribution within the bermudagrass roots under mowing treatments. Specifically, there was a decrease in Pb distribution in the root apoplast accompanied by an increase in the root symplast. Under mowing conditions, the synthesis of abscisic acid and jasmonic acid in roots was significantly induced, leading to a delayed development and deposition of the endodermal barriers (Casparian strips and suberin lamellae). This reduction in the contribution rate of the apoplastic bypass inhibited Pb from entering the stele via the apoplastic pathway. Conversely, mowing pretreatment inhibited Pb absorption in roots but promoted Pb absorption in shoots under treatments with metabolic and ion channel inhibitors. Additionally, Pb2 net influx in the root apex was remarkably enhanced, and the expression of Pb absorption- and transport-related genes (CdNramp5 and CdHMA2) were upregulated following mowing application, suggesting that mowing promoted Pb transport through the symplastic pathway. Overall, this study provides the first evidence that mowing mediates the radial transport of Pb in bermudagrass. Mowing enhances the absorption and root-to-shoot transport of Pb primarily by increasing the efficiency of the symplasmic pathway.
Speakers
XC

Xinyi Cai

University of Georgia
Co-authors
DZ

Donglin Zhang

University of Georgia
XL

Xi Li

Sichuan Agricultural University
NA
Friday September 27, 2024 3:00pm - 3:15pm HST
South Pacific 2

3:15pm HST

O/LT 3 - Cool-season Turfgrass Biomass and Ecosystem CO2 Flux as Affected by Fertilization and Irrigation
Friday September 27, 2024 3:15pm - 3:30pm HST
Concerns about the environmental impacts of lawns, including a high climate footprint, can pose challenges to the acceptance of natural turfgrasses. There are limited assessments of how to enhance turfgrass carbon sequestration and reduce management inputs in turfgrass systems in the northwest U.S. The goal of this study was to evaluate how fertilization and irrigation management can affect the ability of mixed cool-season turfgrass stands to sequester carbon. Annual rates of 0 and 196 kg N ha−1 were evaluated in the fertilization trial, while a non-irrigated control and 0.6 cm of precipitation applied four times per week in the summer months were compared in the irrigation trial. A portable clear chamber with a CO2 gas analyzer was used to measure CO2 fluxes. Grass clippings were collected from each plot to measure dry weight and subsequently returned to their respective plots. Clipping data were summarized as annual clipping production rates. Turfgrass standing biomass was sampled in 2021 and 2022 after summer stress and separated into aboveground (verdure) and belowground (thatch and roots) biomass. Our results indicated that the annual fertilization rate of 196 N ha−1 significantly increased photosynthesis in cool-season turfgrass in the winter and early spring compared to the unfertilized control. Fertilization also increased the net ecosystem exchange (NEE) rate in the winter, but the increases in NEE were less frequently observed than in the photosynthetic rate. Moreover, higher respiration rates were occasionally observed with the fertilization treatment. In contrast, fertilization had little to no effect on NEE, photosynthesis, and ecosystem respiration rates during the summer. Fertilization resulted in higher annual clipping yield, whereas there were no statistical differences between fertilization and no fertilization treatments in above- or below-ground biomass. In the irrigation study, the growth of turfgrass without irrigation ceased during summer as evidenced by reduced photosynthetic rates that were close to 0. Summer irrigation also stimulated ecosystem respiration which offset the benefits of enhanced photosynthetic rates, suggesting that further research is needed to identify the optimum irrigation practice for enhancing net CO2 assimilation. Irrigation produced greater annual clipping production in 2021 but had no effect in 2022. Irrigation was also shown to significantly increase aboveground biomass, but belowground biomass was not affected by irrigation. These results provided a better understanding of cool-season turfgrass growth in the Pacific Northwest U.S. so that cultural practices can be refined for more climate-friendly turfgrass management.
Speakers
RW

Ruying Wang

Oregon State University
Co-authors
AK

Alec Kowalewski

Oregon State University
NA
CM

Clint Mattox

USDA-ARS
NA
EB

Emily Braithwaite

Oregon State University
NA
ZH

Zachary Hamilton

Oregon State University
NA
Friday September 27, 2024 3:15pm - 3:30pm HST
South Pacific 2

3:30pm HST

O/LT 3 - The 2023 Arkansas Diamond Plant Evaluation Trials
Friday September 27, 2024 3:30pm - 3:45pm HST
Arkansas’ research-backed plant assessment initiative known as "Arkansas Diamonds" aims to educate local gardeners on annual bedding plants that consistently thrive in Arkansas's climate. Moreover, it serves to bolster local growers and independent garden centers within the state. Facilitated by the Arkansas Green Industry Association (ARGIA) and the University of Arkansas System Division of Agriculture (UADA), this collaborative effort engages county agents across Arkansas in annual demonstration plots. In 2023, thirty county agents partook in the statewide evaluation of four annual plant species. Each agent received nine replicants of each species and conducted monthly measurements of height, width, flower quality, and overall health. These findings, integral to the selection process, contribute to designating certain plants as "Arkansas Diamonds," signifying their suitability for the state's gardens and green industry. After evaluations, the selected plants are grown by ARGIA members and marketed on a statewide basis to encourage home gardeners and the landscape industry to incorporate these plants into their home landscapes and support the local green industry and independent garden center within the state.
Speakers
AB

Anthony Bowden

University of Arkansas
Co-authors
RF

Randy Forst

University of Arkansas
NA
Friday September 27, 2024 3:30pm - 3:45pm HST
South Pacific 2
 


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