ASHS 2024 Conference

Evaluation of Native Azaleas for Container Production in the Mid-Atlantic - William Errickson
Facilitating Pollinator Conservation in Agriculture: Understanding Grower Needs in Obtaining IPM Certification - Madison Love
Relationship between Soil Water Content, Quantum Efficiency, Stomatal Conductance and Stem Water Potential in Salvia guaranitica ‘Black and Blue’ - Lindsey Trinkle
Effect of Coconut Coir and Biochar Media on Ornamental Plant Growth and Nutrient Leaching - Saroj Burlakoti
Physiological and Morphological Characteristics of Marigold Exposed to Different Ratios of Blue Light and Red Light - Anju Chaudhary
Responses of Three Ornamental Species to Saline Water Irrigation - Zirui Wang
Field Performance of Penstemon Species under Deficit Irrigation - Zirui Wang
Responses of Calamagrostis ×acutiflora under Deficit Irrigation - Zirui Wang

Deciduous azaleas (Rhododendron spp.) are native to the Eastern United States and have potential for increased adoption in the ornamental nursery and landscape market. However, plant availability is currently limited and trials on the growth and performance of each species are lacking. Furthermore, seed propagation is the common production method for native azaleas, which can result in phenotypic variation and a longer period of time to produce a saleable product, relative to vegetative propagation. Under optimum growing conditions, native azaleas can be low-input plants with minimal insect and disease issues. However, they can also be susceptible to summer heat stress and require well-drained soils and partial-shade similar to their indigenous growing environments in order to thrive. To determine which species may be most well-adapted to typical container nursery production practices, container trials were established to evaluate nine different species of native azaleas, including R. arborescens, R. atlanticum, R. austrinum, R. canescens, R. cumberlandense, R. flammeum, R. periclymenoides, R. prunifolium, and R. vaseyi, grown in both full sun and 50% shade conditions. Seed-grown one-year old liners of each of the nine different species were established in one-gallon containers and evaluated for growth rate and physiological characteristics, such as leaf chlorophyll content and normalized difference vegetation index (NDVI), comparing plants grown in full sun vs. 50% shade. In year two, bloom dates and number of blooms per plant in full sun vs. 50% shade were compared. R. atlanticum demonstrated the greatest potential for commercial production, especially when grown under 50% shade conditions, based on growth rate and average number of blooms per plant. These results suggest that R. atlanticum may be a reliable species of native azalea for growers to commercially produce for this growing market segment, while other species may still have potential, albeit with additional attention to their specific production requirements.

Due to global concerns over the decline in pollinator populations, Walmart U.S. has initiated a policy requiring all produce and floral products sold in stores to be sourced from vendors who have obtained an Integrated Pest Management (IPM) certification from an approved third-party organization by 2025. The certification process for growers entails comprehensive documentation of operational practices, pesticide use and mitigation, and evaluation of on-farm pollinator habitat. However, this process is cumbersome for growers to conduct alone, necessitating assistance from a third-party such as Extension agents and staff. Furthermore, identifying and expanding existing pollinator habitat is often unfamiliar to growers, presenting a significant barrier in the application process and hindering the expansion of pollinator habitat. This project seeks to assess the needs of growers in navigating the IPM certification process and understanding the barriers they face. Future work will include the development of accessible consulting services that supports North Carolina growers throughout the certification process while also equipping them with necessary skills and knowledge to enhance and expand pollinator habitat.

Perennials are an important component in north-central Texas landscapes, providing color and foraging for local pollinators. However, severe summer drought and a rapidly growing urban environment forces limitations on water availability for landscape irrigation. Therefore, we need to evaluate the impact of deficit irrigation on landscape plant performance. Salvia guaranitica ‘Black and Blue’ is a perennial known to perform well in north-central Texas summers, and it attracts numerous pollinators, including bumblebees, butterflies, and hummingbirds. Twelve beds were created in four blocks, with three beds per block and one plant planted per bed. Within each block, irrigation was applied at one of three levels, 60% of evapotranspiration (ET), 30% of ET and no irrigation. Soil moisture monitors [time domain reflectometry (TDR), 10HS, Onset Computer Corp., Bourne, MA] and a handheld moisture meter (TDR, Fieldscout 350, Spectrum Technologies, Aurora, IL) were used to measure water content by volume (Θv). Quantum efficiency (ΦPSII) and stomatal conductance (gs) were measured using a fluorometer/porometer (LI-600, LiCor Corp., Lincoln, NE), and stem water potential of each plant was measured using a pressure chamber (Model 615, PMS Instrument Company, Albany, OR) on a weekly basis. Surprisingly, soil moisture levels in the 30% treatment (0.10 m-3·m-3) were the lowest, with 60% at 0.25 m-3·m-3) and no irrigation at 0.14 m-3·m-3. Quantum efficiency was similarly lower in 30% (0.60), compared to 0.72 and 0.69 for the 60% and unirrigated plots, respectively. Stomatal conductance was similar across all treatments. Stem water potentials were highest in plants receiving 30% (800 kPa), compared to 380 kPa in 60% and 360 kPa with no irrigation. Across all treatments, plant performance was correlated to soil water content, (ΦPSII P=0.03, r=0.24; gs P=0.05, r=0.22; kPa P=0.003, r=-0.33). Based on this study, Salvia guaranitica ‘Black and Blue’ should be irrigated at 60% of ET for best plant performance during summer heat and drought.

The growing demand for container ornamental plants opens new opportunities for nurseries to expand their business. However, expecting to improve plant quality, growers often overapply fertilizer and water. Excessive fertilizer application and overwatering can result in nutrient leaching and runoff. In addition, growers heavily rely on unsustainable sphagnum moss as a medium for growing their plants. Replacing sphagnum moss with coconut coir may increase production sustainability, and incorporating biochar may have potential to adsorb excess nutrients, thus lowering fertilizer concentration in leachate. In this study, we explored the suitability of using various mixtures of coconut coir and biochar for growing goldenrod, lavender, and chrysanthemum plants for two growing seasons. Results indicated that utilizing pine bark and coconut coir did not hinder plant growth and development compared to a traditional mixture of pine bark and sphagnum moss for any of the plants studied. Also, inclusion of 10% biochar did not enhance growth, nor did it reduce nitrate nitrogen and phosphorus concentration in container leachate. Biochar did not reduce nutrient leaching in this study. However, coconut coir was found to be a suitable substitute for sphagnum moss in container nursery production.

Light plays a crucial role in regulating various aspects of plant growth, development, and metabolism. The absorption spectra of photosynthetic pigments are primarily concentrated in the blue (400-500nm) and red (600-750nm) regions of light, making these wavelengths particularly influential in plant morphogenesis and photosynthesis. Varying the ratios of blue to red light can produce distinct morphological and physiological outcomes in plants. Blue light enhances photosynthetic activity and promotes more compact and robust growth, while red light encourages rapid growth and flowering. These specific combinations can be optimized for desirable traits in ornamental plants. This research aims to evaluate the effects of different combinations of blue and red light on the physiological and morphological characteristics of marigold (Tagetes erecta) ‘Crackerjack’. Seeds were sowed in Metromix 820 potting mix and placed on a misting bench for germination. After germination, seedlings were subjected to three different light spectra: 10% blue and 90% red LEDs (10¬B90R), 25%blue and 75% red LEDs (25B75R), and 50% blue and 50% red LEDs (50B50R) maintained using a spectrometer (StellarNet Inc.). A 90% shade cloth was used in each treatment to prevent the effect of outside light. The photosynthetic photon flux density (PPFD) was maintained at 150 µmol.m-2.s-1 and the photoperiod was maintained at 12 h light and 12 h dark. After four weeks, various physiological and morphological parameters were assessed in five destructively harvested seedlings per treatment. We found that seedlings grown under the 25B75R treatment exhibited greater height in comparison to those under the 50B50R spectrum but similar to seedlings under 10¬B90R. Stomatal conductance (gs) and photochemical efficiency (Fv/Fm) were higher under 50B50R than in 25B75R but comparable to those in 10¬B90R. Additionally, the SPAD and NDVI values, which indicate chlorophyll content and overall plant health, were highest under the 50B50R treatment. However, leaf area, total fresh weight, and total dry weight showed no significant differences among the treatments.

Deficit irrigation plays a crucial role in water conservation in urban landscapes. Calamagrostis ×acutiflora (feather reed grass) is an ornamental grass known for its neat clumps, golden plumes, and fast growth. It is gaining popularity in urban landscapes across arid and semi-arid regions in the United States. However, little is known about its responses to deficit irrigation. A field study was conducted in 2022 and 2023 at the Utah Agricultural Experiment Station’s Greenville Research Farm in North Logan, UT, to assess the effect of irrigation frequencies on the growth of feather reed grass. Reference evapotranspiration (ETo) data from a weather station in the Utah AgWeather System, Utah Climate Center, Logan, UT, was used to determine the irrigation frequency for each treatment. Four hundred plants were transplanted into the field plot, with twenty plants in each of the twenty 2 by 2-meter plots. Eighty plants within four plots were randomly assigned to one of five irrigation treatments, controlled based on 80%, 60%, 40%, 20%, and 0% ETo. Two harvests were conducted on 30 Sep 2022 and 3 Nov 2023, during which plant height, number of tillers, and biomass were recorded. Plants height, number of tillers, and biomass for both years exhibited a linear and quadratic increase as the irrigation frequencies increased from 0% to 80% ETo. In addition, the linear relationship between irrigation treatments and grass height became less distinct in 2023, although grasses irrigated at 80% ETo were taller compared with those at lower irrigation levels. Based on the results, an irrigation frequency of 40% to 60% ETo is recommended for feather reed grass to maintain optimal growth.

Water-efficient landscaping can reduce water consumption without compromising the aesthetical appearance of urban landscapes. Penstemon, with more than 250 species available in a spectrum of colors, is a popular choice in xeriscape designs and water-wise gardening due to its ability to thrive in dry conditions while providing attractive visual appeal. However, limited field trials have explored the responses of penstemon under deficit irrigation. This study, conducted at the Utah Agricultural Experiment Station’s Greenville Research Farm, North Logan, UT, USA, from 30 Jun to 31 Oct 2023, was to investigate the overall appearance and canopy temperature responses of three penstemon species: Penstemon barbatus (Cav.) Roth ‘Novapenblu’ (Rock CandyTM blue penstemon), Penstemon pinifolius (pineleaf beardtongue), and Penstemon strictus (rocky mountain beardtongue), under three irrigation frequencies. Reference evapotranspiration (ETo) was utilized to control irrigation frequencies. Eight plants of each penstemon species were randomly assigned to one of three deficit irrigation treatments, calculated based on 80% ETo (high), 50% ETo (moderate), and 20% ETo (low). A monthly evaluation of overall appearance was conducted. Top-view infrared images of plant canopies, from which canopy temperature can be calculated, were captured using a thermal camera. Results revealed that higher irrigation frequency led to better overall appearance, with some variability observed among species and months. Moreover, increased irrigation frequency correlated with lower canopy temperatures, displaying species-specific responses. Further observation is needed to compare the responses of P. strictus, P. pinifolius, and P. barbatus under field conditions.

Water scarcity is a pressing issue in Utah and the Intermountain West, leading to a growing interest in exploring alternative water sources for landscape irrigation. However, alternative water often contains elevated levels of salts, such as sodium chloride (NaCl), which can negatively impact plant growth and appearance. This study investigated the effect of saline solutions on the aesthetic value, growth, and stomatal conductance of three ornamental species: Hibiscus syriacus ‘JWNWOOD4’ (Pink Chiffon® rose of sharon), Viburnum carlesii ‘Spiro’ (koreanspice viburnum), and Vitex agnus-castus ‘SWVACSD’ (lilac chastetree). Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 0.9 dS·m-1 and saline solutions at 5.0 or 10.0 dS·m-1 for eight weeks. Visual quality was rated weekly using a reference scale ranging from 0 to 5 (0 = dead, 5 = excellent without foliar salt damage). Half of the plants per treatment per species were destructively harvested on 16 Aug (first harvest), and the remaining plants on 4 Sep (second harvest). Plant growth parameters and stomatal conductance were recorded at harvests. Foliar salt damage, such as leaf discoloration and necrosis, was prominently observed in plants, particularly in Viburnum carlesii subjected to elevated EC irrigation. Higher stomatal conductance was consistently observed in all plants irrigated with nutrient solution compared to those under saline irrigation. Interestingly, the salinity treatment did not significantly affect the growth of Vitex agnus-castus, indicating its high salt-tolerance. Notably, Viburnum carlesii displayed higher sensitivity to salinity stress compared to the other two ornamental species. These findings highlight significant variations in responses among the ornamental plant species under saline irrigation at varying EC levels, emphasizing the necessity of employing appropriate alternative water usage strategies.

BeeGardens Mobile Application Improves Pollinator Plant Knowledge Gain in Landscaping and Gardening Courses - Sandra Wilson
Pesticide Management Decisions Affect Contamination of Nectar in Containerized Ornamental Plant Production - Patrick Wilson
Comparing Pollinator Species Richness and Abundance Between Pycnanthemum Species and Accessions - Kaitlin Swiantek
The Art and Technique of Producing Unique Lagerstroemia Plants - Donglin Zhang
Effects of Different Pruning Regimes on Growth Reallocation and Carbon Storage in Buxus microphylla var. japonica ‘Winter Gem’ - Andrew Loyd
Establishment, Growth, and Physiology of Container-Grown Trees Following Root Remediation at Planting - Bert Cregg
The Effects of Mulch Color and Depth on Soil Temperature and Light Transmission - Damon Abdi
Subterranean Termite Landscape Mulch Consumption Challenge - Edward Bush

Florida is home to over 300 species of native wild bees, some in critical decline. To encourage gardeners to plant bee friendly species that support bee pollinators year-round, an online application called BeeGardens was built using a shared library of code and a relational database management system. The application, accessible by a mobile device or computer, enables users to quickly access over 85 bee-friendly plants that attract 12 primary bee groups; and provides tips for incorporating these into different landscape designs (https://ffl.ifas.ufl.edu/bees). The functionality and usefulness of the app was evaluated by students enrolled in two courses at the University of Florida: Florida Native Landscaping and Annual and Perennial Gardening, taught in different semesters. Before and after the semester, students were asked to report their abilities to 1) identify bee-friendly plants, 2) identify bee pollinators, and 3) design a bee-friendly garden, using a Likert scale with responses ranging from 1 (strongly disagree) to 5 (strongly agree). Means of pre- and post-test responses showed a significant perceived knowledge gain upon using the BeeGardens online application in both courses. This data was consistent with pre- and post-tested means where students were asked to identify three major pollinator plants and three major pollinators using multiple choice response options. Test scores increased by 26.3% and 37.9% in Annual and Perennial Gardening and Florida Native Landscaping, respectively. The majority of students (95.0%) agreed or strongly agreed this learning tool was organized, easy to navigate, and would use it in the future. Since its inception in March 2021, this web application has been accessed by over 26,554 new users from across Florida and beyond.

A forum for discussion of potential collaborations with regards to ornamentals – i.e. floriculture, nursery crops, breeding, turf, ornamentals industry, botanic gardens, landscape industry, orchids, etc.

Declines in pollinator populations have gained much attention over the last decade. Exposures to pesticides are one potential contributor to these declines. Given that the ornamental plant production industry produces crops that are attractive to pollinators and that pesticide use is often integral to ensuring plants are pest-free, attention is needed to assess and possibly reduce contamination of flower nectar and pollen before plants go to market. Three major factors associated with pesticide management practices that may influence contamination of floral resources are: application method, application rate, and application timing relative to flowering. Using the systemic insecticide thiamethoxam as a model pesticide and Salvia x ‘Indigo Spires’ (Salvia longispicata x S. farinacea) as a model species, this study investigated the influence of each of these factors on contamination of nectar. Plants were treated by spray and drench methods, at low and high rates according to the pesticide label, and before flower buds formed or close to the time of floret opening. Nectar samples were collected using microcapillary tubes when all plants were uniformly flowering and thiamethoxam concentrations were analyzed by LC-MS/MS. Concentrations of thiamethoxam in nectar were highest in drench applications, regardless of application timing and rate, and exceeded published LC50s for native bees and/or honeybees. Thiamethoxam concentrations were much lower in the spray-applied treatments, but they still exceeded published LC50s for native bees and/or honeybees except for the spray treatment applied before blooming at the low rate. These results provide insight into how some pesticide management practices influence contamination of floral resources and indicate a need for developing best management practices focused on limiting thiamethoxam exposures once plants go to market. Additional studies are underway to evaluate other plant species and systemic insecticides to address gaps in knowledge.

Pollinators play a crucial role in the ecosystem, human health, and the economy. However, despite the significance of pollinators, their populations are declining globally. Pycnanthemum is a marketable pollinator-attractive plant that could supplement pollinator resources in the landscape. Breeders would benefit from a comparison of the pollinator attractiveness between Pycnanthemum species and accessions. Cultivating Pycnanthemum should focus on aesthetic traits and maximizing pollinator abundance and species richness. Pollinator visitation was compared among three species and five accessions of Pycnanthemum (P. flexuosum (F), P. virginianum (V), and three accessions of P. tenuifolium (T1-T3)) using observations and capture. Lepidoptera, honey bees (Apis mellifera), Diptera, carpenter bees (Xylocopa spp.), small bees, and bumble bees (Bombus spp.) were observed most abundantly on Plant F. Plant V attracted the highest number of pollinators overall, with Apis mellifera (honey bees) accounting for more than half of the pollinator visitation. Xylocopa spp. (carpenter bees) and honey bees did not have a significant preference between the species. Plants F, T2, T3, and V attracted the greatest abundance of Diptera (flies). Wasps were most attracted to Plants T3 and V, while Bombus spp. (bumble bees) was observed most often on Plants F and V. Plant F attracted the highest number of Lepidoptera (butterflies and moths) and small bees. The species richness of pollinators did not significantly differ across Pycnanthemum species, with at least 24 to 29 different pollinator species visiting each plant. A range of factors, including olfactory cues, the morphology of plants, and accessibility of resources, may have affected pollinator preferences. Determining which Pycnanthemum species attracted an abundance and diversity of pollinators provides breeders a foundation for cultivation and conservation expectations.

Crape myrtle (Lagerstroemia L.) stands as a ubiquitous presence in landscapes worldwide. Beyond its captivating smooth and exfoliating bark, a spectrum of flower colors, and impressive variable mature heights, the artistic modeling potential of crape myrtle has found favor in the high-end landscape market. Crafting a crape myrtle tree becomes a gratifying and imaginative endeavor. The preeminent modeled shapes include vases, screenings, letters, columnar forms, dragon-inspired (animalistic), symbolic representations, pavilions, tunnels, tree bonsai, ornamental root architecture, and even cartoon characters. Constructing a foundational armature from steel demands your artistic prowess and creativity, serving as the structural basis for the tree. Opting for fast-growing crape myrtle cultivars with pliable branches becomes imperative for success. Consistent pruning becomes a requisite to mold the growth pattern according to our artistic aspirations. Utilizing modeling wire facilitates the creation of the trunk and branch framework, with strategically tied crossed knots enhancing natural grafting unions. Developing distinctive Lagerstroemia plants requires a more extended timeframe and demands advanced modeling and pruning techniques compared to conventional growth processes. This production journey provides ample creative freedom and the ultimate performance should align with our artistic vision and the preferences of our clientele. Future studies should delve into plant growth dynamics and the development of trunk/branch anatomical structures to further enhance our understanding of this artistic horticultural practice.

Hedge shaping and size maintenance is often accomplished with electric or gas-powered shears due to a lower cost compared to hand pruning. Shearing plants arbitrarily removes the apical growing points from external portions of the shrub to achieve a desired shape and size of the plant and often results in poor quality cuts, leaving ragged ends of woody tissues or leaves. Contrarily, hand pruning makes strategic, ‘clean’ cuts often back to lateral branches to achieve these goals. Use of plant growth regulators like paclobutrazol (PBZ) can reduce the frequency of pruning and could be a useful component of a hedge management program. The purpose of this study was to investigate the effects of shearing, hand pruning, and/or PBZ application on regrowth of foliage and non-structural carbohydrates (NSCs) of ‘Winter Gem’ boxwood over time. Fifteen shrubs each per pruning type x frequency combination were pruned with bypass hand pruners (hand pruned) or gas-powered shears (sheared) in 2021, 2022, and 2023 once or twice per growing season. In addition, another 15 shrubs each were sheared once followed by an immediate application of a foliar PBZ (i.e. Trimtect®) in accordance with the label using an electric backpack or left as non-pruned controls. In 2021 and 2022, shrubs were pruned by removing 15 percent of the overall height and 20% of the overall widths in two perpendicular directions of each shrub. In 2023, pruned shrubs were cut back to the previous season’s overall height and width. Regrowth was measured by weighing the fresh biomass removed at each pruning and NSCs were measured from ten woody twigs from the exterior of each shrub using the phenol-sulfuric acid quantification method. Two and three years after pruning, shearing shrubs twice had significantly more biomass produced year over year compared to hand pruning, while PBZ treated shrubs had the least amount of regrowth. NSCs trended to be highest in shrubs that were hand pruned once or in PBZ treated shrubs, while the least in shrubs that were sheared twice. PBZ-treated shrubs had tighter clusters of internodes resulting in approximately 30% reduction in stem elongation compared to controls. The differences in growth dynamics and carbon storage across these different pruning strategies can have different long- and short-term implications in managing boxwood hedges, which will be presented here.

Root defects, especially circling roots, are a major concern when planting container-grown trees. In this study, we compared survival, crown dieback, and plant water potential of four common landscape tree species (Carpinus caroliniana, Liriodendron tulipifera, Ostrya virginiana, and Platanus × acerifolia) in response to root modifications (control, bare-root washing, shaving, and vertical slicing) prior to planting. P. × acerifolia trees were robust with respect to root correction treatments and had 100% survival except for some mortality following vertical root-ball slicing. In contrast, C. caroliniana, L. tulipifera, and O. virginiana trees had significant mortality and crown dieback in response to bare-root washing. The responses of these species to bare-root washing reflected extreme plant moisture stress immediately after planting. These three species are also considered ‘difficult to transplant’ as bare-root nursery stock. Our results suggest that trees that are generally known to be difficult to transplant as bare-root stock are poor candidates for extreme root disturbance such as bare-rooting when grown as container trees. In contrast, shaving and vertical slicing had little or no adverse effects on tree survival, crown dieback, or plant water potential.

Mulching is a common task in the landscape industry, with materials selected to provide environmental benefits (i.e. moderating soil conditions, limiting weed growth) and aesthetic value, with colored mulches often employed to add an artistic element to landscapes. Questions arise over possible effects that mulch color may have on soil temperatures, especially when using darker materials. This research investigated the effects of a commercially available shredded mulch (dyed black, brown, or red) on soil temperature and light transmission in model research plots. A plot at the Hammond Research Station was cleared, graded, and prepared with a typical bed mix comprised of pine bark and sand. A total of 21 sub-plots were prepared, where each sub-plot had a remote temperature sensor buried at the base of the bed mix (8 cm below surface), and a temperature and light sensor placed over top of the bed mix. Mulch was applied to depths of 5 cm or 10 cm directly over the top of the temperature and light sensors, with n=3 for our control (no mulch over the bed mix), red mulch (n=3 for depth of 5 cm and n=3 for depth of 10 cm), brown mulch (n=3 for depth of 5 cm and n=3 for depth of 10 cm), and black mulch (n=3 for depth of 5 cm and n=3 for depth of 10 cm). Soil temperature conditions (both within the mulch itself, and at the base of the bed mix) as well as light transmission through the mulch layer was recorded every 30 minutes throughout a spring and summer season at the Hammond Research Station. Blank (unmulched) plots naturally experienced the most light transmission and temperature extremes. Regardless of mulch color or depth, light transmission was substantially reduced (and often eliminated) equivalently between mulch treatments. Temperature was measured both within the surface mulch layer, and 8 cm below into the subsurface bedding mix. While subsurface temperatures were effectively equivalent between all mulched plots, surface temperatures exhibited substantial differences between mulch colors and depths. Thinner mulch layers experienced more extreme surface temperature fluctuations, with mulch color influencing peak temperatures. The results of this work suggest that different mulch colors and depths have a greater influence on temperature at the immediate surface, but far more muted differences in subsurface temperatures.

Formosan Sub-terranean Termite Landscape Mulch Consumption Payton Floyed1, Edward Bush*2, and Qian Sun1 (1)LSU Department of Entomology and (2)LSU AgCenter, SPESS, Baton Rouge, LA Many landscapers utilize organic mulch substrates composed primarily of wood and bark, making it an ideal food source for the Formosan subterranean termite (Coptotermes formosanus). Formosan termites are one of the most destructive structural pests and recognized as one of the 100 worst invasive species in the world. While foraging, these termites can find and may be able to fully establish colonies in landscaping that uses mulch. The mulch type that attracts the most termites has not been widely investigated and continues to be an issue that needs to be determined. The objective of this research was to measure the biomass consumption by termites. Three C. formosanus colonies were used, two from New Orleans, Louisiana, and one from Gonzales, Louisiana. All were maintained in the laboratory using three total replications per experiment over a 14 d period. Five-hundred total termites (450 workers and 50 soldiers) were placed in each arena (7.5”x10”x4” plastic bin) which used a sand layered bottom for both worker and soldier termites. Each arena was covered with a dark plastic bag to mimic typical subterranean foraging conditions. Mulch particle size distribution and bulk density resulted in expected differences with crushed pine straw having the finest particle size (>50% particle size

This workshop is to introduce the coordinated network of non-biased plant trials that has been successfully established to assess plant growth and aesthetic quality under deficit irrigation in six locations with different climate and soil types. The standard evaluation method will be highlighted to allow the audience to gain a behind-the-scenes look at the success and challenges of managing a multi-year and multi-state field project titled ‘Climate Ready Landscape Plants’. The evaluation methods employed in this project could potentially be utilized for selecting climate-resilient plants in other regions of the United States and beyond.

During their presentations, participants will be invited to: 1) Learn about the process of building cooperator and stakeholder engagement for a regional multistate project. 2) Practice using an Excel-based Irrigation Log to apply deficit irrigation using reference evapotranspiration published by local weather stations. 3) Practice evaluating selected landscape plants (pictures and/or live plants purchased from Home Depot in Honolulu) using the Rubric for Plant Aesthetic Ratings developed by the UC Landscape Plant Irrigation Trials™ team. 4) Learn the standard methods for collecting plant physiology data of selected landscape plants across multiple locations and understand the project results regarding stomatal conductance, which was collected using LI-600 Porometer/Fluorometer, LI-6800 Photosynthesis System, and/or CIRAS-3/4 Portable Photosynthesis System, METER Groups, etc. Ventors such as LI-COR Biosciences, PP Systems and/or METER Group will be invited to demonstrate their equipment for plant physiological measurements (e.g. stomatal conductance) during the session. 5) Learn the standard methods for collecting plant growth and visual quality data across six locations and understand the challenges and results of common taxa tested in six diverse geographic locations. 6) Learn step-by-step how to conduct open houses and invite professionals to help evaluate plants in the field trials, as well as how to collect and use the data.

Following their presentations, the six speakers along with other team members including Dr. Alessandro Ossola, Dr. Lloyd Nackley, Dr. Ryan Contreras, Dr. Shital Poudyal, and Dr. Youping Sun, will be invited to join a 30-min panel discussion session to further share the success and challenges of managing a multi-year and multi-state field project. They will delve into the opportunities and challenges currently facing the Green Industry. This discussion aims to foster future collaboration for expanding current research and Extension efforts. The goal is to promote the production and utilization of low-water-use plants within the green industry and among the gardening public, especially in the context of a changing climate.

Western U.S. nursery stock, bedding, annual, and perennial plant sales exceeded $2.9 billion in 2017, with nursery stock sales from this region alone accounting for 37.6% of total U.S. sales (Agricultural Statistics, 2017). However, climate change and increased urban water demand threaten the future of the Green Industry. The Western U.S. is expected to endure extreme droughts escalating in severity due to climate change, less predictable precipitation patterns, and decreased soil moisture (Cayan et al., 2010). Urban water supplies will be further stressed by population growth. The populations of Arizona, Idaho, Nevada, and Utah increased by 1.7% or more from 2017 to 2018 (United States Census Bureau, 2018). To address these challenges, growers must supply low-water-use plants and the landscape industry must utilize them to facilitate water conservation by reducing landscape irrigation requirements. In response to this need, the USDA Agricultural Marketing Service Specialty Crop Multi-State Program funded a project titled ‘Climate Ready Landscape Plants’ in 2020 to the University of California, Davis. With the funding, trial methods developed in California have been expanded to four additional western states: Arizona, Oregon, Utah, and Washington. A coordinated network of non-biased plant trials has been established to assess plant growth and aesthetic quality under three irrigation frequencies. Low-water-use plants were identified in 2022 and 2023 and will be recommended for production and utilization. The information developed will be provided to the green industry to aid in sustainable decision-making, marketing, and business support. The evaluation methods employed in this project could potentially be utilized for selecting climate-resilient plants in other regions of the United States and beyond. Agricultural Statistics 2017. 2017. United States Department of Agriculture National Agricultural Statistics Service. https://www.nass.usda.gov/Publications/Ag_Statistics/2017/Complete%20Ag%20Stats%202017.pdf Cayan, D.R., Das, T., Pierce, D.W., Barnett, T.P., Tyree, M., and Gershunov, A. 2010. Future dryness in the southwest US and the hydrology of the early 21st century drought. Proceedings of the Natl. Acad. of Sci. 107 (50), 21271-21276. https://doi.org/10.1073/pnas.0912391107 United States Census Bureau. 2018. Nevada and Idaho are the nation’s fastest growing states. United States Department of Commerce. https://www.census.gov/newsroom/press-releases/2018/estimates-national-state.html

Coordinator(s)

• Youping Sun, Utah State University, Department of Plants, Soils & Climate, Logan, Utah, United States

Moderator(s)

• Lloyd Nackley, Oregon State University, Horticulture, Aurora, OR, United States

Speaker/Participant(s)

• Lorence Oki, Building Cooperator and Stakeholder Engagement for a Regional Multistate Project 
• Jared Sisneroz, Coordinating a Standard Irrigation Protocol across Six Diverse Plant Trial Locations 
• Karrie Reid, Introducing the Criteria for Plant Aesthetic Ratings
• Natalie Levy, A Step-by-Step Guide for Organizing a Successful Open House Event
• Soo-Hyung Kim, Coordinated Assessment of Physiological and Morphological Traits of Landscape Plants across Multiple Locations in the Western United States
• Ursula Schuch, Performance of Landscape Shrubs under Three Irrigation Regimes in Arizona

The Climate Ready Landscape Plants Project. Testing Plants For Drought Tolerance Across The Western U.S. - Lorence Oki
Performance of landscape shrubs under three irrigation levels in Arizona - Ursula Schuch
Performance of Landscape Plants in California’s Central Valley Under Three Levels of Deficit Irrigation - Jared Sisneroz
Field Trials of Landscape Plants under Reduced Irrigation Frequency - Zirui Wang
Understanding Hernando County Residents' Perspectives on Fertilizer Use and Regulations - William Lester
Using Different Ratios of Blue and Red Light to Induce Drought Tolerance Morphology in Zinnia - Anju Chaudhary
Techniques to Improve Growth, Heat, and Drought Tolerance in Container Grown Trees - Drew Zwart
Using Marketing Initiatives to Promote the UF/IFAS Extension Florida-Friendly Landscaping Program - Tom Wichman

The Climate Ready Landscape Plants project evaluates the performance of plants exposed to three different deficit irrigation treatments in six climate zones. The experimental fields are completely replicated at all of the sites with plants spaced in a 2m x 2m layout, 8 replicates per treatment, up to 15 taxa tested per site, and irrigation based on reference evapotranspiration (ETo) with treatments of 20%, 50%, and 80% of ETo. Irrigation applications consist of a fixed volume of water depending on soil plant available water as determined by the US Geological Survey maps accessed via SoilWeb. The interval between irrigations was determined by accumulating daily ETo modified by the treatment factor. Irrigation occurred when the trigger value was attained. Plants were installed in the fall and irrigated with sufficient water for establishment during the first irrigation season and treatments were imposed during the second irrigation season. Monthly during treatment, 6 qualitative assessments of each plant were conducted and measurements in three directions were recorded to calculate a Plant Growth Index until the end of the treatment period that typically concluded in October. A substantial effort was made to ensure site-to-site consistency of the qualitative assessments by developing a ratings rubric and conducting frequent site visits with project management to “calibrate” site staff conducting the evaluations. Open House Field Days were conducted during the treatment season to which horticultural professionals and Master Gardeners were invited to evaluate the plants. This provided additional data and introduced the plants to potential users. This project started in 2004 as a graduate student research project, was expanded periodically at UC Davis, and then duplicated in 2017 at the UC South Coast Research and Extension Center in Irvine, CA as the University of California Landscape Plants Irrigation Trials™ (UCLPIT) project. With an award from the USDA Specialty Crops Multistate Program in 2019, the project was expanded to the University of Washington, Oregon State University, Utah State University, and the University of Arizona which facilitates the comparison of plant performance in response to deficit irrigation treatments across the western region of the U.S. The data collected leads to recommendations for irrigating those plants that are used by homeowners and landscape irrigation managers and assists landscape designers and architects designing landscapes that are water conserving and complying with California's landscape water conservation regulation, the Model Water Efficient Landscape Ordinance (MWELO).

Fifteen taxa of shrubs growing in a field in Tucson, Arizona were irrigated with three levels of irrigation based on local reference evapotranspiration (ETo) to assess growth and plant quality. Plants established during 2021 under 80% of ETo and in 2022 were irrigated at 20%, 50% or 80% of ETo. Irrigation was applied 2, 9, and 15 times between April 1 and October 31, 2022 for the low, medium, and high irrigation, respectively. Best performing plants were Asclepias linaria ‘Monarch Magnet’, Dodonaea viscosa ‘Emerald Ice’, Eremophila glabra ssp. carnosa ‘Winter Blaze’, Ericameria laricifolia ‘Aguirre’, Hamelia patens ‘Sierra Red’, Leucophyllum frutescens ‘San Antonio Rose’, Leucophyllum langmaniae ‘Rio Bravo’, Tecoma ‘Red Hot’ and Rosmarinus officinalis 'Arp'. Irrigation did not affect plant growth of these nine taxa from April to October. Monthly visual quality assessment of some taxa was temporarily affected by irrigation, however, all performed acceptable or better at the low irrigation with the exception of Asclepias linaria ‘Monarch Magnet’ which had less than acceptable ratings in July and August for the low and high irrigation treatments. This taxa also had 62% mortality of plants under the high irrigation treatment between July and October. Hamelia patens ‘Sierra Red’ plants had frozen to the ground in winter 2022 and started to regrow in May. Five of the taxa (Dodonaea viscosa ‘Emerald Ice’, Eremophila glabra ssp. carnosa Winter Blaze, Ericameria laricifolia Aguirre, Hamelia patens Sierra Red, and Leucophyllum frutescens ‘San Antonio Rose’) maintained a high overall rating at the lowest irrigation treatment. Two field days were held in August and October 2022 where participants from the green industry and related sectors were invited to rate overall appearance, flowering and foliage of one representative plant from each taxa and irrigation treatment. Ratings from field day participants were similar to those from researchers during that month. Most participants’ favorite plants included the five taxa with consistently high overall ratings, only Dodonaea ‘Emerald Ice’ was among the top four favorites at both field days. All nine taxa tested are low water use shrubs that can grow in the landscape with 20% of ETo in the low desert in Arizona. However, some may benefit from additional irrigation during the hottest time of the year for optimum performance.

To develop landscape irrigation recommendations, 22 taxa of landscape plants were evaluated under three levels of deficit irrigation in a field trial. The taxa consisted of common horticultural perennials and shrubs including multiple cultivars of Hibiscus syriacus, Nandina domestica, Rosa spp., and Salvia spp. Based on anticipated plant size and cultural requirements, taxa were planted in one of three adjoining fields, with each field laid out in a grid pattern with either 2 or 3 meter spacing between rows and between individual plants in each row. All fields were covered with a 2-3” layer of chipped bark mulch. For each taxon, 24 individuals were planted with eight replicates per irrigation treatment in a randomized complete block layout with both taxa and irrigation treatment being randomly assigned. Plants were installed in March as bareroot inputs, with containerized plants installed from April to early June of 2021. Daily reference evapotranspiration (ETo) values from a local weather station were obtained from the California Irrigation Management Information System. The amount of plant available water (PAW) for the trial site was obtained from the US Geological Survey via the Soilweb application. In 2021, plants were irrigated regularly to fully establish their root systems. From April to October 2022, plants were irrigated with one of three deficit irrigation treatments equal to 80%, 50%, or 20% of ETo. The treatments functioned similarly to a crop coefficient to modify daily ETo values. The modified ETo values were used to estimate when 50% of PAW was depleted for each treatment. Irrigations occurred whenever this threshold was reached, with the volume of water applied being equal to 50% of PAW. The volume applied at each irrigation was constant across treatments with the frequency between irrigations varying by treatment. As a result, the 80% treatment was irrigated most frequently with the 20% treatment was irrigated thrice during the deficit period. Monthly during the deficit period, each plant was rated on six categories of aesthetic quality and length, width, and height measurements were collected to develop a plant growth index. Aesthetic performance between the treatments was compared using an ANOVA in conjunction with Tukey’s HSD post-hoc test in R. A majority of the taxa evaluated maintained acceptable aesthetic quality ratings on the lowest irrigation treatment. Two taxa evaluated, Lagerstroemia ‘SMNLCIBF’ Center Stage® Red and Rosa ‘ChewPatout’ Oso Easy® Urban Legend achieved high levels of aesthetic performance on the 20% treatment.

Utah has experienced significant drought conditions, with 99.3% of the land under drought stress from the previous year to the present. In response to this challenge, deficit irrigation landscapes are gaining popularity in arid regions. This study aimed to investigate the overall appearance, plant growth, and physiological response of ten ornamental plants to deficit irrigation. The selected species include Caryopteris ×clandonensis ‘Blauer Splatz’ (Sapphire SurfTM bluebeard), Cercis canadensis (eastern redbud), Cercis occidentalis (western redbud), Cotoneaster ×suesicus ‘OSUCOT2’ (Emerald BeautyTM cotoneaster), Hesperaloe parviflora ‘Straight Up Red’ (‘Straight Up Red’ texas red yucca), Miscanthus sinensis ‘NCMS2B’ (bandwidth maiden grass), Physocarpus opulifolius ‘Diabolo’ (Diabolo® ninebark), Physocarpus opulifolius ‘Little Devil’ (Little DevilTM ninebark), Rosa ×hybrida ‘Meifranjin’ (Blushing Drift® rose), and Vitex agnus-castus ×rotundifolia ‘Helen Froehlich’ (Summertime BluesTM chaste tree). Eight plants per species were randomly assigned to one of three deficit irrigation frequencies, calculated based on 80% reference evapotranspiration (ETo) (high), 50% ETo (medium), and 20% ETo (low) at the Utah Agriculture Experiment Station’s Greenville Research Farm, North Logan, UT, USA. The overall appearance was evaluated biweekly, spanning from 30 Jun to 31 Oct 2023. Plant growth and stomatal conductance were recorded monthly during the growing season. The growth of plants was not significantly affected by reduced irrigation frequency. However, the impact of deficit irrigation on aesthetic performance and stomatal conductance was notable, particularly during August and September. The results highlight variability in plant performance across species, with Caryopteris ×clandonensis and Cotoneaster ×suesicus showing consistent performance across irrigation levels. However, Cercis canadensis and Physocarpus opulifolius ‘Diabolo’ exhibited a more pronounced difference under varying irrigation levels. Funding Source USDA Agricultural Marketing Service Specialty Crop Multi-State Program, USDA NIFA Hatch project UTA01666, 2022 Extension Water Initiative Grants Program, Utah State University’s Center for Water-Efficient Landscaping, and the Utah Agricultural Experiment Station

In response to recent revisions to the fertilizer ordinance in Hernando County, our research endeavors to delve into the attitudes and behaviors of residents towards fertilizer usage. With over 100 counties and municipalities in Florida implementing urban landscape fertilizer ordinances, Hernando County serves as a significant case study in understanding the dynamics of public perception and compliance. Our project employs a multi-faceted approach to gather comprehensive insights into resident perspectives. Tailored surveys have been developed to assess various aspects, including residents' knowledge of lawn care, familiarity with the county's fertilizer ordinances, current landscape conditions, and practices regarding fertilizer application. These surveys are being disseminated through diverse channels, encompassing social media platforms, the Hernando Extension networks, and Hernando County Utilities Department customers. Additionally, forthcoming focus group interviews will provide qualitative insights, offering a deeper understanding of community sentiments and the underlying factors shaping attitudes and behaviors. Through the integration of quantitative and qualitative data analysis, our aim is to gain a holistic understanding of the landscape of fertilizer usage in Hernando County. This entails not only identifying prevalent practices but also discerning the concerns and barriers faced by residents in adhering to the fertilizer ordinances. Such insights are pivotal in informing the development of targeted educational materials aimed at addressing community concerns, dispelling misconceptions, and providing practical guidance on responsible fertilizer usage. Our initial online survey revealed that 31% considered themselves very familiar with the Hernando County Fertilizer Ordinance, but 31% were not familiar with the details at all (n=383). Of these respondents, 73% care for their lawn and landscape themselves, with 11% using a professional service. Most residents responded that their lawn was fertilized at least once per year, with 18% saying that their lawn was never fertilized (n=844). Ultimately, the findings of our research hold significance beyond Hernando County, offering valuable lessons and strategies for promoting sustainable landscape management practices in similar contexts across Florida and potentially beyond. By fostering greater awareness, understanding, and knowledge of proper fertilizing practices, our project contributes to the broader goal of safeguarding water quality and environmental integrity for present and future generations.

Growing population, rapid urbanization and economic expansion have been raising the demand for fresh water. Additionally, climate changes, characterized by warmer temperatures, shifting precipitation patterns, and reduced snowpack are diminishing the water availability presenting new challenges for agricultural water use and conservation, particularly in the arid western states. One approach to addressing water scarcity involves inducing drought tolerance in crops. Plants exhibit physiological, morphological, and biochemical changes upon exposure to different wavelengths of light. This study focuses on determining the optimal ratio of blue to red light for inducing drought tolerance morphology in Zinnia elegans ‘Envy’. Seeds were sowed in Metro-Mix® 820 (SunGro Horticulture, Agawam, MA, USA) and kept on a misting bench. After germination, the plugs were exposed to full spectrum LED grow lights (ScynceLED, Mesa, Arizona) maintained at three ratios of blue and red light, 10:90, 25:75, and 50:50, controlled using a spectrometer (StellarNet Inc., Tampa, Florida, USA) in a covered chamber. The Photosynthetic photon flux density (PPFD) was maintained at 150 µmol.m-2.s-1 and the photoperiod was maintained at 12 hour dark and 12 hour light period. After four weeks of treatment, physiological and morphological parameters were measured in five destructively harvested plugs per treatment. The leaf number, growth index, and leaf area index showed no significant differences among treatments, however, the rate of assimilation and stomatal conductance were found highest under the 50:50 blue and red light ratio, compared to 25:75 but similar to 10:90. The total dry weight, leaf thickness, SPAD, and NDVI values were also higher at the 50:50 ratio, with total dry weight comparable to the 25:75 ratio. Subsequent irrigation treatments at 25% and 35% volumetric water content (VWC) were applied with the help of automated irrigation system using capacitance sensor, ECH2O 10HS (Meter Group, Pullman, WA, USA) to assess water requirements under different ratios of blue and red light suggesting a potential of these light treatments to reduce the Zinnia’s water needs.

Heat and moisture stress are increasing limitations to production of container-grown trees and growth of landscape trees, while reducing water use is an increasingly common goal. In two experiments, we investigated methods for reducing stress caused by limited water and extreme heat in container-grown tree seedlings in Aurora, Oregon. In the first experiment, we evaluated the potential for several ‘biostimulant’ or stress-tolerance inducing, soil-applied materials to improve growth of tree seedlings (Betula nigra) under limited water conditions. In the second experiment, we evaluated one of the most promising materials from that study in comparison to several other known or potential stress-reducing materials or techniques. In the first study, B. nigra seedlings were grown in pots with full water (determined by site evapotranspiration rate), one-half water, or one-half water with four different commercially available ‘biostimulant’ products that are marketed as inducing tolerance to moisture and heat stress in plants. Caliper growth, visual rating, and chlorophyll fluorescence values all showed that in the low-water groups, the plants treated with a mannitol plus calcium chelate product or a potassium phosphite product performed best and significantly better than the low-water control group. In the second experiment, over the course of two seasons we compared the effects of soil-applied potassium phosphite with other methods previously shown to reduce heat and/or drought stress. Abnormal extreme heat events, or ‘heat domes’, occurred during both growing seasons. Container-grown red maple (Acer rubrum) saplings were grown with moderate water and subjected to one of six treatments: untreated control, fresh-water misters triggered by preset ET value, kaolin foliar treatment, potassium phosphite soil application, propiconazole foliar treatment, and paclobutrazol foliar treatment. After two growing seasons, the mist treatment significantly improved growth compared to control plants while the potassium phosphite and kaolin treatments showed non-significant trends of improved growth. Based on these two studies, it is concluded that where possible, mist treatments during hot and dry conditions can improve container-grown tree seedling growth and condition, while potassium phosphite soil treatment and kaolin foliar treatments are likely to improve growth and condition in landscapes or where installation of misting apparatus is not feasible.

The UF/IFAS Florida-Friendly LandscapingTM (FFL) Program is Florida's premier Extension program for ecologically sustainable, science-based landscape practices that conserve water, protect water quality, and promote biodiversity. Since 1993, the FFL program has promoted water resource protection through both water conservation (water savings) and reducing non-point source pollutants (fertilizer nitrogen and phosphorus; pesticides) that may otherwise be carried into the state’s water bodies via runoff and/or leaching into groundwater. Despite longstanding promotion of FFL through Florida’s 67 county Extension offices, most Florida residents remain unaware of the program and its benefits. To promote public awareness of FFL, the program has undertaken a variety of marketing initiatives involving radio, television, social media, webinars, and online educational opportunities. On the radio, FFL produced a series of one-minute-long spots providing sustainable gardening tips. Called Florida-Friendly Landscaping in a Minute, the episodes aired twice each weekday on two NPR stations covering 19 northeast Florida counties. The daily listening audience was estimated at 4,600 for each airing, with 2.4 million total listeners each year. Webpage links to additional information back-up each episode. A wider audience was reached through the subsequent production of the Flip My Florida Yard television series. Produced in partnership with Crawford Entertainment with funding from the Florida Department of Environmental Protection, each 30-minute episode chronicles the complete makeover, or flip, of a homeowner’s typical Florida landscape into a more sustainable Florida-friendly landscape. All accomplished in eight hours, each episode features local designers and contractors and the local Extension agent, as well as a Maintenance Moment tip and a Yard Science segment featuring experts from UF/IFAS and other state entities. New shows air statewide on PBS and past episodes are streamed online. The program received a regional Emmy award in 2023. Flip My Florida Yard has been viewed more than 9.9 million times in the past year. FFL also recently hired a social media manager to increase FFL’s visibility on Facebook, Pinterest, Instagram, YouTube, and Linked-In. FFL’s social media reach is now growing exponentially. FFL also offers monthly webinars for both commercial and homeowner audiences. These webinars are archived to the FFL website and have accounted for more than 38,000 live and recorded views in the past year. Finally, the program has developed numerous online trainings and certification programs to help reach audiences at their convenience. As FFL begins its 32nd year, these marketing initiatives are helping it grow and reach new audiences.

The overall goal of this session is to highlight the latest advancements from the USDA Agricultural Marketing Service Specialty Crop Multi-State Program funded project titled “Climate Ready Landscape Plants”.

Coordinator/Moderator

• Youping Sun, Utah State University, Department of Plants, Soils & Climate, Logan, Utah, United States

Speaker/Participant(s)

• Jared Sisneroz, UC Davis
  Climate Ready Landscape Plants Trialed in Davis, CA
  Summary: To develop landscape irrigation recommendations, a field trial evaluated 22 taxa of landscape plants under three levels of deficit irrigation. Taxa included cultivars of Hibiscus syriacus, Nandina domestica, Rosa spp., and Salvia spp., among other common perennials and shrubs. Taxa were planted in a grid pattern with 2 meters spacing between rows and plants. Several larger taxa were planted in an adjacent field with 3 meters spacing. After an initial growing season of regular irrigation to establish the plants, from April to October 2022, plants were irrigated with one of three deficit irrigation treatments equal to 80%, 50%, or 20% of ETo. Treatments functioned like a crop coefficient in modifying daily ETo values. Irrigations occurred whenever this threshold was reached, with the volume of water applied being equal to 50% of PAW. The volume applied at each irrigation was constant across treatments with the frequency between irrigations varying by treatment. As a result, the 80% treatment was irrigated most frequently with the 20% treatment was irrigated thrice during the deficit period. Monthly during the deficit period, each plant was rated on six categories of aesthetic quality. Aesthetic performance between the treatments was compared using an ANOVA in conjunction with Tukey’s HSD post-hoc test in R. A majority of the taxa evaluated maintained acceptable aesthetic quality ratings on the lowest irrigation treatment. Two taxa evaluated, Lagerstroemia ‘SMNLCIBF’ Center Stage® Red and Rosa ‘ChewPatout’ Oso Easy® Urban Legend achieved high levels of aesthetic performance on the 20% treatment.
• Amelia Keyser-Gibson and Soo-Hyung Kim, University of Washington, United States
  Variation in Landscape Plant Aesthetics, Growth, and Physiology to Deficit Irrigation Across the Western U.S. (20 mins)
  Summary: Climate change is causing more frequent and severe droughts in the Western U.S., while concurrently, about 70% of urban water use is dedicated to landscape irrigation. Therefore, water conservation techniques in the horticultural space, such as planting water-use-efficient landscape plants, will be essential to reduce irrigation consumption. Five different taxa, Hibiscus syriacus ‘Gandini Santiago’ Purple Pillar®, Hibiscus syriacus 'ORSTHIB5x1' PPAF, Rosa ‘Meibenbino’ Petite Knock Out®, Rosa ‘ChewPatout’ Oso Easy® Urban Legend®, and Vitex ‘SMVACBD’ Blue Diddley®, were subjected to one of three water deficit treatments in six sites: Tucson, Arizona; Davis, California; Irvine, California; Aurora, Oregon; Logan, Utah; and Seattle, Washington. Plants were rated on foliage quality, flowering, pest tolerance, disease resistance, vigor, and overall appearance. Growth measurements were also taken to calculate a plant growth index and relative plant growth index. Stomatal conductance and the efficiency of Photosystem II (ΦPSII) were measured when the treatments were in full effect and compared to the aesthetic ratings to get a broad picture of plant health. Overall, at individual sites, treatment did have a significant effect on aesthetic qualities and growth of specific taxa. Additionally, between sites, aesthetic qualities and growth differed significantly. Stomatal conductance and ΦPSII were not higher in the high treatment for all taxa and differed significantly between most sites. Additionally, higher gs and ΦPSII did not correlate with higher aesthetic ratings and growth. Our results highlight the importance of climate-specific plant selection for reducing landscape water use while achieving satisfactory aesthetic qualities and growth of landscape plants.
• Ursula Schuch, University of Arizona
  Climate Ready Landscape Plants Trialed in Tucson, AR
  Summary: : Fifteen taxa of shrubs growing in a field in Tucson, Arizona were irrigated with three levels of irrigation based on local reference evapotranspiration (ETo) to assess growth and plant quality. Plants established during 2021 under 80% of ETo and in 2022 were irrigated at 20%, 50%, or 80% of ETo. Irrigation was applied 2, 9, and 15 times between April 1 and October 31, 2022, for the low, medium, and high irrigation, respectively. Best performing plants were Dodonaea viscosa ‘Emerald Ice’, Eremophila glabra ssp. carnosa ‘Winter Blaze’, Ericameria laricifolia ‘Aguirre’, Hamelia patens ‘Sierra Red’, Leucophyllum frutescens ‘San Antonio Rose’, and Tecoma ‘Red Hot’ which maintained a high overall rating at the low irrigation treatment. Irrigation did not affect plant growth of these taxa from April to October. Monthly visual quality assessment of some taxa was temporarily affected by irrigation, however, all performed acceptably or better at the low irrigation. Two field days were held in August and October 2022 where green industry professionals were invited to rate plant performance of one representative plant from each taxon and irrigation treatment. Most participants’ favorite plants included the taxa with consistently high overall ratings. The best performing taxa are low water use shrubs that can grow in the landscape with 20% of ETo in the low desert in Arizona. However, some may benefit from additional irrigation during the hottest time of the year for optimum performance.
• Natalie Levy, South Coast Research & Extension Center, The University of California Agriculture and Natural Resources
  Climate Ready Landscape Plants Trialed in Irvine, CA
  Summary: As climate extremes, population growth, and agricultural/industrial water demands continue to increase, urban landscapes are an essential area where water conservation efforts must be improved. Deficit irrigation trials of ornamental plants began at the University of California, Davis (UCD) in 2004 and became the University of California Landscape Plant Irrigation Trials (UCLPIT™). In 2016, it was replicated at UC Agriculture and Natural Resources’ South Coast Research and Extension Center (SCREC) in Irvine, California. Researchers observed differences in performance between sites on selected taxa indicating that plant species will have irrigation requirements that vary in different climates. In 2019, the UCLPIT methodology was expanded to multiple western climate zones and soil types in Arizona, Utah, Oregon, and Washington through a USDA Specialty Crops Multi-State Program grant. Two seasons of data were collected in 2022 and 2023. The overall appearance and plant growth of 12 shared ornamental plants to deficit irrigation were investigated. Eight plants per species were randomly assigned to 1 of 3 deficit irrigation frequencies, calculated based on 80% reference evapotranspiration (ETo) (high), 50% ETo (moderate), and 20% ETo (low). Overall appearance and plant growth were evaluated monthly during April to October in both 2022 and 2023 at SCREC. There were variations in overall appearance across species under deficit irrigation in both years of the trial. Evapotranspiration rates were higher in 2022 and more irrigation events occurred for all treatments. The Philadelphus madrensis ‘ORSTPHILx2’ (Swan Lake® mock orange) and the Philadelphus lewisii 'Blizzard' (Blizzard mock orange) species evaluated in 2022 had significantly greater overall appearance on the moderate treatment than the low treatment.

As Artificial Intelligence (AI) continues development at a rapid pace, our current teaching and learning methods are also swiftly transforming. AI itself is often combined with various technologies such as image recognition, virtual reality (VR), machine learning, adaptive learning algorithms, and gamification. With the merger of existing technology, AI and education will change the way we teach as well as how students learn. Some examples for teaching Horticulture, Landscape Architecture or Plant Science include individualized teaching, deep learning, adaptive learning environments, AI-based assessment and image recognition. In this Professional Interest Group Session speakers will provide examples of how they are using AI in their teaching methods, followed by an open discussion with the audience that should provide additional examples and applications.

Coordinator(s)

• Kathryn Orvis, Purdue Univ, Horticulture and Landscape Architecture, West Lafayette, Indiana, United States

Speaker/Participant(s)

• Mary Rogers, University of Minnesota, Department of Horticultural Science, St Paul, Minnesota, United States
  How to Incorporate Generative AI in Teaching a Writing Intensive Urban Agriculture Course (15 mins)
  Summary:
• Aaron Thompson, Purdue University, Horticulture and Landscape Architecture, West Lafayette, IN, United States
  Teaching with AI in Landscape Architecture (15 mins)
  Summary:
• Cynthia Haynes, Iowa State University, Horticulture, Ames, Iowa, United States
  Potential benefits and pitfalls of using AI software in Horticulture teaching. (15 mins)
  Summary:

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

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.

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

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

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.

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.

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.

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.

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.