ASHS 2024 Conference

Exploring the Effects of Irrigation Water Salinity on Physiology and Growth of Papaya (Carica papaya) in a Calcareous Soil - Ana Vargas
Physiological, Biochemical, and Morphological Responses of Achachairu (Garcinia humilis) to Soil Salinity, Flooding, and Exogenous Applications of 24-epibrassinolide - Federico Sanchez
Plant Physiological and Root Anatomical Responses of Two Novel Olive Cultivars (‘Oliana’ and ‘Lecciana’) Under Salinity - Khalid Hussain
Continuous monitoring of tree water status using microtensiometers for irrigation management in olive - Paula Guzman-Delgado
The Carbon Cost of Phosphorus Deficiency in Southern Highbush Blueberry - Marlon Retana-Cordero
Intra- and Inter-Annual Changes in Soil Health with Native Plant Monocultures - Bret Lang

In many tropical fruit production areas, including southern Florida, a rise in ocean levels resulting from climate change is anticipated to lead to greater inland intrusion of saltwater, thereby increasing salinity of the soil and/or irrigation water. Thus, knowing the salinity level of the soil or irrigation water that negatively impacts tropical fruit crops, including papaya, is important to alleviate salinity-induced damage to these crops. A study was conducted to evaluate physiological and growth responses of two papaya (Carica papaya L.) cultivars grown commercially in Florida (‘Red Lady’ and ‘Exp15’) to different irrigation salinity levels. Papaya seedlings were transplanted into 11.4-liter pots with Krome very gravelly loam soil; a calcareous soil collected from the papaya production area in south Florida. Each plant was manually irrigated three times per week with 1 liter of deionized water containing different concentrations artificial sea salt (Instant Ocean®) to obtain 4 salinity levels based on electrical conductivity (EC) of the irrigation water i.e., 0 (control), 3, 6, and 9 dS/m. Plants performance under different salinity levels was evaluated by determining net CO2 assimilation (A), stomatal conductance (gs), transpiration (E), the leaf chlorophyll index (LCI), and the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) on a weekly basis throughout the study. Normalized difference vegetation Index (NDVI) values derived from multispectral images were also collected weekly. After seven weeks, plants were harvested and leaf relative water content (RWC), leaf water potential, leaf area, and leaf, stem, and root dry weights were determined for all plants. Five weeks after treatments were initiated, for both cultivars, plants in the 6 and 9 dS/m treatments had lower A, E, gs, LCI, and Fv/Fm than plants in the other treatments. At the end of the experiment, plants in the 3, 6, and 9 dS/m treatments had significantly lower A, E, gs, LCI, Fv/Fm, leaf water potential, leaf area, and leaf, stem, and root dry weights than plants in the other treatments. Also at the end of the experiment, ‘Exp15’ plants in the 9 dS/m treatment had lower NDVI values than plants in the other treatments, whereas there was no difference in NDVI among treatments for ‘Red Lady’. There was no significant effect of salinity treatment on RWC. The findings suggest that 'Red Lady' and ‘Exp15’ papaya plants are unable to withstand salinity levels of 3 dS/m or higher in the calcareous agricultural soil of southern Florida.

Achachairu (Garcinia humilis (Vahl) C.D. Adams) is a slow-growing tropical fruit tree indigenous to the Amazonian forests in Bolivia. Each tree can produce over 15,000 fruit (400 kg/tree) harvested from cultivated and wild trees. It has significant horticultural potential because the fruit is considered delicious by many people who have tasted it. Thus, its commercial cultivation has extended to Brazil, Mexico, and Australia. The responses and tolerance of this species to abiotic stresses and the use of chemical priming to mitigate stress have never been reported. The study investigated the physiological, biochemical, and morphological responses to flooding and salinity, and the priming with 24-epibrassinolide (EB) to increase flooding and salinity tolerance of G. humilis. Three-year-old achachairu seedlings were used in several sequential experiments, including applying flooding, salinity, and EB priming in different combinations and durations. Physiological variables including leaf gas exchange [net CO2 assimilation (A), stomatal conductance of H2O (gs), and intercellular CO2 concentration (Ci)], leaf chlorophyll index (LCI), and the ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) were measured. Leaf and root nutrient concentrations, antioxidant responses, reactive oxygen species (ROS), and lipid peroxidation (MDA) were also measured. Results showed that G. humilis is very tolerant of prolonged flooding of up to 30 d, medium levels of salinity of up to 6 dSm-1, and the combined effect of flooding and salinity. Tolerance to these stresses was exhibited by physiological, biochemical, and morphological responses, consistent with tolerance traits, such as maintaining basal levels of photosynthesis, ion homeostasis, and nutrient balances, robust antioxidant responses to counter ROS increases, and limited lipid peroxidation, all of which may help limit physiological damage. Application of 1.0 mg L-1 EB as a foliar and root-drench before flooding or salinity treatments increased the levels of tolerance of G. humilis to salinity and flooding, most likely by reinforcing antioxidant responses which helped decrease ROS and lipid peroxidation.

Soil salinity poses a significant challenge in agriculture, disrupting the normal functioning of plants by reducing water and nutrient uptake. Olive trees (Olea europaea), common in Mediterranean regions, exhibit moderate to high tolerance to salinity, varying by cultivar. Interest in cultivating olive trees is growing in Florida’s coastal areas, characterized by poorly drained soil and low-quality groundwater, leading to salt accumulation in the root zone. The high salinity levels in these areas present a significant challenge for crop cultivation. Therefore, introducing new salt-tolerant cultivars is necessary to mitigate salinity stress. This study aimed to evaluate the plant physiological and root anatomical responses of two novel olive cultivars - ‘Oliana’ and ‘Lecciana’ - to salinity stress, assessing their salt tolerance. Eight-month-old plants were grown in pots using a sand medium under greenhouse conditions and treated with varying salt concentrations (0 mM, 50 mM, and 100 mM). The experiment followed a completely randomized design with three replications, each consisting of nine plants. Plants were irrigated at weekly intervals with half-strength Hoagland solution to meet their nutrient requirements. Height and trunk diameter were measured at four different time points (0, 15, 30, and 45 days). At the end of the trial, plants were destructively sampled for biomass, nutrient content, and root anatomical measurements at the latter three time points. Significant differences were observed in height, trunk diameter, and nutrient contents between the control and NaCl treatments. These findings serve as a baseline for the commercial development of salt-tolerant olive cultivars.

Water scarcity is challenging agricultural production, demanding more precise and efficient irrigation management. Plant-based continuous monitoring has emerged as a promising approach for detecting water stress progression and optimizing irrigation. However, its practical implementation is hindered by the complex interpretation of the sensors’ outputs and plant physiological status relationships. Plant water potential is among the most robust water status indicators and is widely used for irrigation management. Nevertheless, its measurement is time-consuming and requires skilled personnel, making it difficult to have frequent assessments. In this study, we explored the potential of using continuous water potential sensing to quantify olive water status and its response to irrigation. Specifically, we compared continuous and discrete tree-level measurements of water status using microtensiometers and the pressure chamber, respectively. The microtensiometers proved effective in capturing tree water status dynamics, enabling a prompt assessment of the impact of irrigation practices. Preliminary analyses show a good linear correlation between midday trunk and stem water potential values obtained with microtensiometers and the pressure chamber, with the former being less than 0.5 MPa lower, a difference that could be attributed to the specific measurement of each technique. Importantly, having continuous data allows the extrapolation of several water status parameters which can provide key information in addition to the single timepoint midday values. Overall, this study suggests microtensiometers can be a useful tool to optimize water application in olive orchards.

Phosphorus (P) deficiency in plants causes detrimental effects on their growth and development, as P is a key macronutrient used in various physiological, biochemical and cell signaling processes. Research has shown that P-deficient plants exhibit several symptoms such as changes in leaf coloration, root morphology, and plant growth. However, many of those studies ignore gas exchange parameters. In this research, we studied the connection between P-deficiency and carbon (C) gain and loss in southern highbush blueberry (SHB, Vaccinium corymbosum interspecific hybrids) young plants to estimate the C cost of P-deficiency. The experiment was conducted using a hydroponic system where three-month old plants of ‘Farthing’ and ‘Keecrisp’ varieties grew in individual 2-L reservoirs filled with continuously-aerated complete nutrient solution containing 15 mg/L P during a 35-day acclimation period. After the acclimation period, plants were separated into two groups and continued to grow for 56 more days (treatment period). One group ( P) was grown in the complete nutrient solution, while the second group (-P) was grown in a P-free nutrient solution (0 mg/L P). We designed and tested a whole-plant gas exchange system that utilizes two infrared gas analyzers (CIRAS-3 and CIRAS-4) to simultaneously measure root system respiration and whole-plant C assimilation. Additionally, we measured root C exudation, fresh and dry mass accumulation, and P concentration and content. We induced P-deficiency as -P plants of both varieties had mature and young leaf P concentration below 0.12% (reference deficiency level). P plants had higher P concentration after treatment period. -P ‘Farthing’ plants had 89% less daily C assimilation than P plants, while no differences were observed in ‘Keecrisp’. Daily root respiration and C exudation, considered as ways of C loss, were, 3.5 and 2.9 times higher in -P than in P plants of ‘Farthing’. Similarly, -P ‘Keecrisp’ plants had 3.8 and 2.5 times more daily root respiration and C exudation compared to those under P. Ultimately, P deficiency caused a 136% reduction in daily C gain of ‘Farthing’ plants, while there were no differences between treatments in ‘Keecrisp’ plants. Our findings suggest that responses to P deficiency in SHB are genotype-specific, and that C budget and distribution in the plant play an important role in the responses to P-deficiency.

The interactions between plants and their soil environment influence overall soil system health. Soil provides plants with the structural support, water, nutrients, and microbial interactions they need for creating biomass and for reproduction. Conventional agriculture practices degrade soil; however, small plots of native plants within agricultural settings have been shown to provide disproportionally large benefits to both ecological and agricultural landscapes. In other words, even small plots of native plants can improve soil health. Although small plots of mixed native plant species improve soil health, they offer little in the way of income opportunities for producers through seed collection and sales. However, plots of native monocultures may offer producers an opportunity to harvest and sell seeds, taking advantage of the increasing demands of the native seed market while also increasing soil health. Therefore, this study's objective is to quantify the effects of small native plant monocultures on soil health and compare them to soil health from conventional crop plots. We investigated biological indicators of soil health such as organic matter, organic carbon, and microbial communities as well as abiotic indicators like nutrient composition. We hypothesize that, compared to crop plots, native monoculture plots will have more microbial diversity and higher amounts of soil nutrients. We tested our hypothesis by comparing soil health characteristics from plots containing five established native monocultures: Dalea candida, Agastache nepetoides, Glycyrrhiza lepidota, Liatris ligulistylis, and Tradescantia occidentalis; and one crop plot planted with a corn and soybean rotation. During the second and third season of growth, monthly soil samples were taken, and soil indicator values were compared using Tukey’s HSD post hoc tests after performing an analysis of variance (ANOVA). Results suggest that native plant species influenced soil health differently than crop rotations after three seasons of growth. Compared to crop plots, soil samples from two species of native plants, Agastache nepetoides and Tradescantia occidentalis, had higher fungi-to-bacteria ratios (p = 0.0160 and p < 0.0001, respectively), and higher amounts of saprophyte biomass (p = 0.0040 and p = 0.0484, respectively). Soils from the Agastache nepetoides plots also had higher amounts of Pre18 cyclo fatty acids (p = 0.0022) and potassium (p = 0.0159). These two species of native plants show potential for improving soil health after three years of establishment. Adding these two native monocultures to marginal production land may add soil health benefits during early establishment periods while providing a marketable crop for producers.

A Water Soluble β-triketone Enriched Extract of Manuka Oil has Increased Efficacy Compared to Vinegar and D-Limonene in a Field and Greenhouse Evaluation - Casey Barickman
Weed Control in Bell Pepper after Herbicide Application in a Reduced Sunnhemp Cover Crop Population. - Peter Dittmar
Assessing the Effects of Container Sizes and Weed Densities on Weed-ornament Competition in Nursery Container Production - Debalina Saha
Herbicide-Resistant Italian Ryegrass in Oregon Hazelnut Orchards: Evaluating Nonchemical and Chemical Methods - Marcelo Moretti
Limiting Liverwort Growth by Allelopathic Effects of Organic Mulches in Ornamental Production - Manjot Sidhu
Effect of Application History on Preemergence Herbicide Persistence - Travis Gannon

Weed management strategies for specialty and organic crop production are challenging due to limited chemical weed control products with good efficacy that are cost effective. The need for new bioherbicide modes of action has become increasingly urgent in modern agriculture as most bioherbicides have nonspecific modes of action with no systemic activity. Introducing new modes of action is essential to diversify weed control strategies, minimize the risk of resistance development, and ensure sustainable weed management practices. By fostering innovation in bioherbicide development and promoting the use of novel modes of action, we can safeguard our agricultural systems, reduce the environmental impact of weed management, and maintain the ability to feed a growing global population while preserving the long-term health of our ecosystems. Manuka oil is derived from the leaves and branches of the Manuka tree (Leptospermum scoparium) and contains β-triketones. The β-triketone rich fraction contains leptospermone and inhibits a key enzyme, p-hydroxyphenylpyruvate dioxygenase (HPPD). This process directly inhibits carotenoid biosynthesis, upstream in the biochemical pathway, which causes damage to the photosynthetic apparatus and leads to bleaching of the leaf tissue which eventually kills the plant. The β-triketone extract at 2% and 4% had up to 97% control against different weed species in field and greenhouse evaluations. The β-triketone extract was significantly more efficacious verse other bioherbicides such as the 20% vinegar and 12.5% D-limonene. Additionally, the β-triketone extract was just as effective as the 2% glyphosate treatment in the greenhouse evaluation against Amaranthus palmeri and Digitaria sanguinalis. The β-triketone extract also reduced Cyperus esculentus growth by 70% at 9 days after treatment. Thus, there is significant evidence that commercializing a water soluble β-triketones enriched extract of Manuka oil can be an effective weed control strategy in crop production systems, especially in specialty and organic cropping systems where the need of bioherbicides is critically imperative.

Sunnhemp cover crop seed germination can be lowered due to poor seed quality, incorrect planting depth, or adverse weather effects. The objective of this research is to evaluate weed control by herbicides in a reduced sunnhemp population. Research trials were conducted at the Plant Science Research and Education Unit, Citra, Florida, and the Syngenta Vero Beach Research Center, Vero Beach, FL. The treatments were sunnhemp at 44.83 kg/ha, sunnhemp at 22.4 kg/ha ( no herbicide, bentazon at 1.12 kg/ha, sulfentrazone at 0.14 kg/ha, halosulfuron at 0.04 kg/ha, glyphosate at 5.5 kg/ha followed by glyphosate at 5.5 kg/ha, and oxyfluorfen at 0.56 kg/ha), and a nontreated weed fallow. Sunnhemp was planted in Citra on July 18, 2023 and in Vero Beach on July 27, 2023; herbicides were applied 2 weeks after planting when the sunnhemp were 15 to 25 cm tall. After 8 weeks of growth, the sunnhemp was mowed and the field was prepared for laying plastic and planting bell pepper. The oxyfluorfen caused significant injury to the sunnhemp; this treatment had similar broadleaf, grass, and nutsedge populations to the weed fallow. In Citra at 14 and 28 days after application, bentazon, sulfentrazone, or halosuluron had lower populations than sunnhemp at 22.4 kg/ha alone, but at cover crop termination all the cover crop treatments had similar nutsedge control. All cover crop alone and cover crop herbicide treatments had similar grass and broadleaf control at crop termination. In the bell pepper crop at Vero Beach, oxyfluorfen had greater nutsedge populations than all the other treatments. Crop yields were similar among the cover crop alone or with a herbicide. The application of a herbicide in a reduced cover crop population is not necessary for increased weed control in a fall cash crop. However, the reduced cover crop population in this study was artificially created so the sunnhemp population was equal spaced through the entire plot. If the sunnhemp is significantly impacted like the oxyfluorfen treatment, then more intense recovery action may be necessary.

Effective weed management strategies are essential for producing high-quality and successful ornamentals in nurseries and greenhouses. Weeds can affect both the productivity and quality of ornamentals, especially in containers where nutrient and moisture availability are limited, due to restricted space. The objective of this study was to determine how different types of weed species at various densities and in different container sizes affect the growth of ornamental plants. Two rounds of greenhouse experiments were conducted at the Horticulture Teaching and Research Center, Michigan State University, in summer and fall 2023. Seeds of large crabgrass {Digitaria sanguinalis (L.) Scop} and smooth pigweed (Amaranthus hybridus L.) were grown separately until they attained the 4-6 leaf stage. Liners of hydrangea {Hydrangea macrophylla (Thunb.) Ser.} and syringa (Syringa vulgaris L.) were planted in containers of three different sizes 0.67 gallons (2.54 liters), 1.5 gallons (5.67 liters), and 3 gallons (11.35 liters) containing standard bark-based substrate amended with controlled-release fertilizer. All plants received 0.5 inches (1.3 cm) of water thrice daily and were allowed to grow till they were well established. Then the weed seedlings of large crabgrass and smooth pigweed were carefully transplanted to each container-grown ornamental plant at different densities of 0,1,3,6 per pot, with the density of 0 being the control set. After weed transplantation, all pots were maintained inside the greenhouse for 8 weeks. The experimental design utilized a randomized complete block design with six replications per treatment. Initial and final growth indices of ornamentals were recorded. At 8 Weeks After Potting (WAP) fresh weights of both the weed species and the ornamentals were recorded separately. All data were analyzed in SAS by ANOVA and the Tukey’s HSD test were performed to separate out the means. Results showed that final growth indices of hydrangea were significantly higher than syringa and maximum in 3-gallon containers. Overall, large crabgrass at density of 6 was more competitive than smooth pigweed and hydrangea performed better than syringa in 3-gallon container size in competing the weed species.

Herbicide-resistant Italian ryegrass (Lolium multiflorum Lam.) presents a significant challenge in hazelnut orchards across Oregon, with confirmed resistance to multiple herbicide modes of action groups (1, 2, 9, 10, 15, and 22). Four field studies were conducted in 2023 to evaluate nonchemical and chemical methods for controlling Italian ryegrass during spring. Tested treatments included mowing at 2 km h-1, electric weeding control (EWC) at 15 MJ ha-1 (2 km h-1), and glufosinate application at 1.68 kg ai ha-1, administered once or twice. Furthermore, combinations of EWC with mowing or glufosinate were examined, resulting in eleven treatments. EWC was performed using alternating current and 30 kW (EH-30 Thor, ZassoTM), treating swaths 1.2 m wide. Assessments conducted 56 days after initial treatment (DAIT) revealed that single mowing showed no significant difference compared to untreated plots. However, when mowing was performed twice, it led to a 30% reduction in inflorescence density and an 84% reduction in weight. EWC, applied once or twice, resulted in significant decreases in Italian ryegrass inflorescence density (51-58%), weight (55-73%), and shoot weight (45-75%) compared to untreated plots, with no significant differences observed between single or double applications. Similarly, glufosinate applied once or twice substantially reduced Italian ryegrass inflorescence density (68 to 86%) and weight (73 to 93%). Combinations of EWC with mowing or glufosinate demonstrated high efficacy, achieving control rates of 89 to 96% and exhibiting comparable efficacy to two applications of glufosinate (96%). These findings suggest that EWC, when applied during the spring period, can effectively control Italian ryegrass, offering comparable efficacy to glufosinate and superior efficacy to mowing.

Liverwort (Marchantia polymorpha) is one of the problematic weeds in ornamental crop production that deteriorates the quality and aesthetic value of ornamentals. To study the effectiveness of allelopathic properties of organic mulch extracts, six different organic mulch materials including rice hull (RH), cocoa hull (CH), pine bark (PB), maple leaf (ML), shredded cypress (SC) and red hardwood (HW) were used for obtaining mulch extracts. The extracts were prepared by following the modified EPA 1312 synthetic precipitation procedure. In the lab experiment, the mulch extracts obtained were used to impregnate agar media at an increasing dose at either 1x (2ml), 2x (4ml), 3x (6ml), and 4x (8ml) rates. Ten gemmae were transferred to the culture medium in each petri dish and all petri dishes containing gemmae were maintained inside the growth chamber. Data was recorded for number of gemmae germinating in each petri dish and at the end of experiment, the length and width of the thallus derived from each gemmae were measured. For greenhouse experiment, the mulch extracts were applied to nursery containers filled with standard substrate and amended with controlled-release fertilizer for assessing the postemergent liverwort control in nursery containers. Either RH, HW, CH, ML, SC or PB mulch extracts were applied to each of the container uniformly at either 1X (15ml), 2X (30ml), 3X (45ml), and 4X (60ml) rates, at the beginning of experiment and bi-weekly until 10 weeks. Control set without any mulch extract was included as well. Percent of substrate surface covered by liverwort thalli was visually estimated bi-weekly until 10 weeks after first treatment. Fresh biomass of the thalli and number of gemmae cups in each pot were also recorded at the end of the experiment. Both lab and greenhouse experiments had four replications per treatment and were arranged in a randomized complete block design. After 1 week in the growth chamber, ML followed by SC, PB and RH extracts showed maximum suppression of liverwort gemmae germination. At 2 weeks, all rates of ML provided complete inhibition of liverwort. In the greenhouse, all the mulch extracts were able to provide complete liverwort control for the first two weeks. PB and HW mulches showed excellent liverwort control and minimum biomass of liverwort after 10 weeks as compared to other mulches. Hence, the allelopathic potential of the organic mulches can be a promising option for biopesticidal control of liverwort, and a component of integrated liverwort management.

Preemergent herbicides are commonly applied to control many annual weed species in turfgrass systems. Oxadiazon and prodiamine are pre-emergent herbicides that effectively inhibit the growth of emerging annual grasses and broadleaf weeds without harming certain turfgrass species. However, in recent years, a decline in the efficacy of oxadiazon and prodiamine has been observed by golf course managers, leading to an increase in application rates in an attempt to mitigate the issue. Therefore, the objective of this study was to characterize degradation processes that affect oxadiazon and prodiamine persistence and efficacy in order to identify solutions or mitigation strategies. Soil samples were collected from unique sites throughout North Carolina. Field studies were organized as a randomized complete block design containing 3 replications and 2 experimental runs. Treatments were arranged in a split-split plot design, where the whole plots consisted of 4 sites with histories of continuous oxadiazon or prodiamine use (never applied, applied 1-2 years, ~7 years, > 15 years), the sub-plots were 2 treatments (non-sterilized and sterilized), and the sub-sub-plots were 6 collection timings (14, 28, 42, 56, 112, and 168 days after treatment). Herbicide residue quantifications were determined using high-performance liquid chromatography. Data were recorded and converted into a percentage of the applied rate. A higher percent of oxadiazon was observed for sterilized soil (79.2%) compared to non-sterilized soil (73.7%). In the non-sterilized soil, at 14 DAT there were no differences between periods of use. However, at 28 DAT, the soil with no use history presented a higher percentage of oxadiazon (83.0%) compared to 1 and 15 years (75.5%, and 77.1% respectively). Furthermore, at 42 and 56 DAT, the soil with no history of application exhibited the highest percentage of oxadiazon among all periods of use. Findings of this study suggest that there is higher concentration of oxadiazon, meaning less degradation, in the soils with no history of application.

A Look at Heat Stress on Micro-propagated Pecan Trees - Doris Alexa Arnedo
Unraveling the role of LEA(Late embryogenesis abundant) genes in pecan stress resilience - Sahithi Pulicherla
Discovery of Early Biomarkers for the Scab Resistance of Pecan Seedlings Using Metabolomic Analysis Combined with Machine Learning Algorithms - Min Jeong Kang
Developmental Transcriptomics of Pecan Fruit in ‘Mahan’ and ‘Tiny Tim’ - June Labbancz
Pistachio Orchard Productivity Enhancement Through Molecular Marker Preselection - Ewelina Jacygrad
Fatal Flaws of Experimental Almond Varieties and Selections - Luke Milliron
Advancing Cocoa Yield Forecasting in Ecuador Using Machine Learning and Field Data Integration - Daniel Mancero
Maturity stage at harvest modulates fruit softening and quality of jackfruit - Zora Singh
Growing papaya in Mississippi - Guihong Bi

Carya illinoinensis (pecan) belongs to the Juglandaceae family, and the native region extends from Illinois, USA to Oaxaca, Mexico. Pecan is a valuable economic crop due to its nutritious and tasty nuts, and the United States produced 275 million pounds of pecans in 2022. As temperatures are increasing it is important to understand the impact on pecan trees. By 2100, the average U.S. temperature is projected to increase by about 3°F to 12°F. Plants deal with heat stress in several different ways including the production of heat shock proteins (HSPs) and their transcription factors known as heat shock factors (HSFs). HSFs initiate the transcription of genes that encode heat shock proteins (HSPs), that deal with heat stress by initiating protein folding and aid in the repair or removal of damaged proteins. In this study, we aim to look at the genetic networks that are impacted when multiple genotypes are subjected to high-heat environments. For this study, seedstocks from multiple genotypes that span the geographic region of North America were introduced into micropropagation. These include seedstocks from ‘Elliott’, ‘Apache’, ‘Cape Fear’, ‘Mahan’, ‘Giles’, ‘Sioux’, ‘Wichita’, ‘Western’, and native seedstocks of unknown genetics from Ohio. A preliminary heat stress assay was performed on a micropropagated ‘Elliott’ line by subjecting three small trees to 43°C for two hours prior to flash freezing in liquid nitrogen and comparing these to the same clonal line (three trees) that remained at 23°C. Real time quantitative reverse transcription PCR (QRT-PCR) was performed on the heat stress and control trees. Normalized gene expression indicated that CiHSP1 expression was 2X higher in the heat-treated pecan trees than CiHSP1 expression of the control trees. The additional micropropagated seedstocks listed above are being subjected to heat stress at different temperature ranges and time intervals. The replicated assays will be analyzed using RNA-Seq and qRT-PCR to determine differential gene expression of control and heat-treated trees especially between the HSPs and HSFs. These assays will help determine the gene networks that pecan trees use as they experience heat stress and will help determine how different pecan genetics that originate in different geographic regions react to heat stress.

Late embryogenesis abundant (LEA) proteins, encoded by a family of LEA genes, are vital in conferring stress tolerance in plants through their unique intrinsically disordered structure that can stabilise cellular components under desiccated conditions. While the protective capabilities of LEA proteins are well-documented across various crops, their specific roles in pecan (Carya illinoinensis), a highly nutritious and economically significant nut crop, remain largely unexplored. This gap of knowledge needs to be addressed as pecan yields face threats from escalating drought and salinity issues, intensified by ongoing climate change. This study represents the first comprehensive analysis of LEA genes within the pecan genome. We have successfully identified 332 LEA genes distributed across 15 of the 16 chromosomes in four genomes of pecan, categorized into 8 distinct subgroups based on their conserved motif regions. Synteny analysis provided a deeper understanding of their evolutionary trajectories. Utilizing extensive transcriptomic datasets, we explored the tissue-specific expression patterns of LEA genes in pecan, discovering diverse expression profiles across various tissues. Ongoing studies include promoter analysis and assessments of gene expression under abiotic stress conditions. To specifically address the impact of drought, heat and salinity, clonal pecan plants are being subjected to these stressors under controlled conditions in tissue culture and greenhouse settings. This approach aims to directly observe the physiological and molecular responses of LEA genes under realistic stress simulations. The presence of LEA genes across a vast majority of pecan chromosomes and their diverse subgroup classifications suggests a genome-wide defense mechanism potentially key to enhancing the stress tolerance of pecan trees. By understanding and harnessing these genes, our research seeks to elucidate plant stress responses at the molecular level allowing the development of genetic strategies to ensure the sustainability of pecan by mitigating adverse environmental impacts on its production. This knowledge could also be applied in a diverse array of other economically significant crops.

Pecans (Carya illinoinensis (Wangenh.) K. Koch) are globally consumed nuts and an important agricultural commodity in the United States. Scab is a devastating pecan disease, which necessitates the application of numerous fungicide sprays in the growing season of pecans. Even with the control measures, in wet years, scab infection results in great yield loss (over 50% loss in susceptible varieties) and deterioration of nut quality. Although there have been various efforts to alleviate the scab, the development of scab-resistant pecan cultivars is the most effective method to control the disease. However, current methods to assess pecan scab resistance require multiple years of field screening and complicated laboratory (microscopic) techniques. Thus, a simple and reliable method that can rapidly evaluate pecan scab resistance at an early stage of infection is necessary. In this study, metabolomic analysis with machine learning algorithms was utilized to identify early biomarkers for the scab resistance of pecan seedlings. Two pecan seedlings with contrasting scab resistance ('Pawnee' and 'Desirable') were inoculated with water (control), Pa-OK-11 (isolated from 'Pawnee'), and De-Tif-11 (isolated from 'Desirable') for 7 days. 'Desirable' seedlings exhibited resistance to Pa-OK-11, while 'Pawnee' seedlings showed moderate resistance to De-Tif-11. Both cultivars were susceptible to their respective isolates. Leave samples from each seedling were collected at different time points (0, 1, 2, 3, 4, 5, 7 days). For the metabolomics work, liquid chromatography‒mass spectrometry (LC‒MS) was employed to analyze metabolites in samples, which can cover a wide range of primary and secondary metabolisms, including carbon fixation, glycolysis, citric acid cycle, amino acid metabolism, phenylpropanoid, monolignol, and flavonoid biosynthesis. Different machine learning algorithms were compared to find differentially regulated metabolites (biomarkers) between scab-resistant and -susceptible seedling groups. With a combination of machine learning models, we obtained reliable potential biomarkers, e.g., phenolic acids, flavonoids, plant hormones, and their intermediates and precursors, involved in the early stage of scab infection. The selected markers are expected to be used to classify scab resistance levels in pecan seedlings within a week after infection, which may replace the conventional method (phenotype-based mass selection) for pecan breeding selection. In short, this research breaks the bottleneck of resistance screening in pecans and will help facilitate the early selection of scab-resistant pecan cultivars to achieve breeding goals.

Pecan (Carya illinoinensis) is a nut crop native to the United States and Mexico which is becoming an increasingly important crop globally. Juglandaceous nuts are uniquely high in antioxidants among nuts and a conversion equivalent derived from studies in mice indicates that consumption of 22-38 pecans per day may reverse metabolic disorder in an individual weighing 132 pounds, implying a role in a healthy diet. Despite this importance, relatively little is known about the molecular basis of pecan nut ontogeny compared to other nut crops, leading to difficulties in understanding the physiological issues which plague growers. Susceptibility to various biotic and abiotic disorders including pecan scab, vivipary, water split, and shuck decline are dependent upon the stage of development the pecan nut is in. To better understand the molecular basis and timing of pecan nut development, developmental time-course RNA-Seq was carried out on nuts collected from cultivars ‘Mahan’ (a large nut bearing pecan from Mississippi) and ‘Tiny Tim’ (a small nut bearing native pecan from Missouri) approximately biweekly through the growing season of 2022. Using this data, genes were grouped together into distinct developmental phases, connecting transcriptional changes to the already well-characterized ontogenic stages of pecan nut development.

There is significant variation in tree size, which determines productivity, in commercial pistachio orchards planted with UCB-1 seedling rootstocks. It has been unclear to extent to which this is due to genetic differences or environmental variation. Nurseries have tried to tackle this problem by rogueing young seedlings before they are planted in orchards. However, our data previously demonstrated that performance in the first year is a poor predictor of later tree size. Genotyping by sequencing data from experimental and commercial orchards and genome wide association studies (GWAS), combined with our chromosome-scale, high quality, genome assemblies for the parental Pistacia atlantica and P. integerrima trees resulted in two highly informative molecular markers for vigor. Based on the genomic sequence information, we developed an inexpensive, quick, and easy qPCR protocol for single nucleotide polymorphism (SNP) marker analysis. We were able to predict the improved size distribution that extant orchards would have had if this marker had been used to rogue seedlings prior to planting in the orchards. We want this marker to make it available for nurseries to rogue out trees which would exhibit low vigor and productivity later in an orchard.

The California almond industry has funded multiple, multi-site almond variety evaluation trials over the last several decades. These field trials have previously evaluated many of the varieties that are now the most widely planted in California. Although, field evaluation trials are helpful for revealing which varieties are promising, they are, perhaps, most valuable to the industry for revealing which varieties/selection have serious flaws and should not be planted by growers. Thirty named cultivars and numbered breeder selections were planted in three replicated commercial orchards across California’s Central Valley in 2014. Of these 30, as of April 2024, one numbered selection Y116-161-99 from the USDA has been commercially released as ‘Yorizane’. However, nine of the 30 varieties/selections were dropped from further evaluation in the trial in 2022 for a variety of reasons: low yield (five), lack of interest by the breeder (two), extremely early bloom timing (one), and poor harvestability (one). Of the 21 still being evaluated in 2024, many have one of these major flaws, or additional flaws, that will likely prevent commercial adoption, including a high percentage of double kernels, susceptibility to bacterial blast (Pseudomonas syringae pv. syringae), Botryosphaeria canker disease susceptibility, hull rot susceptibility, and a high percentage of kernel creases or twins, just to name some of the additional flaws. Even if a variety/selection has high yield, good kernel quality, and none of these major flaws documented after ten years of evaluation (e.g. Y117-91-03 from USDA), further observation in the UC trial sites or in the orchards of early adopters may reveal important flaws that prevent sustained and widespread variety adoption. This long-term challenge is why some believe it takes decades to prove a new scion variety. The wide diversity of potentially fatal flaws underscores the need for cultivar evaluation to take place by a third-party like UC Cooperative Extension in long-term replicated trials to reduce substantial financial risk to the grower to the greatest extent possible. Keywords: Prunus dulcis, almond, variety evaluation, breeding, nut crop

Enhancing Public Garden Experiences: Utilizing QR Codes and Videos for Plant Identification and Education - Bailey Singleton
Educational Signage in a Community Garden can Assist in Volunteer Learning - Jonah Trevino
Marigolds - An Overlooked Cut Flower Alternative - Alessandro Holzapfel
Improving Military Community Reintegration: The Effects of Plant-related Jobs on Military Service Member Mental and Physical Health - Alicia Thomas
Evaluating the Impacts of Climate Change on Urban Tree Performance and Survival - Teagan Young
Managing Drift in Vegetable Operations: Extension Risk Management Herbicide Workshops - Kathryn Fontenot
Native Trees for Public Gardens: Building a University Teaching Collection for Increased Student Learning, Visitor Engagement, and Carbon Sequestration - Lauren Errickson
Future Directions of Horticultural Research Among Botanical Gardens and Arboreta in the United States - Michael Opgenorth

Public gardens play a crucial role in promoting horticultural education and appreciation. Proper plant signage can further enhance a visitor’s learning experience. This project provides partner gardens with trusted horticulture information while further utilizing Oklahoma Gardening content, produced by Oklahoma State University Extension. Oklahoma Gardening, a research-based, how-to gardening television show, airs weekly on Oklahoma Educational Television Authority (OETA), a PBS affiliate. This project created a virtual, educational experience for visitors of participating gardens. Eleven public gardens and educational demonstration gardens located in rural and urban settings throughout Oklahoma were provided with 5-15 signs depending on the size of the garden, the availability of in-season plant material, and the applicable video content. This approach leverages the recent widespread adoption of QR codes, allowing visitors to access plant information effortlessly from Oklahoma Gardening. Many of the selected gardens provide free entrance to the public, offering a horticultural experience to all. However, this can reduce the garden’s operation budget and limit their ability to provide adequate educational signage. The objective of this project is to help these public gardens increase their horticulture educational interpretation. These QR code signs not only provide gardens with seasonally appropriate plant identification signage but also offer visitors videos about the plants they are observing. Furthermore, for open-access public gardens it can be difficult to quantify visitation. By utilizing dynamic QR codes the quantity and time of scans is captured. This allows for tracking of the usage of each sign and which plants are most popular. This information is then shared with participating gardens. Public gardens are often visited by tourists as well. This project expands Oklahoma Gardening and OSU Extension beyond television and YouTube to reach an audience in the public garden space. The dynamic QR code scans provide the phone’s registered city, state, and country, giving approximate geographic locations of garden visitors. After a year of placing the signs, we have identified clicks from 23 states, and 5 additional countries. This project was funded by Oklahoma Department of Agriculture, Food, and Forestry Specialty Crop Block Grant.

Volunteering issues in community gardens have been an ongoing problem and have resulted in high turnover and untrained volunteers that may not have the skills to appropriately staff a community garden. The problem of having to train or have dedicated staff at a garden to assist volunteers is that often community gardens are not funded, or garden staff are stretched too thin. To inspect factors in volunteerism in community gardens, researchers sent out a ten-question survey to head community garden leaders (N=51) across the U.S. Overall, researchers found that many gardens perceive educational opportunities and the people that attend the garden as successful elements, while volunteer retention and education, along with signage issues, were the most prevalent problem. Finally, when asked about signage, most signs turned out to be purely informative and attractive, with few playing educational roles. Researchers concluded that educational signage may play an important role in the garden that many community gardens are missing. To understand further how educational signage plays a role in people’s understanding of a subject, researchers have developed another survey that is currently being distributed to the public. The data from this survey will allow researchers to more effectively use signage to not only attract but educate and train volunteers to relieve some of the burden from community garden staff.

Especially the floral industry is dependent on fashion trends and changes in taste that dictate the colors and styles of arrangements. As it turns out, when it comes to marigold cut flowers, certain customers have been traditionally underserved in the southeastern United States. Research conducted by the Louisiana State University and Mississippi State University indicate that Marigolds are not only a very viable alternative to traditional cut flowers but also a worthwhile investment for commercial growers. Further research indicates that specific cultures and religions prefer marigolds for celebrations and holidays representing a relatively large customer base with considerable purchasing power that has previously gone unnoticed by the floral industry in the southeastern United States. Findings suggest marigolds have the potential to increase the floral industry’s market share and attract new customers that it previously failed to attract. Additionally, many celebrations and holidays for which marigolds are desired are during a time of the year when demand for flowers is typically low. Marigolds should therefore be considered for season extension.

Military members are a unique and diverse group making up 7% of the U.S. population. After completing their military service many return home and struggle with reintegration back into civilian life due to mental and physical ailments they obtained during enlistment. One of the first steps of civilian reintegration is acquiring a job. A type of job that military members enter is in plant-related fields. Research on the passive and active interaction with plants and its benefits, has been conducted extensively. However, it is not yet known how specific jobs that require working with plants or being in nature can help improve military member health and if they have therapeutic benefits. To evaluate this, part 1 of an online survey ascertained demographics and part 2 was created based on the National Veteran’s Survey and the VR-36 which looked at participants’ physical (PCS) and mental wellness (MCS). Results show that most of the military participants (N=148) were in the 25-30 year and 40-50-year-old range, Caucasian (70.9%) males (68.9%) involved in Army (44.6%) and Marine (24.3%) branches of the military and honorably discharged or retired. Military members in plant-related jobs scored in the top 3 job categories for PCS (49.1) and MCS (45.0), while Health related jobs were top for MCS (53.6) and those retired were top for PCS (49.7). Overall, those in plant, health, and retired jobs described them as relaxing, easy, and physical. Military in rural locations also had lower MCS in comparison to those living in urban centers. The findings from this research suggest that plant-related jobs could offer military members an opportunity to improve their mental and physical health, while helping with job retention and community reintegration.

Climate change is expected to lead to the increased frequency and intensity of natural disasters, which will adversely affect urban tree populations. As a result of rising surface temperatures, USDA Hardiness Zones are projected to shift northward. Healthy urban trees can offer benefits which may offset some of the effects of warming. Therefore, species adaptability to urban conditions needs to be considered, and we need to understand the predicted impacts of warming better in order to design and plant more resilient urban forests. Thus, in the Fall of 2022, protocols began developing to evaluate the following areas of concern: 1: Identify underutilized tree species that might perform well in future climates. A state-wide survey was distributed to green industry professionals to guide species selection for field trials across three hardiness zones in Florida (8b, 9a, and 10b). 2: Analyze the variability of commonly used irrigation technologies on tree establishment. The project compares two commonly used irrigation bags (i.e., TreeDiaper and Treegator) to hand watering to determine labor inputs, time to establishment, and overall tree performance. 3: Determine the effects of increased temperatures on tree species commonly planted in Florida. Temperature-controlled greenhouse experiments will be used to determine the heat tolerance of 6 tree species based on future climates. 4: Analyze parking lot plantings and evaluate the impact of the mitigation of the urban heat island effect. Several randomly selected parking lots in Florida will be looked at to determine their suitability for planting based on the adverse growing conditions associated with urban heat islands. The above studies offer a proactive approach to better understanding the potential effects of warming and provide practical solutions to minimize the impact.

Herbicide drift from the site of application into non-target areas can be devastating to the environment and to neighbor operations. Crop injury will occur from drift and improper management of herbicides within an operation. Environmental conditions, applicator off-label usage and accidents are often the cause of herbicide drift. Prevention and communication are the most important strategies in managing off target application of herbicides. Two workshops were held in Louisiana. Vegetable producers, Department of Agriculture inspectors, county agents, and crop producers were invited to both workshops. Pre and post tests were given to all participants to measure general herbicide application and rule knowledge. The workshops consisted of fields showcasing tomatoes and squash with 4 herbicides sprayed on them to showcase what drift looks like. Control (non-sprayed plants) were also in the field. All plots were replicated but only half labeled. The participants learned what the symptoms looked like, then worked in teams to identify the non-labeled plots. Participants also learned how to properly clean tanks and nozzles, as well as listened to speakers about the economic loss from off target herbicide drift, and rules and regulations from Louisiana Department of Ag and Forestry specialists. 77% of the participants could identify round up damage by the end of the workshop, whereas only 40% could identify 2, 4D damage. All participants increased knowledge in tank cleaning and cross contamination prevention by the end of the workshop. and All participants gained knowledge in the documentation of crop loss economic questions at the end of the workshops.

Changing climate patterns challenge the long-term health and survivability of common mid-Atlantic U.S. tree species, including climax species such as oaks, elms, and beeches. Evidence of tree loss in natural and managed ecosystems and residential areas demonstrates the need for public gardens to consider alternative species that will adapt to changing conditions, maximize carbon sequestration, and provide aesthetic value. University-affiliated Rutgers Gardens has long served to demonstrate landscape best practices and species selection for students, industry professionals, and homeowners; additionally, carbon sequestration has become a primary function. Continuing a tradition of education, Rutgers Gardens is creating a Native Trees teaching collection including over one hundred native species selected for their ecosystem functions, ecological niche, and landscape aesthetics, on an approximately four-acre site with the goal of maximizing carbon sequestration and educational value. Selected specimens include those native to New Jersey and the wider mid-Atlantic region and/or southeastern United States. This allows for a comprehensive collection that supports larger ecosystem functions, especially as tree species composition in the broader region is likely to shift with time. As major tree species are lost due to climate-influenced changes in pest, disease, and environmental pressures, preparing for continuous carbon sequestration by including species likely to thrive in our changing climate will maximize the environmental benefit. By including a mix of small, medium, and large (at maturity) trees, the design maximizes ecosystem niches occupied throughout the planting area and provides a comprehensive demonstration for students, homeowners, and industry professionals, modeling native trees for consideration in landscape plantings throughout the state. Specimens include straight species, as well as cultivars within the genera to demonstrate variability in true native trees and “nativars,” or cultivars of native trees. A density of approximately 25 trees per acre planted allows for the integration of new trees with existing specimens, including trees and shrubs that represent historical iterations of present-day Rutgers Gardens, and accommodates the design of accessible paths and gathering spaces between plantings to maximize educational opportunities. Public gardens present many opportunities for education and demonstration, especially within a university setting. Yet, challenges exist when considering complex land use history, student and faculty needs, visitor expectations, and the interests of diverse stakeholders such as members, volunteers, and staff of public gardens. Lessons learned include the importance of positive and clear communication among stakeholders to ensure project benefits are recognized and shared for educational and ecological success in public spaces.

Botanical gardens and arboreta maintain globally important collections for conservation and education with efforts to constantly strive for excellence in propagation, cultivation, and collection preservation. Methods of cultivating plants, learning from successes and challenges, with the ability to disseminate that knowledge is paramount for improving techniques and outcomes. However, the underlying field of horticultural research is not well defined, and results of plant cultivation techniques are often only shared informally rather than published. We explored how horticultural research practitioners perceive the field of horticulture research and excellence, how they are involved, and the most urgent needs of future horticultural research among gardens and arboreta. We conducted an internet-based survey of the status of horticultural research amongst the United States members of the American Society for Horticultural Research (ASHS), American Public Garden Association (APGA), Botanical Garden Conservation International (BGCI), and the Interactive Community of Arboreta (ArbNet), Level II, III, and IV members. 128 respondents from 116 institutions across 34 of the United States completed the survey. As conservation needs, changing agricultural paradigms, and climate change impacts continue to increase, we find future research needs are increasingly holistic and focus on species and variety conservation, ecology, and mitigating pests and diseases. The respondents were variously involved in horticulture research and the main challenges were funding, time, and personnel resources. Horticultural knowledge is largely practical and shared informally and there is a need for recognition and means of sharing practical research as well as technical research. This study presents a new framework for horticultural research supporting the horticulture community with the conceptualization, communication, and implementation of horticultural research.

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, Allison Fron, Miro Stuke, Hsin-Wu Hsu, and Soo-Hyung Kim, University of Washington, United States
  Climate Ready Landscape Plants Trialed in Seattle, WA (20 mins)
  Summary: Water conservation through selecting water-wise plants in the horticulture space is fundamental to reduce landscape water use in a changing climate. As part of the Climate-Ready Landscape Plants project, 15 taxa were evaluated in Plot 1 during 2021-2022 seasons and 12 taxa in Plot 2 during 2022-2023 seasons at the University of Washington Botanic Gardens in Seattle, WA. Plants were installed in spring of the first year and irrigated amply at a maintenance level (80% ET0) for the first summer to establish the plants before the irrigation treatments were applied. All plants were subjected to one of three deficit irrigation treatments during the second year from June to September. The treatments were based on the Water Use Classification of Landscape Species (WUCOLS) categories corresponding to high (80 % ET0), moderate (50 % ET0), and low (20 % ET0) water need. Most taxa tested in the trial in Plot 1 exhibited statistically comparable ratings on overall appearance across three irrigation treatments and thus are deemed suitable for ‘low’ irrigation in sites similar to ours in the region. In Plot 2, taxa similarly did not exhibit statistically different overall appearance ratings across the treatment levels, though some significant differences in growth were observed. Well performing plants across the two plots include Lagerstroemia ‘SMNLICBF’ Center Stage® Red, Vitex ‘SMVACBD’ Blue Diddley and Physocarpus Little DevilÔ. These studies contribute valuable datapoints into selecting location specific taxon for reducing landscape water use while achieving satisfactory aesthetic qualities and growth. 
• Ursula Schuch, University of Arizona
  Minimum irrigation for shrubs to thrive in an arid climate
  Summary: Shrubs growing in Tucson, AZ were irrigated with three levels of irrigation (20%, 50% or 80%) based on local reference evapotranspiration (ETo) to assess growth and plant quality. Irrigation was applied 4, 12, and 21 times between April and October 2023 for the low, medium, and high irrigation, respectively. Vitex x ‘Helen Froehlich’ had the highest overall appearance rating, largest canopy growth, and 100% survival at the low irrigation treatment throughout the season. Other top performers were Lantana x ‘New Gold’ and Lantana camara ‘Bloomify Red’, followed by Calliandra californica ‘Mexicali Rose’, Anisacanthus quadrifidus v. wrightii 'Mexican Fire‘, Leucophyllum x ‘Purple Rain’, and Hesperaloe parviflora ‘Straight Up Red’. Dalea capitata ‘Sierra Gold’, Eremophila glabra ‘Mingenew Gold’, and Caryopteris × clandonensis 'Blauer Spatz' Sapphire Surf had average overall appearance ratings over the season above the minimum acceptable aesthetic rating, however, they had lower ratings during some of the hot summer months. Growth in response to irrigation differed between taxa with some responding to more water with increased canopy growth and others showing no difference regardless of the irrigation treatment. Ten of the 15 taxa studied are recommended to grow in the landscape with 20% of ETo in the low desert in Arizona, but 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 twelve shared ornamental plants to deficit irrigation were investigated. Eight plants per species were randomly assigned to one of three 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.