ASHS 2024 Conference

Cover Crop Windbreaks for Slowing Biodegradable Mulch Deterioration and Improving Bell Pepper Productivity. - Caleb Wehrbein
Influence of Plastic Mulch Color on Yield and Quality of Day-neutral Strawberries - Tricia Jenkins
Exploring sustainable mulch solutions: a comparative study in strawberry production systems in northwestern Washington - Nayab Gull
Shade level effects on fruit yield of habanero chili (Capsicum chinense Jacq.) - Juan Carlos Diaz Perez

Polyethylene mulch films have become a dominant production practice to increase the yield potential of high value crops, but they are a significant source of environmental contamination. Alternatively, biodegradable mulches are a potentially sustainable alternative , but are less popular among growers as they vary in durability and performance in the field environment. Cover crops when sufficiently tall may be able to improve biodegradable mulch durability by reducing wind intensity within a mulched bed. To quantify the utility of a cover crop windbreak, we tested the effect of a fall-planted, 6ft wide strip of cereal rye planted parallel to the southern side of mulched bell pepper beds. Whole plot treatments included presence or absence of rye and split plot treatments included a comparison of polyethylene mulch, biodegradable mulch, and a bare ground control. Day windspeeds were reduced in peppers protected by a south-facing cereal rye strip by 60% relative to unprotected peppers. Large hole occurrences in biodegradable mulch were reduced by 50% and small holes by 15% in peppers protected by a cereal rye strip relative to unprotected peppers. Peppers grown behind the cover of cereal rye had a 42% reduction in leaning plants compared to peppers without cereal rye. Stomatal conductance was increased by 27% in peppers protected by cereal rye relative to unprotected peppers as a result of reduced windspeeds, though there were no differences in fruit yields. Results suggest cover crops can extend the useful life of biodegradable mulch films, which may help address a common barrier to adoption. Ongoing research aims to better understand the effects of the cover crop on crop health, yield, and quality.

High tunnel production of day-neutral strawberries is a promising production system in the central U.S. The use of different colored plastic mulches in a high tunnel production system can vary the microclimate around plants and alter yield and fruit quality. This study was conducted to identify the most appropriate color plastic mulch in a high tunnel production system as it relates to yield and fruit quality. The experiment was conducted at the Kansas State University, Olathe Horticulture Research and Extension Center in 2020 and 2021 using a split-plot, randomized complete block design. We evaluated six plastic mulches (black, white, striped silver, silver, red, and green) and two day-neutral cultivars, ‘Albion’ and ‘Portola’. Soil temperature and UV light reflected from the mulch were measured to monitor microclimate modifications. Fruit quality was assessed by overall visual quality, color, soluble solids content, titratable acidity, sugar/acid ratio, total phenolics, and anthocyanin content of strawberries. 'Portola’ produced greater yields than ‘Albion’, but ‘Albion’ had better fruit quality. The plastic mulches altered the reflected UV light and soil temperatures. During the mid and late season, the silver mulch had higher fruit yields than the red and green mulches, likely due to its ability to limit solar warming during warm production months. The mulches had inconsistent impacts on fruit quality. Overall, the silver mulch maintained the best microclimate for day-neutral strawberry production in high tunnels.

Agricultural plastic mulch made from non-biodegradable polyethylene (i.e., “PE mulch”) provides many horticultural benefits. However, PE mulch requires annual removal and disposal, which generates large volumes of plastic waste that is rarely recycled and can become a pollutant. Incomplete removal of PE mulch also can leave behind plastic fragments that threaten soil and ecosystem health. To address these challenges, soil-biodegradable mulches (BDMs) have emerged as a potentially more eco-friendly alternative. BDMs are designed to provide the same advantages for specialty crop production as PE mulch and naturally biodegrade when incorporated into the soil. In addition, non-biodegradable reflective mulch has emerged as a promising mulch technology that may reduce key insect pests. The objective of this research was to evaluate the impacts of different mulch technologies, including soil-biodegradable and reflective mulches, on horticultural and pest dynamics in day-neutral strawberry (Fragaria×ananassa cv. Albion) in northwest Washington. Seven mulch treatments were established in a randomized complete block design with four replications in 2023. Treatments included green and black BDM made with ecovio and Mater-Bi feedstocks, non-biodegradable metalized mulch, and controls of black PE mulch and unmulched plots. Yield from all mulch treatments did not differ significantly from black PE control except for the green BDM made with ecovio feedstock. The green BDM made with ecovio resulted in significantly lower (32%) yield, similar to unmulched control. Lower yield may be attributed to the rapid deterioration of the green BDM treatments, which lacks carbon black and deteriorated more rapidly compared to other mulch treatments. However, black BDM made from MaterBi feedstock and metalized mulch were 37% and 11% less deteriorated than PE control respectively. Additionally, all mulch treatments suppressed weeds better than the unmulched control and were not different from black PE mulch. Aphid and thrips populations were highest in unmulched plots, whereas metalized mulch had fewer thrips (on sticky cards) and fewer aphids (on leaves) than all other treatments. Overall, the study highlighted that black BDM performs similarly to PE mulch with regards to potential weed suppression and maintenance of yield, whereas the rapid deterioration of green BDM could effect the soil microclimate and subsequent plant growth. Despite rapid mulch deterioration, the study did not observe compromised weed management. Metalized mulch may contribute to reducing pest populations but impacts on pollination and biological control remains unknown. Additional research on soil health effects is required given the fate of BDMs is in-soil incorporation.

Habanero chili fruit is shiny, orange, or red, about 5 cm long, and very pungent (200,000 to 300,000 Scoville heat units). It is popular in Mexico, Central America, and the Caribbean, although it is increasing in demand in the U.S. There is reduced information on chili production under shade nets. The objective was to determine the effects of shade level and cultivar on the fruit yield of habanero chili. The study was conducted in Tifton, Georgia, under field conditions in two seasons. Habanero plants were grown using raised beds, black plastic film mulch, and drip irrigation, following the University of Georgia extension recommendations for bell peppers. The experimental design was a randomized complete block with four replications and 10 treatments (5 shade levels x 2 cultivar combinations). Habanero chili ‘Kabal’ and ‘Kukulkan’ were grown at 0% (unshaded), 30%, 47%, 62%, and 80% shade levels. Marketable fruit number and yield decreased quadratically with shade level, although there were no statistical differences in marketable yield for plants in unshaded conditions and 30% and 47% shade levels. Mean marketable yields were 33.6 t/ha (unshaded) and 5.7 t/ha (80% shade level). Less than 2.5% of total fruit were affected by sunscald and blossom-end rot. Total and marketable fruit numbers and yields and individual fruit size were higher in ‘Kukulkan’ than in ‘Kabal.’ In conclusion, although shading increased fruit size, it did not improve marketable yield compared to unshaded conditions.

Can Hedge-Pruning Reduce Water Needs In Southeastern United States Pecan Orchards? - Bailey Rayfield
Leaf Anatomical Traits and Water Use Efficiency in Four Pecan Cultivars - Sarahi Bracamontes
Performance of Five Early-harvest Pecan Cultivars in South Georgia - Patrick Conner
Enhancing Pecan Tree Resilience Against Spring Freeze Events: Insights from Secondary Bud Dynamics and Carbohydrate Analysis - Lu Zhang
Biochar in Pecan Orchards: Unraveling Water Stress Dynamics for Sustainable Irrigation Management - Jamin Miller
Evaluating Soil Management Impacts on the Pecan Orchard Mycobiome in the Semi-Arid Southwestern United States - McKenzie Stock

Pecan (Carya illinoinensis) trees have experienced higher density plantings which enhances the need for better water use efficiency to increase the sustainability of the orchard. The implementation of hedge-pruning allows for better light penetration as well as more efficient water use in the humid climate of the southeastern United States. The objectives of this study were to determine if irrigation rates can be reduced on hedge-pruned pecan trees with no loss in pecan yield or nut quality. The study is a split-plot design with pruning serving as the main plot effect and irrigation serving as the split plot effect. On hedge-pruned trees, all growth beyond 8’ from the trunk on the East side of the tree was pruned in year 1 and on the West side of the tree in year 2. Trees were topped on each side in their respective years at an angle with a peak at 40’. No pruning will be done in year 3. Hedging treatments are arranged in three tree blocks with each irrigation treatment occurring once per block as follows: 1) 100% irrigation; 2) 50 % irrigation; 3) non-irrigated control. Hedged blocks were replicated four times, and the non-hedged blocks were replicated three times. Among the irrigation regimes, there was no statistical difference between treatments indicating that, under the environmental conditions observed, less water is sufficient for pecan production, regardless of pruning treatment. Although, there has been no improvement in yield from the hedge-pruned trees, percent kernel has increased in the hedged trees compared to the non-hedged trees, suggesting an enhancement of pecan nut quality with hedge pruning.

The leaf surface and interior structure can affect photosynthesis and transpiration rates associated with water use efficiency. Several studies have assessed pecan (𝘊𝘢𝘳𝘺𝘢 𝘪𝘭𝘭𝘪𝘯𝘰𝘪𝘯𝘦𝘯𝘴𝘪𝘴) leaf anatomical traits and established differences between cultivars; however, the effect of these traits on water use efficiency across cultivars has not been established. Understanding the relationship between leaf anatomical structures and water use efficiency across pecan cultivars allows for the identification of those that are well suited for water limited environments. In this study, we examined the leaf mesophyll layer thickness (µm), trichome density (trichome mm⁻²), stomatal density (stomata mm⁻²), and stomatal pore area (µm²) of four pecan cultivars (‘Wichita’, ‘Western’, ‘Pawnee’, and ‘Lakota’; all grafted to clonally propagated rootstocks). Leaves were collected at the NMSU Leyendecker Plant Science Research Center, and their cross-section and abaxial surface were imaged using light and scanning electron microscopy, respectively. ‘Lakota’ leaves had the thinnest palisade mesophyll layer and thickest spongy mesophyll layer relative to total leaf thickness. The stomatal density of ‘Pawnee’ was significantly less than the other cultivars, but no significant differences in stomatal pore area were observed. Intrinsic water use efficiency, calculated as ratio of the carbon assimilation rate to stomatal conductance to water vapor, was obtained using a leaf gas exchange meter on three separate days. A stable carbon isotope composition analysis was also conducted to provide insight into the leaf’s longer-term water use efficiency. The results showed that the intrinsic water use efficiency of ‘Lakota’ was different from ‘Western’ on one of the days; however, differences between cultivars were not significant when averaged across the measurement dates. Furthermore, the relative ¹³C abundance and ¹³C discrimination did not have significant differences across the four pecan cultivars evaluated, suggesting that differences in leaf anatomical traits did not influence the water use efficiency of these samples.

Five pecan (Carya illinoinensis) cultivars were evaluated over 15 years in a trial at Tifton, GA, USA. Trialed cultivars included the standard early cultivar Pawnee, and the more recent releases Byrd, Morrill, Lakota, and Treadwell. Actual yield were measured for each tree each year and a 50-nut sample was taken to determine nut quality. Trees were evaluated for leaf and nut scab infection (Venturia effusa) and black aphid (Melanocallis caryaefoliae) damage. ‘Pawnee’ yielded significantly less than all the newer cultivars which had similar cumulative yields. However, ‘Byrd’, ‘Lakota’, and ‘Treadwell’ had significantly more yield alternation than ‘Pawnee’ and ‘Morrill’, with reduction of nut quality in the “ON” years. ‘Pawnee’ was the earliest cultivar and produced excellent quality nuts, but yields were mediocre. ‘Lakota’ had excellent scab resistance, but overcropped resulting in inferior quality, and should only be grown in orchards were crop loads are controlled by hedging or tree shaking. ‘Byrd’ and ‘Treadwell’ are very scab susceptible and also need crop load control, making them poorly suited for south Georgia. ‘Morrill’ had consistent cropping and excellent nut quality but is also very scab susceptible and should only be grown with excellent disease management practices.

Pecan growers face significant challenges in protecting their crops from the spring freezes that devastate yields. Conventional freeze protection methods are impractical for the large, tall trees. This study investigated the dynamics of the secondary bud break in pecan trees, a mechanism that ensures yield when primary buds are damaged. In three pecan cultivars ('Pawnee,' 'Kanza,' and 'Maramec') we characterized the sprouting potential of secondary buds after the primary buds were cold damaged. Primary bud shoots were collected at three different bud growth stages: outer bud scale shed stage, inner bud scale shed stage, and early bloom stage. The shoot samples held at 6°C to terminate primary buds’ growth. The cold treated shoots were then held in growth chambers set to mimic spring humidity, temperature, and light conditions. The percentage of branches with secondary bud break was recorded. The carbohydrate levels (sugar and starch) were measured in the apical shoots treated at the outer bud scale shed stage. The results showed variation among cultivars in the number of shoots with secondary buds and the stage at which primary buds were terminated. The ‘Kanza’ and ‘Pawnee’ cultivars produced more secondary buds when the primary buds were cold damaged in the outer bud scale shed stage. The ‘Maramec’ cultivar produced more secondary buds when the primary buds were cold damaged in the inner bud scale shed stage. The A carbohydrate analysis of the three cultivars demonstrated a correlation between successful secondary bud break and elevated carbohydrate levels in the one-year-old shoots. Cultivars with higher secondary bud break rates, 'Kanza' and 'Pawnee', had higher carbohydrate levels than 'Maramec.' These findings suggest that higher carbohydrate levels in one-year-old shoots facilitate successful secondary bud break following spring freeze damage to primary buds. This research suggests developing production practices to improve tree carbohydrate levels in the late summer and fall could potentially protect pecan production from spring freeze damage.

Pecan orchards in the southwestern United States face significant challenges due to persistent drought conditions that adversely affect yield and nut quality. Pecans are recognized as the most water-intensive crop in the region, and therefore require innovative strategies to optimize the available irrigation water. This study explores the use of pecan wood-derived biochar as a soil amendment to enhance the soil water-holding capacity and alleviate water stress in pecan orchards. We conducted field experiments during the summer of 2023 in a flood-irrigated pecan orchard located in the Mesilla Valley, New Mexico, USA. We accounted for the irrigation gradient in a flood-irrigated orchard by using a randomized complete block design with four blocks, each containing three equidistant trees from the irrigation valves. The trees within each block were randomly assigned to one of three biochar application rates: 0 kg/ha (treated area), 6300 kg/ha, and 12600 kg/ha. The treated area was situated within the herbicide strip, spanning 9.14 m in length – centered on the tree – with 1.22 m on either side of the tree. To assess tree water status, two leaf samples from the lower shaded canopy were covered in aluminum foil bags for a minimum of 15 minutes before mid-day stem water potential was measured. Mid-day stem water potential was measured throughout the growing season near the end of each irrigation dry-down cycle. For each tree, we calculated the average mid-day stem water potential and then performed an ANOVA to compare the averages across the treatment groups. In the five months after biochar application, there were no significant differences in tree water status across the treatment groups. This highlights the need for more research to study the interactions among soil moisture content, biochar amendment applications, and pecan tree mid-day stem water potential. This study contributes to the ongoing discourse that calls for enhancing crop water use efficiency in arid regions by providing a foundation for future studies that seek to use biochar as a sustainable agricultural practice in pecan orchards.

Pecans hold significant agricultural importance in the water-limited Southwestern United States, underscoring the need for sustainable soil management practices in pecan cultivation. Recognizing the intricate relationship between soil treatments and the soil microbiome is essential to develop effective orchard soil management strategies. Soil fungi, particularly root-associated mycorrhizal fungi, are vital in facilitating water and nutrient uptake, protecting against pathogens, and enhancing overall orchard health and productivity. Soil management may impact the fungal community composition of Southwestern pecan orchard soils. Various soil management strategies are implemented in pecan orchards, including varying soil cover or applying mycorrhizal and bacterial inoculants. These techniques alter the soil environment, which may change the soil fungal biodiversity. This study investigates the impact of diverse soil management techniques on the soil mycobiome within a twelve-year-old ‘Pawnee’ pecan orchard in New Mexico. In a randomized complete block design, eight treatments of various soil cover – bare soil, cover crops, compost, or a combination of cover crops and compost – each either with or without mycorrhizal and bacterial inoculants, were applied to evaluate their effects on soil fungal diversity. Laboratory analyses, including DNA extraction, PCR amplification, and Illumina sequencing, were performed, alongside physiochemical testing for soil pH, electrical conductivity, and mineral nutrient content. The resulting sequence data were analyzed to provide insights into the complex interactions between soil management practices and microbial communities. Sampling conducted during the 2022 Spring and harvest seasons revealed significant differences in alpha and beta diversity between roots and bulk/rhizosphere soil (P < 0.10). Significant differences in alpha and beta diversity of fungi based on treatment were also observed, highlighting the potential influence of soil management practices, including soil cover and inoculant use, on fungal community composition. Our study offers valuable insights into the temporal changes in the community structure of pecan orchard fungi when treated with different soil amendments. Understanding how soil management practices influence the soil mycobiome can inform more sustainable pecan cultivation practices. By optimizing soil management strategies to support beneficial fungal communities, growers may enhance soil health, water and nutrient availability, and plant resilience to environmental stress.

A Comparative Study Analyzing Light Lengths for the Growth of Rex Butterhead Lettuce Utilizing GREENBOX Technology - Mya Griffith
Evaluating the Feasibility of Lettuce Crop Cultivation with Reclaimed Water Utilizing GREENBOX Technology - Mya Griffith
The Assessment of Different Growth Mediums for Plug Cultivation in a Controlled Environment - George Buss
Comparative Analysis of Lettuce Growth Using Compost Versus Conventional Soil - Sofia Huber
Feasibility of Plug Production Utilizing Digestate From Home Water-Energy-Food Systems (H-WEF) - Rory Dunn
From Flower to Fruit: Growing Degree Days and Peach Ripening - Matthew Almy
Enhancing rose propagation using moisture sensor-controlled irrigation and LED supplemental lighting in greenhouses - Braylen Thomson

The development of GREENBOX technology addresses the challenges posed by rapid population growth, which intensifies the demand for agricultural resources essential for cultivating and distributing fresh produce, including arable land, water, and nutrients, to both rural and urban areas. Utilizing principles of Controlled Environment Agriculture (CEA), GREENBOX technology optimizes growth conditions for leafy green crops by leveraging existing urban infrastructure and readily available commercial equipment. GREENBOX technology allows for precise control over environmental variables such as temperature, humidity, light intensity/spectrum, and nutrient delivery, thereby enhancing the growth performance of leafy greens. We were interested in assessing the feasibility of utilizing reclaimed water for crop production as preliminary experiments employing GREENBOX technology that employed a standard nutrient solution comprising a blend of 5-12-26 and 15-0-0 Calcium Nitrate for crop production. This study's primary objective was to conduct a comparative analysis of Lactuca sativa Rex Butterhead Lettuce production using the standard nutrient solution as the control (Treatment 1), and Reclaimed water or treated wastewater supplemented with additional nutrients (Treatment 2). The assessment focused on measuring crop biomass and productivity and environmental conditions associated with each nutrient solution to identify any significant differences. Biomass parameters, including wet weight, dry weight, leaf area, leaf count, and chlorophyll concentration, were measured alongside derived data such as Leaf Area Index (LAI), Specific Leaf Area (SLA), and biomass productivity. Statistical analysis of the biomass data was conducted to discern differences in biomass parameters between crop growth using both hydroponic solutions. Both treatments yielded Rex Butterhead lettuce well above the anticipated harvest weight of 180g, indicating their suitability for crop production in urban warehouse settings. The findings of this experiment contribute valuable insights into the feasibility of utilizing various types of wastewater for hydroponic crop growth. Future experiments employing GREENBOX technology may utilize these findings to enhance the efficiency, productivity, and sustainability of GREENBOX units. This study has impactful implications for sustainability, as it offers a potential solution to mitigate water scarcity and promote efficient resource utilization in agricultural practices. Keywords: CEA, Hydroponics, lettuce, Reclaimed Wastewater, urban agriculture

Plugs are crucial for starting crop production in greenhouses, soil, and controlled environment agriculture (CEA). Horticultural, vegetable, fruiting, and ornamental crops that utilize plugs for production have demonstrated better plant health, transplant establishment rate, and total yield. Many substances are capable of supporting plug growth, so the APS Laboratory for Sustainable Food at Florida Gulf Coast University investigated the quality of plugs prepared based on different commonly used growth mediums for plug production. We carried out the growth of Rex Butterhead Lettuce Latuca Sativa plugs with six different treatments: 1) Rockwool, 2) Oasis® Horticube, 3) Perlite 4) Coco Coir, 5) Phenolic Foam, and 6) Peat Pellets. The seeds were sowed in their respective growth medium and watered every day. The plugs were then cultivated for 15 days in a controlled environment until two leaves apart from the cotyledon had developed. After 15 days, we collected data which included wet weight (g), dry weight (g), leaf area (cm2), nitrogen content (mg/g), and chlorophyll concentration (mg/cm2). In addition, we derived data including the Leaf Area Index (LAI) and Specific Leaf Area (SLA, cm2/g). Descriptive statistics were used to describe the biomass data. Pairwise permanovas were conducted, followed by pairwise Wilcoxon tests to determine which treatments result in significant differences for each response variable. A permutation MANOVA revealed a significant treatment effect on plug preparation (p=0.001). All subsequent multilevel pairwise comparisons were significant, with the exception of phenolic foam vs perlite (p=0.294). Of all the treatments, we concluded that plugs grown in Peat Pellets produced the most viable plugs with the largest wet weight (g), dry weight (g), and total leaf area (cm2). Results from this study may inform growers about appropriate growth mediums for efficient plug production. Keywords: Controlled Environments, Growth Mediums, Lettuce, Plugs, Urban Agriculture

 Conventional agricultural techniques have been degrading American soils nationwide since the beginnings of modern-day agriculture through practices such as soil tilling, using nitrogen synthetic fertilizers, and monocultural systems. These previously mentioned techniques contribute to degrading soil health, mass emissions of carbon dioxide into the atmosphere, and decreased biodiversity. Regenerative agriculture offers a combination of sustainable practices that will create carbon sinks to sequester atmospheric carbon dioxide, restore national food systems, and prioritize soil health. Regenerative agriculture techniques include the utilization of cover crops, compost, no-tillage, mob grazing, and polyculture. The APS Laboratory for Sustainable Agriculture focused on the effectiveness of compost by comparing the growth of lettuce in four different treatments: 100% compost (100%C), 75% compost 25% Miracle-Gro (75%C-25%MG), 50% compost 50% Miracle-Gro (50%C-50%MG), and finally, 100% Miracle-Gro (100%MG). The lettuce seeds were kept in a growth tent for 15 days during their period of germination before being transferred to four 1x1 meter plots in the Food Forest at Florida Gulf Coast University (FGCU) for the 60-day growth period. The lettuce crops grew to full bloom and ready for harvest. Sampling events took place every six days in which crop growth data including wet weight (g), dry weight (g), chlorophyll concentration (μmol/m^2), and leaf area (cm^2) were collected. Specific Leaf Area (g/cm^2) and Leaf Area Index were derived, and statistical analysis was conducted. Based on the statistical tests conducted at the 5% significance level using R statistical software, soil treatment type was found to be significant (p=0.0002). Soil treatment type was shown to have significantly impacted wet weight (p<0.0001), dry weight (p<0.0001), and leaf area (p=0.0011), but not nitrogen (χ^2 [3]=3.91, p=0.2717). Results demonstrate the effectiveness and feasibility of using compost as a technique for regenerative agriculture.

The integration of sustainable technologies in waste management systems has become imperative in addressing the escalating challenges of agricultural productivity and sustainability. Plugs are essential when starting crop production in controlled environment agriculture (CEA) setups and greenhouses. Horticultural crops such as vegetables, fruiting, and ornamental plants that utilize plugs have demonstrated higher success rates, healthier plants, and higher total yields. The APS Laboratory for Sustainable Agriculture at explored the innovative utilization of digestate from the Home Water-Energy-Food Systems (H-WEF), the H-WEF system converts household food waste into biogas, electricity, and nutrient-rich digestate. The digestate from the H-WEF system was used to produce agricultural plugs, presenting a novel approach to circular resource utilization. We carried out the growth of Rex Butterhead Lettuce Latuca Sativa plugs with eight different treatments, 1) control synthetic fertilizer; 2) 5% Digestate – 95% RO Water (5D–95RO); 3) 10% Digestate – 90% RO Water (10D–90RO); 4) 15% Digestate – 85% RO Water (15D–85RO); 5) 20% Digestate – 80% RO Water (20D–80RO); 6) 25% Digestate – 75% RO Water (25D–75RO); 7) 30% Digestate – 70% RO Water (30D–70RO); 8) 35% Digestate – 65% RO Water (35D–65RO). The seeds were sowed with their fertigation treatment and watered every day. The plugs were cultivated for 15 days in a controlled environment until two leaves had developed after the cotyledon. After 15 days, we collected data on wet weight (g), plug head area (cm2), total leaf area (cm2), total nitrogen content (mg/g), total chlorophyll content (mg/cm2), and dry weight (g). In addition, we collected data on the Leaf Area Index (LAI, cm2/cm2) and Specific Leaf Area (SLA, cm2/g). The synthetic fertigation yielded a higher wet weight than the following treatments: 5D–95RO, 10D–90RO, and 35D–65RO. While the 30D–70RO treatment produced a larger plug head than all other treatments. The digestate-based fertilizers were comparable to the synthetic fertilizer at dilutions of 25D–75RO and 30D–70RO. Results from this study may inform growers about the viability of utilizing digestate for plug production.

Anticipating crop advancement, particularly fruit maturation, is critical for peach growers' success and marketing. Growing Degree Days (GDD) predict the growth and development stages of plants and insects. They are based on the accumulation of heat units above a specific baseline temperature, under the concept that a certain amount of heat is needed to develop from one stage to another in the life cycle. GDDs are used for various purposes in agriculture and horticulture, such as planting scheduling, pest management and crop monitoring. Peach growers use GDD to predict the peach cultivar maturity and schedule harvesting. However, peach cultivars' ripening time is reported in the calendar or Julian days (JD) or as the number of days before or after a reference cultivar, which is not amenable to climate change. Therefore, we modeled GDD in a diverse set of peach and nectarine cultivars and breeding accessions using the Baskerville-Emin (BE) method. The GDD was calculated from full bloom to fruit maturity using historical temperature, bloom and ripening data collected at the Musser Fruit Research Station in Seneca, South Carolina, in the 2017-2023 period. GDD and JD variability will be presented, and implication of providing GDD information on existing and newly released cultivars for producers and researchers will be discussed.

This study addresses the critical need for precise irrigation management in the greenhouse production of high-value ornamental crops, focusing on the propagation of single-stem rose (Rosa rubiginosa) cuttings under light-emitting diode (LED) supplemental lighting. The current lack of effective monitoring and control systems for substrate moisture poses challenges in optimizing plant growth while minimizing water and nutrient losses. In this context, we propose the integration of moisture sensors for real-time monitoring and control of substrate moisture levels, coupled with LED supplemental lighting, to enhance the production of rose cuttings. Our approach involved assessing the feasibility and effectiveness of moisture sensor-controlled irrigation in greenhouses, considering the specific requirements of rose propagation and the influence of LED lighting on plant growth. We tested three Ө thresholds (0.25, 0.35, and 0.45 m3.m-3) and five light levels as supplemental lighting (100, 175, 250, 325, and 400 µmol.m-2.s-1) arranged on randomized complete block design with four replications. Rose Double Knock Out® ‘Radtko’ PP 16,202 CPBR 3,104 plants were grown in 15.6 L pots (Pioneer Pots; Blackmore Co., Belleville, MI) filled with 20% Canadian peat/58% aged pine/10% perlite/12% EZ Hydrafiber lime potting mix (Oldcastle HFC25; Oldcastle Lawn

Exponential population growth adds increasing pressure on the agriculture industry to grow and distribute fresh foods to rural and urban areas, leading to the development of GREENBOX technology, which utilizes Controlled Environment Agriculture (CEA) principles to optimize the desired conditions for growth of leafy green crops. Using commercially available equipment, GREENBOX technology has the capability to be integrated into existing urban infrastructure to help relieve the negative impact urbanization has on the availability of fresh foods. GREENBOX technology allows environmental variables, such as temperature, humidity, light intensity/ spectrum, and nutrient delivery, to be controlled to enhance the growth performance of leafy greens. Precursory experiments using GREENBOX Technology utilized the standard photoperiod of 16 hours of light, and 8 hours of dark for all crop production. The main objective of this study was to conduct a comparative analysis of Lactuca sativa Rex Butterhead Lettuce production grown under different photoperiods using GREENBOX technology. Using the standard 16 hours of light and 8 hours of dark as the control, two different photoperiod treatments were tested. Treatment one consisted of a 14-hour light period and a 10-hour dark period, while treatment two consisted of a 12-hour light period and a 12-hour dark period. The biomass and productivity of the crops were measured in addition to the environmental conditions for each lighting regimen to ascertain any significant differences. The biomass parameters included wet weight (g), dry weight (g), leaf area (cm2), leaf count (n), and chlorophyll concentration (mg/cm2). We derived additional data, including the Leaf Area Index (LAI, cm2/cm2), Specific Leaf Area (SLA, cm2/g), and biomass productivity (kg/m2). A statistical analysis of the biomass data was used to understand the differences in biomass parameters between crop growth and different light lengths. No statistically significant differences were found between the biomass and productivity parameters for the 12-hour and 14-hour photoperiods. However, the weight weights, dry weights, Leaf Count, SLA, and LAI from the 16-hour photoperiod showed statistically significant differences from the 12 and 14-hour photoperiods. All treatments still produced Rex Butterhead lettuce above the expected harvest weight of 180g and are viable for crop production in urban warehouse settings. The results of this experiment may help us understand the relationship between photoperiod and the biomass performance of leafy greens. Future GREENBOX experiments may use this information to increase the efficiency and productivity outputs of GREENBOX units. Keywords: CEA, Hydroponics, lettuce, soilless agriculture, urban agriculture

Enhancing Germination of Silver Saw Palmetto (Serenoa repens form glauca): Water Uptake, Temperature, and Pre Sowing Treatment Effects - Vania Pereira
Propagation Strategies and Epigenetic Variations in Vaccinium Berry Crops - Samir Debnath
The Application Timing of a Cytokinin B-Mo-based Product Affects the Growth and Non-Structural Carbohydrates Contents of Cuttings During Adventitious Root Development - Mayra Toro Herrera
Characterizing the effects of PPFD and VPD during indoor acclimation of Chrysanthemum cuttings - Ana Sofia Gomez
Asexual Propagation of Salix humilis Using Dormant Hardwood Cuttings After Stock Plant Coppicing and Fungicide Application - Hazel Schrader
Evaluation of Auxin Application and the Presence or Absence of Roots or Inflorescences in the Propagation of Variegated Carex wahuensis subsp. wahuensis - Paulo Matos
Evaluating the Effect of Plant Growth Hormone Types and Rates on Osmanthus spp. Propagation - Yulong Chen
Evaluating Leaf Cutting Success for Achimenes Propagation - Chad T. Miller

Silver saw palmetto is a native palm of the southeast coast of the United States that is of high ornamental value for native landscapes and commercial potential production due to its fruit’s phytotherapeutic properties. The main propagation method for this palm is seed-based germination, which has very slow and low germination rates. This study assessed imbibition rates, germination in different temperatures that simulated Florida seasons, and pre-sowing treatments. Diaspores were exposed to seeds within the endocarp, intact seeds, scarified seeds, and seeds with their operculum removed. The maximum fresh weight of saw palmetto seeds after imbibition was observed at 11 days. Significant differences in imbibition rates and final weight were noted for seeds with an endocarp, with lower fresh mass, and scarified seeds, which showed the highest rates. Summer temperatures consistently yielded the highest final germination percentage and uniformity for seeds with or without an endocarp on constant summer temperatures or move-along experiments throughout Florida seasons. Pre-sowing treatments, such as the removal of the operculum, proved to be highly efficient in promoting the highest germination percentages and rates, while seeds with an endocarp demonstrated lower and uneven germination. The application of hormones, particularly GA3 at 10,000 ppm, also showed promise in improving germination rates.

Blueberry (Vaccinium sect. Cyanococcus Rydb.), lingonberry (V. vitis-idaea L.) and huckleberry (V. membranaceum; also called black huckleberry or black blueberry) are three important Vaccinium small fruit crops native to the North. They are valuable resources for bioactive components that play important roles in anti-oxidant, anti-tumor, anti-ulcer, and anti-inflammatory activities. They can be propagated to produce true-to-type plants either conventionally or by micropropagation. Propagation in vitro is now well accepted worldwide for commercial production of Vaccinium crops. Proficient plant propagation technique using shoot organogenesis and somatic embryogenesis was successfully established in blueberry and lingonberry. Shoot regeneration and proliferation in in-vitro conditions using various liquid bioreactors have successfully been achieved in various Vaccinium species. One of the major concerns in commercial production is the occurrence of variation in micropropagated plants. This presentation describes the in-depth progress of genetic and epigenetic variations in different Vaccinium species during micropropagation. It addresses different molecular techniques used to monitor true-to-type and epigenetics along with application of epigenetic variation in micropropagated Vaccinium berry crops. Keywords: blueberry, bioreactor micropropagation, DNA-methylation, huckleberry, molecular markers, lingonberry, somaclonal variation

A large group of horticulture species are propagated vegetatively through shoot-tip cuttings harvested from stock plants and planted to form adventitious roots. Adventitious root development (ARD) leads to establishing a carbohydrate sink in the region of root regeneration, which is highly dependent on energy and carbon skeletons. We hypothesized that enhancing the source-to-sink relationship during ARD can lead to an efficient carbon allocation to growth, resulting in a well-rooted cutting. Thus, the research aimed to determine if the application time of a Cytokinin B-Mo-based product during the ARD of unrooted cuttings would impact the source-to-sink relationship and, hence, affect plug growth and quality. The product was applied at four application times plus a negative control as follows: T1: plants without product (control), T2: sticking stage (starting 24 h after the sticking); T3: callus formation stage; T4: root development stage; and T5: toning stage. The experiment was a complete randomized design with five treatments and 60 repetitions for treatment (n=60) in two experimental runs (n=120). The root and shoot length, the number of leaves, the leaf chlorophyll content, the root and shoot dry matter, and the root-to-shoot ratio were measured. Results indicate that applying the product at T2 in ARD's dedifferentiation and induction phase leads to the shortest root and shoot length, the lowest dry matter accumulation, and some phytotoxicity effects. For T3 in ARD's initiation phase, the application results in greater root, total dry matter, and total soluble sugar contents than the control. For T4 in ARD's expression phase, the application results in greater growth, total dry matter, and sucrose and starch contents than control and other treatments. Applying the product in T5 when the roots had grown and reached all the edges of the growing media did not have any benefit compared to the control. Our results suggest that the exogenous application of a product to strengthen the source-to-sink relationship during adventitious root development can potentially enhance the non-structural carbohydrate contents when applied at the root formation phase (T4), which correlates positively with the increase in the length and dry matter of the roots, generating a well-toned rooted cutting.

During acclimation of unrooted cuttings (URC) under mist irrigation, the moisture status of URC is greatly affected by environmental conditions such as high photosynthetic photon flux density (PPFD) and vapor pressure deficit (VPD), both of which can cause rapid dehydration. The objective of this study was to characterize the effects of PPFD and VPD on indoor acclimation of Chrysanthemum ‘Olympia White’ URC. Cuttings were stuck in a peat-perlite substrate in propagation trays, placed under sole-source lighting in chambers where ultrasonic fog was used to automatically control relative humidity (RH). Mist irrigation was applied every 20 to 30 min for 3 h. Over 12 h, URC were exposed to 0, 35, 70, 80, 105, 140, or 210 µmol·m–2·s–1 PPFD and 70, 80, 90, or 100% RH setpoints, resulting in air VPD levels ranging from 0.02 to 0.59 kPa. In the chambers, there was a high level of environmental control, and PPFD did not affect air VPD (P = 0.712), which were therefore considered as independent climatic factors. Leaf temperature minus air temperature was considered an indicator of plant energy balance, where a warmer leaf than air temperature is a driver of evapotranspiration. Plant leaf temperature became cooler than the air temperature as air VPD increased (P = 0.024), likely caused by evaporative cooling of leaves. In contrast, increasing PPFD increased leaf temperature relative to air temperature, likely through radiant heating. Leaf VPD was positively correlated with air VPD (adjusted-R2 = 0.88) but was also affected by the interaction of PPFD and air VPD (P < 0.05). Two hours after misting was terminated (5 h total), some plants showed clear wilting especially under low RH. At 5 h, stomatal conductance and evapotranspiration of URC was increased by PPFD and decreased by air VPD (P < 0.01), although there was an interaction between PPFD and air VPD for stomatal conductance (P < 0.005). Further results highlighting responses to RWC, water uptake, and water loss will be presented.

Prairie willow (Salix humilis) is a naturally compact and adaptable shrub willow native to the eastern United States. This taxon has potential for use in managed landscapes because of its desirable habit, attractive flowers and foliage, and its purported tolerance to fluctuations in soil moisture. This adaptability could be advantageous for urban green infrastructure applications. However, unlike most willows, S. humilis is thought to exhibit recalcitrance to standard asexual propagation techniques. This recalcitrance is exacerbated by observed susceptibility to fungal infections that cause cutting mortality during propagation. Because juvenility can improve the rooting of propagules, we questioned whether stock plant rejuvenation (coppicing) and propagule treatment with fungicide would influence rooting and survival of S. humilis dormant hardwood cuttings. In February 2024, 300 full-length dormant stems were harvested at the USDA Plant Introduction Station in Ames, Iowa from stock plants that were either coppiced or not coppiced the previous year. Uniformly-sized basal cuttings were acquired by removing the proximal 23 cm of each stem. Experimental trials (N=300; n=75) evaluating the full factorial of stock plant status [non-coppiced (-coppice) or coppiced ( coppice)] and fungicide application [non-treated (-fungicide) or treated ( fungicide) by submerging propagules in T-Bird with 46.2% Thiophanate-methyl for 15 minutes] were conducted in a cool greenhouse at the University of Minnesota Horticultural Research Center in Chaska, MN. All cuttings were treated with 0.8% indole-3-butyric acid via Hormodin-3 Talc powder and stuck in 50 cell trays (5 × 5 × 12.5 cm cells) with a 1:1 perlite:bark-based media and placed on heat mats (22ºC) using a completely randomized design. Total number of propagules rooted, length of the longest three roots, and number of roots were recorded. Propagules were ranked on their overall rooting performance using a Likert Scale. Rooting percentage was 77%, 56%, 87%, and 69% for coppice/ fungicide, coppice/-fungicide, -coppice/ fungicide, and -coppice/-fungicide, respectively. Compared to the non-coppiced propagules, mean count of roots decreased by 41% for coppiced propagules, across fungicide applications. Compared to propagules not treated with fungicide, mean count of roots increased by 19% for propagules treated with fungicide, across coppice treatments. Future research will evaluate different types of cuttings to generate a complete vegetative propagation protocol for Salix humilis. This work supports the introduction of this versatile plant into commercial production, thereby augmenting the ornamental plant palette for challenging urban landscapes.

Carex wahuensis subsp. wahuensis is an endemic Hawaiian species extensively used as a ground cover in landscaping and restoration. In recent years, a variegated form was identified and is now starting to be utilized in a handful of landscaping projects. While the green wild-type has been primarily propagated through seeds, protocols for single plant divisions are lacking and limits the commercialization and availability of the variegated form. In this study, we investigated the effect of indole-3-butyric acid (IBA) application as well as the presence or absence of roots and inflorescences on propagating single plant divisions of variegated C. wahuensis subsp. wahuensis. Container grown clumps were divided into single plantlets, with or without flowers and with or without roots (trimmed 7.6 to 10.2 cm length). For the first experiment, plantlets without flowers but with pre-existing roots were treated with or without 3000 ppm IBA and planted in 1:1 perlite and vermiculite. For the second experiment, plants with roots but with or without flowers, and plants without roots and flowers were also planted in 1:1 perlite and vermiculite. Both experiments were located on a mist bench, which activated every 2 minutes for 12 seconds, and both were allowed to root for up to 135 days. Root length and rooting index was recorded for the first experiment at 45 and 90 days after planting while rooting index was recorded for the second experiment at 45, 90 and 135 days after planting. Application of IBA did not improve root length and rooting index of plantlets. However, there was an observed difference in root length and rooting index between experimental runs. In the second experiment, plants with roots and no flowers exhibited the highest rooting index (3.3 = light rooting) followed by plants with no flowers and no roots (2.9 = alive but no roots to light rooting). Plants with flowers and roots exhibited the lowest rooting index (1.7 = mostly dead). Results of the study indicate that vegetative single plantlets of variegated Carex wahuensis subsp. wahuensis can be successfully rooted within 135 days after planting under mist.

Osmanthus is a genus of ornamental plants with valuable qualities such as pest resistance, evergreen foliage, and aromatic flowers. However, different species respond differently to growth hormones for propagation. This study aimed to evaluate the types and rates of plant growth hormones on different species of Osmanthus propagation. Six distinct Osmanthus species (Osmanthus heterophyllus ‘Kaori Hime’, Osmanthus armatus ‘Jim Porter’, Osmanthus x fortunei ‘Patty's Secret’, Osmanthus heterophyllus ‘Rotundifolius’, Osmanthus delavayi, and Osmanthus x fortunei ‘Fruitlandii’) were treated with Indole-3-butyric acid (IBA) powder, 500 mg/L and 2000 mg/L of Potassium Indole-3-butyric acid (K-IBA), 10% Kelpak (seaweed extract), and water dip (the control). The cuttings’ survival rates, rooting rates, callus rate and area, and root length were recorded. The results showed the O. heterophyllus ‘Kaori Hime’ exhibited the best survival and rooting rates, while the O. heterophyllus ‘Rotundifolius’ had the lowest survival rate, the O. armatus ‘Jim Porter’ had the highest callus quantity. Plants treated with IBA powder had significantly larger callus area than those seaweed treatments. In conclusion, O. x fortunei 'Fruitlandii' and O. heterophyllus 'Kaori Hime' exhibit superior performance in all six measurements compared to other plant species and are highly recommended. Conversely, O. delavayi and O. heterophyllus 'Rotundifolius' have displayed considerably weaker performance and are not recommended. Further research is necessary to determine the effectiveness of other propagation methods and treatments for Osmanthus.

Advances in Phytophthora, Pythium, and Phytopythium Species Detection, Isolation, Culture, Diagnostics, and Virulence Rejuvenation -William Errickson
Effect of Planting Date on Strawberry Yield - Samantha Simard
Evaluation of Irrigation Strategies in Watermelons - Juan Enciso

The Lower Rio Grande Valley farmers traditionally irrigate vegetable crops with furrow irrigation systems. To conserve water and mitigate the effects of droughts, there is a need to adopt more efficient irrigation and fertilization methods and practices in vegetable crops to increase crop production quality and profitability. Farmers that use furrow irrigation systems apply from 4 to 6 inches per irrigation depending on their furrow length and apply more than five irrigations during the vegetable growing season, and using between 20 inches (1.7 ac-ft) and 40 inches (3.3 ac-ft) of irrigation water in their fields. Vegetables have a shallow root system, so farmers must irrigate frequently to maintain good moisture levels during the growing season for optimum growth, possibly wasting water. We use image analysis derived from Unmanned Aerial Systems (UAS) and irrigation soil water sensors to provide management recommendations to schedule drip and surface irrigation to conserve additional amounts of water. We established replicated research experiments using subsurface drip irrigation and soil water sensors (watermark sensors) to irrigate watermelons and other vegetable crops. We grew plants under three different water levels to trigger irrigation (50, 75, and 100 cb). A drip irrigation system with plastic mulch was placed in the field, as well as soil-water sensors, to measure and monitor the soil moisture. After calculating the water used in the three water level treatments, the 50 cb treatment used 0.27 ac-ft, the 75 cb treatment used 0.24 cb and 0.22 ac-ft was used by the 100 cb treatment. According to our results, we could conserve up to 3.0 ac-ft with our recommendations. We concluded that watermelons could be managed when the soil-water sensor readings range between 50 and 75 CB and approximately 0.3 ac-ft of water using subsurface drip irrigation. We obtained an average yield of 53,536 lb/ac, when irrigated under the 50 cb treatment, 42,059 lb/ac at 75 cb, and 36,719 lb/ac at 100 cb.

Not only are Phytophthora, Pythium, and interesting Phytopythium species potentially devastating horticultural pathogens, they regularly present challenges in vitro. In this study, multiple established and novel methodologies were built upon to bolster researchers’ ability to quickly isolate, differentiate, and promote virulence of multiple oomycetes principally collected from symptomatic conifers and nearby water sources. These methods allow greater flexibility in generating clean mycelial cultures for genetic characterization, varying pathogen structures for use in novel bioassays (such as synchronized production of sporangia or zoospores), and ultimately inoculations to evaluate oomycide efficacy or make headway towards completion of Koch’s postulates for previously uncharacterized host: pathogen pairings. Phytopythium vexans (Pp. vexans) (n=8 isolates), three Phytophthora species / species complexes including P. cinnamomi (n=10), P. cryptogea / drechsleri complex (n=4) and P. humicola (n=2), as well as 5 tentative species of Pythium, were evaluated. Isolations took two forms, standard root sampling onto Phytophthora selective media (PARPH), or water-based sampling through a modified ‘baiting/trapping’ technique that utilized on-site collected water samples in the laboratory. The ‘baits’ were Cannabis sativa seed, Vigna radiata beans, and Rhododendron maximum leaves suspended in aerated water samples or slurry of silt/soil. Samples were evaluated on V8-agar (V8A), pea agar (PA), pea broth (PB), potato dextrose agar (PDA), cornmeal agar (CMA), and water agar (WA), each of which provided distinct morphological indicators and structures useful in diagnostic guides and in bioassays or inoculations. As is typical with all plant pathogens, the longer they remain in culture, the less virulent they may become. With oomycetes, this is compounded as the pathogen will often go into chlamydospore or oospore formation (long lived survival structures) which are not ideal for experimentation. Inclusion of germinated then surface sterilized (70% ethanol for 30s) Vigna radiata and Lupinus perennis sprouts into recently poured (still liquid) 1/8 clarified V8 juice agar (1/8 clV8A) provided a media capable of rejuvenating the pathogen due to presence of living roots and dynamic plant nutrients. This allows for more predictability of zoospore formation, especially if they are intended to be used with a time sensitive trials. In numerous incidences multiple species of Phytophthora and Phytopythium vexans isolates went into zoospore release simultaneously by utilizing these approaches in combination with resource starvation and culture washing with sterile distilled water. Taken together these approaches will greatly aid any researcher working with root disease oomycetes in culture.

Optimizing planting date for strawberry in California production is a sustainable measure to maximize yield and maintain plant health. The goal of this project is to assess the optimal planting date for two predominant cultivars: 'Monterey' and 'Fronteras'. The trial was conducted in field 25 at Cal Poly, San Luis Obispo. The experimental area consisted of 3 beds, each 53.5 ft. long. Standard 64-inch beds with 4 rows of plants per bed and 3 lines of drip tape were used. Beds were planted at two-week intervals: 26 Oct, 9 Nov, 23 Nov 2022. Each bed was planted with four plots of ‘Monterey’ and four plots of ‘Fronteras’ (20 plants/plot). Plug plants were produced at North Carolina State University’s nursery and shipped overnight to Cal Poly and planted in the field the next day. First harvest was 13 Apr 2023 when the first fully red fruit were observed. Fruit were harvested, counted, and weighed twice weekly. The trial was completed 8 Aug 2023 and replicated in the 2024 growing season.

The aims of the federal initiative Sustainable Agriculture Research and Education (SARE) are multifaceted: 1) Foster responsible management of the nation's natural resources through the dissemination of location-specific, regional, and sustainable agricultural and ranching techniques, 2) Improve the livelihoods of farmers and ranchers, 3) Safeguard the well-being of individuals involved in food and agricultural systems by reducing reliance on harmful substances, 4) Encourage agricultural variety and resilience, and 5) Assess the local economic, social, and environmental impacts of adopting sustainable agricultural practices. To achieve these goals, SARE offers numerous grant opportunities for research projects, catering to farmers, ranchers, non-governmental organizations, and universities. SARE operates across four regions within the United States. New Mexico is in the Western region (WSARE) which is composed of individual state professional development programs in the area’s 13 states and 4 Pacific Island protectorates. In 2023, the NM WSARE Professional Development Program coordinated a Sustainable Agriculture Summit to better prioritize research and training needs in the state. The event was held in Santa Fe, NM, USA on 30 March, with a total of 58 participants in the full-day event. Among them were 32 agriculture professionals and 26 farmers and ranchers. The event consisted of two main sessions, a panel discussion, followed by an open forum. The panel was comprised of past Western SARE grant recipients and individuals who had submitted proposals, they provided overviews of their projects. Following the panel, summit participants engaged in a brainstorming session to identify critical sustainable agriculture project needs for producers in NM, focusing on research and training needs not previously emphasized in past funding. The priority areas identified by the participants were, in order of importance, 1) Irrigation/water use efficiency, 2) Farm economics, direct markets, and direct sales, 3) Non-traditional production, 4) Pest management, 5) Labor aids and technology adaptation, and 6) Generational transfer of farms and ranches. Each of these priorities was clearly outlined, and potential projects were identified accordingly. The outcomes of this summit were communicated to WSARE, the NM Department of Agriculture, and other funding agencies, offering valuable feedback to guide future proposals and funding initiatives in NM.