ASHS 2025 Conference

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

As US nurseries explore ways to decrease labor costs, mechanization and automation technology (AMT) has become increasingly important. AMTs can help nurseries with repetitive, labor-intensive tasks such as fertilization. Our objective was to compare the Fertileeze Pro-35, an inexpensive fertilizer dispenser (

With costs that can exceed $5,000 per acre, weed management is often one of the largest threats to container nursery profitability due to lack of postemergence herbicide options, need for labor intensive hand weeding, and the demand for weed free ornamentals. Due to high variability in nursery infrastructure, taxa being grown, and grower preferences, no one piece of herbicide application equipment is used at all nurseries in the ornamentals sector. For granular formulations, herbicides are applied with devices ranging from homemade hand-shaker jars, commercially available gravity-flow type hand spreaders, hand-crank hand-held spreaders (i.e. belly grinder spreaders or chest spreaders) and on a larger scale, tractor mounted granular spreaders. Costs for each of these application devices can vary widely and can have a significant impact on the accuracy, distribution pattern, and efficiency of the application, all which effect weed control and labor costs. For example, hand-shakers might be used to treat pots individually to reduce herbicide waste, that is, the herbicide landing outside of the pot during an application. This is a slower process but results in less non-target herbicide loss compared with a belly-grinder in which over 50% of the herbicide applied may not reach the target depending upon pot spacing. The L.E.A.P. (Labor, Efficiency, Automation, Production) team is currently working to evaluate, implement, and develop automation to increase the sustainability of the nursery industry. As part of this work, commonly used and commercially available herbicide application equipment is being evaluated for accuracy, distribution patterns, efficiency, efficacy and crop safety. Prior to initiation of this work, studies were conducted to determine most accurate method of measuring application equipment performance, specifically for granular applicators. Commercially available herbicide pans, plastic and glass plastic beakers, and small plastic funnels (5 cm diameter) with end caps were all tested in multiple different arrangements with 1 to 12 collection devices placed within blocks of nursery containers containing recently potted ornamentals in 3.8 L nursery pots. The use of the plastic funnels placed sunken in the potting substrate was determined to be the most accurate method, in which 82% to 120% of the target dose was captured across all four plant canopies and was the most practical method to implement as it could be used accurately regardless of canopy structure or pot spacing and is ideal for on-farm evaluations. Project was supported by LEAP Nursery Crops Toward Sustainability Award No. 2024-51181-43291.

Native edible berry plants create additional opportunities for native plant growers and nurseries due to their dense nutrient content. However, their growth and physiology under nursery conditions have not been widely studied. Controlled-release fertilizers (CRFs) are commonly used in nursery production, yet their optimal application rates for native edible berry plants remain understudied. While overfertilization can lead to excessive nitrogen (N) leaching, underfertilization can limit plant growth. The objectives of this research were to determine the effects, in a greenhouse, of increased CRF rates ranging from 0 to 0.96 g·L⁻¹ N on the development and physiology of three native edible berry species: Elaeagnus commutata (silverberry), Rhus trilobata (skunkbrush), and Shepherdia argentea (silver buffaloberry). For each species, thirty plants were randomly allocated to receive 15N–3.9P–10K CRF treatments at five different nitrogen concentrations: 0, 0.12, 0.24, 0.48, and 0.96 g·L⁻¹ N. These application rates corresponded to 0%, 25%, 50%, 100%, and 200% of the manufacturer's recommended dose. Throughout the 50-day experimental period, all plants received manual irrigation with tap water. Across all three species, higher CRF application rates led to increased leachate electrical conductivity (EC) and nitrate-nitrogen (NO₃-N) concentrations, as well as enhanced relative plant growth index, total leaf area, leaf dry weight, photosynthesis rate, and stomatal conductance. Lower CRF rates resulted in decreased chlorophyll content, photosystem II efficiency, and leaf nitrogen content in E. commutata and R. trilobata, though root-to-shoot ratios were higher at these lower rates. Physiological parameters such as photosynthesis and stomatal conductance showed no significant increases beyond the 0.12 g·L⁻¹ N CRF rate, while growth parameters remained statistically similar at CRF rates above 0.24 g·L⁻¹ N. This research demonstrates that CRF application rates below the manufacturer's recommendation were sufficient to maintain growth and physiology of the three native edible berry species. Under our experimental conditions, the optimal application rate was determined to be between 0.12 and 0.24 g·L⁻¹ N, which effectively sustained plant growth and physiological responses while minimizing NO₃-N concentrations in leachate. This reduction in fertilizer application could decrease production costs for native plant growers and nurseries, providing both environmental and economic benefits while expanding opportunities in the growing market for nutrient-dense native edible plants.

Advancing restoration and conservation of coastal dune species improves dune ecosystem function by maintaining biodiversity, mitigating habitat degradation, and reducing erosion through stabilization of deteriorating dunes. Galactia microphylla (Littleleaf Milkpea) is a leguminous coastal dune species found in the Florida panhandle which serves as the sole food source for beach mice (Peromyscus polionotus) for more than one month in fall. We conducted a container production experiment to determine the effects of 3 gallon pot type (tall and short) and fertility regimes (Osmocote 15-9-12 plus minors; 3 month formulation) with 1, 2, or 3, 15 g applications applied at a maximum of 15 g per month over 3 months. The experiment was a randomized complete block design with a split-split plot arrangement of treatments restricting randomization with pot type randomly allocated within each block and fertilizer application randomized within each pot type. There were nine single pot subsamples per treatment for a total of 324 pots. Each pot was filled with the same volume of 100% pine bark mulch with fines and planted with 8 (tall pots) or 12 (short pots) heat scarified seed on week 20 (April 16, 2024). Fertilization began week 24 (June 10, 2024) and emergence (%) recorded June 13, 2024. First flower and first fruit (green capsules) were recorded by production week, and mature fruit harvested when brown to evaluate seed production potential. Emergence was 69.3% with no difference between pot types. First flower (Weeks 34–35) and first fruit (Week 36) did not differ among pot types or fertility regimes. Fruit (2 fruits/pot) and seed number (7.6 seed/pot), seed per fruit (1.5) or seeds per plant (1.2) did not differ between the pot types or among the three fertilization regimes. Results suggest bulk container production of Galactia microphylla has potential in both pot types and that flowering, fruiting and seed production are not improved with fertilization regimes providing greater than the standard (30 gram) Osmocote application. Additionally, there was no evidence of a difference in flowering, fruiting, or seed production when fertilization exceeded the standard level of application. Overall, this experiment provides support for bulk container production of Galactia microphylla for tuber production and suggests the lowest quantity of fertilizer tested was sufficient to achieve fruit and seed production.

LEAP is an acronym for investigating the complex nursery specialty crops production system to identify both the individual and interactive effects of Labor, Efficiency, Automation, and Production on current and future nursery industry sustainability. This system is currently experiencing a crisis of labor availability. Our goal is to develop new automation and through better understanding of diffusion of innovation stimulate adoption of existing technologies to study their effects on the remaining system components, including consumer preference at the retail level and the effect of labor retention and re-allocation as a buffer against ongoing labor scarcity. This dynamic approach is necessary, given the complex nature of the nursery specialty crops system that encompasses culturally diverse owner-producer-employee relationships in terms of labor, with high needs for many physically demanding tasks, biological systems, machines, technology, energy, and natural inputs, i.e., water and other resource, all overlaid by preferences and demands of widely different consumer groups. To prevent that labor availability crisis from becoming catastrophic, LEAP and its AB recruited experts at the federal and state level in both plant and social sciences, economics, mechanical engineering, robotics, and artificial intelligence to create five powerful, culturally and disciplinarily diverse teams with expertise in Production and Robotics Engineering (PE), Socioeconomics (SE), Behavioral Adoption (BA), Consumer Preference (CP), and Extension and Science Communication (EX). These teams will work collaboratively with the advisory board, stakeholders, producers, county and regional Extension staff, and allied industries to accelerate the diffusion and impact of automation adoption through nurseries and their workers to illustrate technology’s inherent effect on output, labor efficiency and productivity, revenue, rural economics, and nursery sustainability.

Rose rosette disease (RRD) is a major threat to rose production in nurseries. The causal agent of the disease is a negative strand ssRNA virus called Rose rosette virus (RRV) belonging to the genus Emaravirus. RRD is transmitted by the eriophyid mite Phyllocoptes fructiphilus and grafting. Symptoms of the disease include excessive lateral shoot growth, an abundance of thorns, witches' broom, leaf proliferation, deformed leaves and flowers, mosaic patterns, red pigmentation, and eventually plant death. The aim of this study was to evaluate the effectiveness of novel fungicide treatments, NinjaTM, at various application rates, intervals, and methods in managing RRD. Treatments were applied preventively as a sprench (7-day interval) or drench (14-day interval). Pink Knock Out® rose plants were inoculated with RRD on the same day as fungicide treatments. For inoculation, rose plants were exposed to two mite-infested rose terminals (approximately 4 inches long, with 4-5 leaves), collected from RRD symptomatic shrubs in Rutherford Co., TN. Each plant received about 20 mites. The experiment was arranged in a completely randomized design with ten single-plant replications and conducted twice in a quarantined greenhouse at the Otis L. Floyd Nursery Research Center in McMinnville, TN. At the end of the trials, data on the total number of shoots, number of shoots exhibiting RRD symptoms, open flowers, and phytotoxicity were collected. Two sepals from each plant were randomly selected for mite quantification under a dissecting microscope. The proportion of shoots with RRD was calculated by using the number of affected shoots to the total number of shoots. Rosette severity was rated using a scale of 0-3, where 0= no rosettes, 1= one rosette, 2= two rosettes and 3= three or more rosettes. RRD severity was rated on a scale of 0-3, where 0= no symptoms, 1= one shoot with symptoms, 2= two shoots with symptoms, and 3= three or more shoots with symptoms. Results indicated no significant difference in RRD severity between treated and non-treated control plants. However, plants treated with 11 oz NinjaTM exhibited a significantly lower rosette rating compared to the control plants. Furthermore, both the 8 oz and 11 oz NinjaTM treatments significantly reduced the proportion of shoots with RRD. No significant differences were found in mite count per sepal or open flowers among any of the treated and non-treated control plants. These findings suggest that biochemical pesticide treatment may offer a promising strategy to reduce RRD infection in roses.

The primary form of propagation of ornamental woody nursery liners (young plants) is through stem cuttings to maintain genotypic and phenotypic uniformity. However, high rates of rooting failure in propagation remain a significant challenge, leading to economic loss. Greenhouses offer opportunities to leverage the environment for specific plant growth responses. Manipulation of the daily light integral (DLI) has been used extensively to hasten adventitious rooting and increase propagule quality in annual bedding plants, herbaceous perennials, and culinary herbs. Thus, there is a critical need to also identify the optimal DLI to improve and maximize adventitious rooting in woody taxa. Therefore, this study aimed to quantify the impact of DLI on root growth and development of ornamental woody nursery cuttings. Unrooted stem cuttings of four ornamental nursery taxa were obtained from commercial nurseries and individually inserted into 6.4-cm diameter containers filled with a propagation substrate. Cuttings were placed in a diffused glass-glazed greenhouse under a propagation environment with 20 °C air temperature, 80% relative humidity, and ambient daylight supplemented with ≈120 µmol·m–2·s–1 delivered from light-emitting diode arrays from 0600 to 2200 hr. Cuttings were rooted under fixed 4-mil clear construction film covered with one of four different fixed-woven shade cloths providing ≈72%, 52%, or 30% diffuse shading or no shade (0%). After 14, 28, and 42 d, data was collected including callusing and rooting percentage, root number, longest root length, stem length and caliper, leaf area, and shoot and root dry mass. The results of this study determined the optimal DLI, across an array of important woody taxa, to hasten adventitious rooting and improve liner quality.

Ornamental woody nursery plants are primarily propagated from stem cuttings to maintain genotypic and phenotypic uniformity. However, high rates of rooting failure in propagation remain a significant challenge, leading to economic loss. Greenhouses offer technologies to precisely control the environment. Thus, there is a critical need to identify cost-effective strategies, such as providing root-zone heating, to improve and maximize adventitious rooting. Root-zone heating has been used extensively to hasten adventitious rooting and increase root density in various plant species. However, optimal root-zone temperatures are largely unknown for many woody nursery crops. Therefore, this study aimed to quantify the impact of root-zone temperature on root growth and development of ornamental nursery cuttings. Unrooted stem cuttings of four ornamental nursery taxa were obtained from commercial nurseries. Cuttings of each taxon were individually inserted into 6.4-cm diameter containers filled with a propagation substrate. Cuttings were placed in a glass-glazed greenhouse under a propagation environment with 20 °C air temperature, 80% relative humidity, and ambient daylight supplemented with ≈120 µmol·m–2·s–1 delivered from light-emitting diode arrays from 0600 to 2200 hr. A closed-loop root-zone heating system circulated hot water (49 °C) across greenhouse bench-tops. Forty-eight cuttings of each taxon were placed in root-zone heating environments with set points of 21, 24, 27, 30, and 33°C. After 14, 28, and 42 d, data was collected including callusing and rooting percentage, root number, longest root length, stem length and caliper, leaf area, and shoot and root dry mass. The results of this study determined the extent root-zone temperature can be leveraged to hasten adventitious rooting and improve liner quality.

Tea (Camellia sinensis) was first grown commercially in the Pacific Northwest in Salem, OR in 1988 (Minto Island Growers), and cv. Minto Pacific, selected at that site, was established in a small-scale planting in Burlington, WA in 1997. To test other cultivars for production in the Pacific Northwest region, the successful Washington State University (WSU) vegetative propagation method for ‘Minto Pacific’ was carried out with 14 tea cultivars at WSU Northwestern Washington Research and Extension Center (NWREC): BL1, BL2, Large Leaf, Small Leaf, Christine’s Choice, Dave’s Fav, Sochi, Black Sea, var. Assamica from Mississippi State University; Yukata Midori, Benikaori, Yabukita, Bohea from the USDA National Plant Germplasm System (NPGS) in Hilo, Hawaii; and Minto Pacific from Burlington (year 2 only). For this 2-year greenhouse propagation trial, tea shoots arrived at WSU NWREC on 16 Aug (Mississippi) and 14 Sept 2023 (Hawaii) for year 1, and 16 Sept (Mississippi), 23 Sept (Hawaii) and 25 Sept 2024 (Burlington) for year 2. Both years, shoots were processed into one-node cuttings within 1 day of arrival, the bottom stem of each cutting was scored with a knife, dipped into a rooting hormone for 5-10 seconds, then placed into a treepot filled with a propagation medium (peatmoss, vermiculite, perlite, 5:3:2 ratio). Cuttings were placed in a misting chamber in the greenhouse for 1 year, then moved to a greenhouse bench for 7 months. In February 2024 (Year 1), overall plant survival was 83%, average plant height was 1 cm, plants had 2.5 leaves on average, and the average plant health rating was 4.9/5. Cv. Large Leaf (100%) had the highest survival followed by Dave’s Fave (98%) and Black Sea (98%), while Benikaori (60%) and BL1 (62%) had the lowest survival. In October 2024, the final overall plant survival was 31%, average plant height was 35 cm, plants had 19 leaves on average, and the average plant health rating was 3.6/5. Cv. Christine’s Choice (46%) had the highest survival followed by Large Leaf (43%) and BL2 (42%), while Benikaori (13%) and BL1 (15%) still had the lowest survival. In January 2025 (Year 2), overall plant survival was 73%, average plant height was 2 cm, plants had an average of 1.2 leaves, and average plant health rating was 4.2/5. Cv. Minto Pacific had 100% survival followed by Large Leaf, Christine’s Choice, and Assamica (all 95% survival), while Benikaori (40%) and Sochi (51%) had the lowest survival.

Plants evolved with roots in the soil, providing a temperature buffer to the root zone most of the year. However, as the nursery industry has primarily moved plants out of the ground and into thin plastic containers with very coarse organic substrates, we are faced with added challenges of managing substrate temperature to ensure healthy plant production. Moreover, resource efficiency, particularly regarding mineral nutrients, is a critical factor in the long-term success of the nursery industry. Fertilizer release is controlled by water and temperature in container-grown ornamental nursery production systems. Thus, it was hypothesized that pragmatic management of substrate temperature and moisture could extend the longevity of controlled-release fertilizer in a container system. This study was conducted to determine the effect of irrigation scheduling, container color, and stratified substrates on substrate temperature management, crop health and development, and fertilizer longevity. ‘Limelight’ Hydrangea (Hydrangea paniculata) were grown in either black or white containers and subjected to a single daily irrigation or the same volume applied in three increments throughout the day (cyclic). Hydrangeas grown in white containers with cyclic irrigation increased plant growth by up to 50% compared to those grown in black containers with single-application irrigation, and stratified substrates reduced phosphorus leaching by 30%. Across all treatments, plant health, root development and fertilizer efficiency were improved with substrate temperature management strategies. The results indicate growers should pursue root zone temperature mitigation strategies to enhance crop growth and salability, increase fertilizer use and efficiency, and decrease phosphorus leaching from nursery containers.

Efficient and accurate counting of plants is critical for nursery inventory management to support yield prediction, sales forecasting, and monitoring. Current practices in nurseries depend heavily on manual methods, which are labor-intensive and prone to errors. Researchers have made efforts in utilizing computer vision and deep learning to address these issues, yet a seamless solution for plant counting and inventory management remains unavailable. Image-based counting systems often struggle with classification accuracy in diverse, real-world scenarios, while tracking plants in videos faces challenges such as identity switches, misclassifications, and varying field conditions, limiting the reliability of existing methods. To overcome these challenges, we developed a cloud-based complete solution specifically for ornamental plant nursery inventory management. Our system introduces a novel tracking algorithm KBTrack, optimized for precision and scalability. At its core is an ensemble deep learning model that combines a transfer learning-based YOLOv11 and a CutMix-enhanced YOLOv11 model for plant detection. The KBTrack was developed on top of ByteTrack multi object tracking framework by adding a layer that compares segmentation masks across multiple frames for long term matching of the objects. This addition addressed identity switches and misclassifications, ensuring accurate plant counting even in complex field conditions. The segmentation capabilities of YOLOv11 are also utilized to generate masks for individual plants, enabling customizable plant-specific quality assessments through an interactive dashboard. The system utilizes GPS to allow users to monitor nursery plant beds on a map making it easier to monitor and track changes and updates across the plant beds. The platform is deployed in cloud with a microservice architecture where users can upload field videos and access results through an intuitive interface designed to ensure scalability. To evaluate the capabilities of the proposed framework, data was collected using an autonomous ground vehicle equipped with an OAK-D Pro camera, capturing 4K resolution videos. Experiments conducted on Azalea and Sunshine plants demonstrated the system's effectiveness, achieving a high mAP@50 of 0.982 for detection and 0.981 for instance segmentation on the ensemble model, MOTP 0.916 in the KBTrack multi object tracking algorithm and counting accuracy of 0.988 with an RMSE of 0.669. This confirms its ability to accurately detect and track plants. This solution provides a robust framework for addressing the limitations of current methods, offering an effective and scalable approach to modernize ornamental plant inventory systems.

Hydrangea (Hydrangea macrophylla) is a widely cultivated ornamental nursery crop, but its vigorous shoot growth often necessitates labor-intensive pruning or repeated applications of plant growth regulators (PGRs) to achieve saleable quality. As a result, methods to reduce reliance on pruning or PGRs are highly desirable to growers. One potential alternative is the use of shade netting, which is commonly used in nursery production to protect sensitive plants from excessive solar radiation. This includes hydrangeas which are frequently grown under 30–50% black shade netting. Beyond reducing light intensity, shade nets can also alter the light spectrum, adjusting the relative quantities of blue (400–499 nm), green (500–599 nm), and red (600–699 nm) light, which may affect plant morphology. Blue shade nets, which primarily absorb green and red light, are often marketed as tools to produce more compact shoot growth and thus could serve as an alternative to pruning or PGRs. However, little information exists on the use of blue shade netting to control hydrangea shoot growth. This study evaluated the effects of shade color (black, blue, red, and grey) and blue shade percentage (40–75%) on the growth of hydrangea ‘Twist and Shout’ in a nursery and a greenhouse trial. In the nursery trial, hoop houses were covered with either 30% black, 30% blue, 30% red, or 45% grey shade netting. In the greenhouse trial, chambers were covered with either 40% blue, 50% blue, 75% blue, or 50% black shade netting. Growth parameters including canopy height, width, volume, projected canopy area, leaf length, and chlorophyll concentration were measured repeatedly over a 49-day growth period. Results from the nursery and greenhouse trial showed that shade percentage, not shade color, was the dominant factor influencing shoot growth. Thus, colored shade netting did not suppress plant vigor or reduce the need for pruning or PGRs. These findings suggest that 30% black shade was ideal for hydrangea production, and altering the color of shade netting provided no additive benefits. While ineffective for hydrangea production, nursery crops that benefit from higher percentages of shade such as Hosta plantaginea, may benefit more from colored shade netting.

Nursery and greenhouse growers and dealers in the United States contribute significantly to the economy, environment, and food systems. Nursery and greenhouse operations provide a wide range of plants critical to residential and commercial landscaping, habitat creation for pollinators, and essential planting materials for fruit, vegetable, and ornamental crop production. The sustainability of these operations, as with other agricultural productions, highly relies on water availability, making it significant to evaluate the future of water and climatic risks throughout the United States. This study focuses on the critical part of this evaluation, developing a map of licensed greenhouse and nursery growers and dealers throughout the United States, using information received directly from state officials and agency websites. Texas, Florida and California were revealed to have the most HRI operations (growers and dealers), but the latter two states have the most growers. Region-wise, the Southeast and Northeast regions have the most nursery growers, with the Northern Rockies and Plains and the Southwest regions having the lowest numbers, although states like Utah, Arizona, and Idaho are currently missing in our analysis due to data unavailability and complexity. This mapping exercise will be followed by overlaying climatic indices such as precipitation, temperature and drought forecasts, to evaluate growers' state and regional vulnerability to water and climatic risks. This will aid in assessing climate-related risks, guide adaptive strategies, and support sustainable nursery management across diverse environmental zones.