ASHS 2025 Conference

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.

Parrotia subeaqualis, a recently introduced plant species in the US, exhibits limited genetic diversity due to the limited collection area. Mirroring the declining populations in their native China, limited genetic sampling can impair cultivar development and threaten cultivars' long-term survival. Conservation efforts and providing the initial plant material for breeding programs rely on efficient and dependable propagation methods. This research focuses on developing optimized in vitro establishment and regeneration protocols for various genotypes of Parrotia spp. We conducted experiments to identify the most effective treatment options and media compositions for in vitro initiation and plant regeneration. These experiments explored using different tissue types collected throughout the growing season, basal media, plant growth regulators (PGRs), and other additives. Initial trials with P. subaequalis were unsuccessful due to heavy contamination. Systematically testing different combinations, we determined the specific stimuli required to induce regeneration-competent tissue for diverse Parrotia lineages. Subsequent experiments on P. subaequalis revealed that the most effective media for P. subaequalis was Murashige

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.