ASHS 2025 Conference

Some invasive plants are listed as “prohibited for sale” on the Florida Department of Agriculture and Consumer Services Noxious Weed List, however many invasive plants are commercially available. Plant This, Not That: A Guide to Avoiding Invasive Plant Species in Florida is a laminated, ring-bound-flipbook written to provide safe alternatives to commonly sold invasive ornamental plants. Perfect for the resident or professionals visiting or running a nursery or garden center, this relevant resource includes 22 invasive plants that are commonly available for sale along with native or Florida-Friendly alternatives. Over 1,350 copies have been sold or distributed, bringing in $14,234. Concepts from the book have been integrated into classes for landscape professionals, industry nursery owners, master gardeners and the general public. Results from the classes show 1.) 367/376 or 97.6% increased their knowledge about the impact invasive species have in Florida, 2.) 371/373 or 99.4% intend to use the information from the class to choose plants that are not invasive, and 3.) 323/344 or 93.9% of participants felt more confident they could identify invasive plant species. Follow up surveys indicated participants used hand pulling to remove invasives (85% or 51/60), avoided invasives from the book (76% or 45/59) and educated others about invasive species (75% or 44/59). Intentional efforts to widely publicize the usefulness of this guidebook and its impact in extension programming have resulted in 11 articles reaching thousands of people, 2 interviews one on NPR and another on the radio, 3 webpages, one press release published on behalf of ASHS, and one journal article in the Journal of Hort Technology.

Horseweed (Conyza canadensis) is a prevalent weed species that has garnered significant attention due to its increasing resistance to multiple herbicides. Glufosinate, a widely utilized herbicide, is among the agents employed for its control. This study investigated the causes and impacts of glufosinate-induced oxidative stress in horseweed. During the flowering stage, glufosinate ammonium (GA) was applied at recommended concentrations. The plants were cultivated in a controlled greenhouse environment maintained at day/night temperatures of 27/25°C, with a 16-hour photoperiod and 75% relative humidity. Morphological symptoms, including curling and burning of leaf tips, were observed within 24 hours of GA application. Elevated levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), and superoxide dismutase (SOD) were detected four hours post-application and persisted for 48 hours. In contrast, activities of catalase (CAT) and ascorbate peroxidase (APOX) were reduced. Notably, guaiacol peroxidase (GPOD) activity increased in GA-treated horseweed leaves. Senescence of leaves and flower inflorescences was evident five days post-application. This study enhances the understanding of glufosinate-induced oxidative stress in horseweed, elucidating the plant's biochemical and molecular responses. The findings contribute valuable insights for improving weed management strategies and promoting agricultural sustainability.

Non-target-site herbicide resistance was evaluated in commercially available herbicides labeled for the management of Palmer Amaranth (Amaranthus palmeri). Seven treatments (T1: Control, T2: Flexstar (22.1%), T3: Buccaneer 5 Extra (53.8%), T4: Flexstar (5.88%) GT3.5 with Glyphosate (22.40%), T5: Defy LV-6 (88.4%): 2,4-D, T6: Enlist Duo (Glyphosate: 22.1% 2,4-D: 24.4%), and T7: Dicamba were applied at recommended rates. Glutathione-S-Transferase (GST) and Glutathione Reductase (GR) activities were measured in leaf samples after 15 minutes of herbicide exposure. Glyphosate exhibited the highest GST activity, followed by Fomesafen > Fomesafen Glyphosate > 2,4-D > Dicamba > 2,4-D Glyphosate. Treatments with a single mode of action exhibited higher GST activity, while mixed-mode treatments showed lower GST levels. Interestingly, an inverse relationship between GST and GR activity was observed, suggesting a compensatory mechanism. When GST activity was low, GR activity increased, indicating that the plant may enhance glutathione regeneration through GR to sustain detoxification capacity and manage oxidative stress. This biochemical compensation could enable the plant to survive herbicide exposure, even when direct detoxification (via GST) is limited. Such adaptability might contribute to the gradual development of non-target-site resistance, as the plant's defense system finds alternative pathways to mitigate herbicidal damage. These findings highlight that herbicide with a single mode of action, which trigger higher GST activity, may accelerate resistance evolution. In contrast, mixed-mode herbicides, which induce lower GST activity and potentially limit compensatory responses, can slow the progression of resistance. Thus, diversified herbicide strategies are essential for sustainable and effective management of Palmer Amaranth.

WORKSHOP OBJECTIVES
The primary goal of this workshop is to bring together a diverse network of professionals from academia, industry, extension services, and government agencies who are working to enhance the performance, sustainability, and resilience of Latin American horticultural supply chains to the U.S.
Participants will:

• Share knowledge on how to improve quality, minimize postharvest losses, and meet regulatory and market demands.
• Highlight opportunities for supporting Latin American growers, exporters, and logistics providers.
• Explore cross-cutting themes including climate resilience, labor, sustainability, and technology adoption.
• Foster collaboration and lay the groundwork for future events focused on Latin America and horticulture.

Speakers:

• Jorge Vanegas – jvenegas@pairwise.com
• Juan Rodriguez – jc@foginfo.org

WORKSHOP FORMAT
I. Expert Presentations (35 minutes total)
 Three panelists (15 minutes each) will present on the following themes:

• Production and Sustainability: Emerging challenges and innovations in Latin American fruit, vegetable, and ornamental production systems.
• Postharvest and Quality Management: Best practices to preserve quality and extend shelf life during export, focusing on compliance with U.S. standards.
• Trade and Market Access: Navigating U.S. regulations, phytosanitary requirements, and certification systems, with insights into logistics and cold chain management.

II. Experience Sharing from the Field (15 minutes)
 A moderated session where 5–6 attendees will briefly (2–3 minutes each) share their field experiences working in or with Latin American horticultural systems. This segment will offer valuable context and grassroots perspectives to enrich the subsequent discussions.
III. Breakout Group Discussions (25 minutes)
 Participants will join focused roundtables based on key crops or sectors (e.g., tropical fruits, temperate fruits, vegetables, ornamentals). Each group will explore:

• Specific supply chain challenges
• Opportunities for innovation and collaboration
• Regional production and trade differences

IV. Group Reporting & Strategy Sharing (15 minutes)
 Groups will reconvene to summarize key insights and report out barriers and proposed solutions (e.g., cold chain infrastructure gaps, pest and disease pressures, labor constraints, traceability needs). A shared whiteboard will capture these points to inform follow-up actions.

V. Building Toward Future Collaboration (15 minutes)
 The workshop will conclude with an open discussion to identify opportunities for future collaboration. This may include organizing a follow-up workshop or proposing a broader symposium or conference focused on Latin American Horticulture—bringing together academic, industry, and government stakeholders to build long-term partnerships and shared research agendas.

Snow peas (Pisum sativum) are a flavorful crop that can be eaten raw or cooked. Diversified farmers often grow them to provide diverse crops for local markets. Controlled environment agriculture allows for fresh harvest and sale in markets that may not otherwise have access to them, such as early or late in the season. This research aims to increase crop diversity for growers. In this research, three cultivars of snow pea were grown including, Oregon Giant, Royal Snow, and Golden Sweet. These varieties were grown using a high (200 mg/L N) or low rate (100 mg/L N) of fertilizer in three different systems. The systems were drip irrigated 3:1 coconut coir: parboiled rice husks, drip irrigated 3:1 sphagnum peat: parboiled rice husks, and hydroponic nutrient film technique (NFT). The pods were harvested every two days for two weeks. Data collected included germination rate, number and weight of pods, and dry weight of shoot biomass per experimental unit. Two trials occurred, the first in winter 2024-2025 and the second in spring 2025. Golden Sweet and Royal Snow had the highest germination rate at over 80% in both trials and Oregon Giant performed poorly at less than 60%. In total harvestable yield, there was no significance in rate of fertilizer by itself, but the interaction between system and fertilizer was significant. In NFT, plants produced more peas with a high rate of fertilizer while in sphagnum peat, they produced more peas with a low rate of fertilizer. Regardless of fertilizer, plants in coconut coir produced very little and experienced a high rate of fruit abortion. In the interaction between system and cultivar, Golden Sweet in NFT produced more than any other combination. In this comparison, when grown in coconut coir, all three cultivars produced significantly less than all other combinations. The production cycle from seed to final harvest was approximately 80 days in both trials. It is feasible to produce a marketable crop of snow peas in controlled environment agriculture. NFT systems with 200 mg/L N of fertilizer produced the highest yield and biomass and could offer hydroponic growers a new crop option.

Maximizing crop yield is essential for the economic viability of indoor vertical farming, where operational costs are high. Among the many factors influencing productivity, planting density stands out as a manageable and cost-effective variable. Optimizing planting density offers a practical approach to improving yields without requiring major structural or technological changes. In this study, we evaluated the effects of planting density on lettuce (Lactuca sativa) yield and individual plant growth characteristics. Two cultivars with contrasting growth habits were used: butterhead lettuce ‘Rex’, known for its compact form, and green leaf lettuce ‘Fusion’, which exhibits an upright growth habit. Plants were cultivated for 24 days after transplanting in a controlled indoor environment maintained at 22 °C, under a photosynthetic photon flux density of 200 μmol∙m-2∙s-1 with an 18-hour photoperiod. Using a deep-water culture hydroponic system, we tested five planting densities: 21, 42, 82, 109 and 131 plants∙m-2. The nutrient solution was prepared with deionized water and a water-soluble fertilizer (12N–1.75P–13.3K; Jack’s Nutrients FeED 12–4–16 RO), providing 150 mg∙L⁻¹ of nitrogen. As planting density increased from 21 to 131 plants∙m-2, total shoot fresh mass per unit growing area rose from 1.6 to 7.2 kg∙m-2 in ‘Rex’ and from 2.6 to 10.9 kg∙m⁻² in ‘Fusion’. However, in ‘Fusion’, increasing density led to a 29% reduction in plant diameter, 19% in leaf number, 25% in leaf area, 33% in shoot fresh mass, and 5% in root fresh mass. Similarly, in ‘Rex’, leaf area and shoot fresh mass decreased by 23% and 26%, respectively, while root fresh mass, plant diameter and leaf number remained relatively consistent across densities. Our results suggest that while increasing planting density from 21 to 131 plants∙m-2 reduces individual plant growth, it increases overall lettuce crop yield per growing area in indoor lettuce production.

Efficient nutrient management is critical for optimizing hydroponic production. However, limited research exists on optimizing nutrient solution volume for various leafy green vegetables in recirculating hydroponic cultivation. To address this gap, we evaluated the growth and nutrient responses of four leafy green vegetables: butterhead lettuce (Lactuca sativa ‘Salanova Red Butter’), arugula (Eruca sativa ‘Standard’), kale (Brassica oleracea ‘Red Russian’), and red Malabar spinach (Basella alba ‘Rubra’). These crops were grown in a nutrient film technique (NFT) hydroponic system under two nutrient solution volumes, Low (76 liters) and High (151 liters), in a greenhouse during both summer and fall. Electrical conductivity (EC) of 1.8 mS/cm was maintained across treatments. Results indicated that leaf nitrogen (N) and potassium (K) content significantly increased with High nutrient solution volume while phosphorous (P) and K followed a similar trend in the fall. Low nutrient solution volume reduced nitrate levels in arugula tissue during both seasons, suggesting that lower volume may help minimize excessive nitrate levels in plant tissues. In summer, nitrate levels in red Malabar spinach (Low volume) and red butter lettuce (High volume) slightly exceeded recommended limits, while kale consistently surpassed safe nitrate levels regardless of treatment. Additionally, nutrient solution volume influenced key postharvest attributes such as color, texture, vitamin C, and anthocyanin content, with species-specific responses. These findings highlight the importance of crop-specific nutrient solution management to optimize plant health, improve nutrient use efficiency, minimize nitrate accumulation and nutrient waste, and support sustainable hydroponic production.

Adequate aeration in deep-water culture (DWC) sustains high dissolved oxygen (DO) levels, promoting nutrient uptake and root development. In multi-layered DWC systems, where a single reservoir supplies multiple trays, strategic aeration placement is essential for uniform oxygen distribution. This study examines how aeration location (reservoir vs. growing tray) and oxygenation method (air pump vs. oxygen concentrator) affect root zone DO levels and the growth of arugula (Eruca sativa ‘Astro’) and spinach (Spinacia oleracea ‘Auroch’). Plants were grown for 25 days in an indoor vertical farm at the air temperature of 22 °C under sole-source LED lighting (18-h photoperiod, 215 µmol∙m⁻²∙s⁻¹). Six aeration treatments were applied in a DWC system comprising a reservoir and a growing tray: no aeration (control), air pump aeration (reservoir, tray, or both), and oxygen concentrator aeration (reservoir or tray). The average DO level in the rootzone without aeration was 5.6 ppm. Aeration using the air pump increased DO to 6.0 ppm when placed in the reservoir, 7.3 ppm when placed in the tray, and 7.3 ppm when applied to both the reservoir and the tray. The oxygen concentrator treatment resulted in a higher increase in DO in the root zone, reaching 9.5 ppm when aeration was applied in the reservoir and 19.7 ppm when applied in the growing tray. Regardless of the oxygenation method, aeration in the reservoir had no effect on the growth of arugula or spinach compared to no aeration. Air pump aeration in the growing tray or both locations similarly increased leaf area, shoot fresh mass, and shoot dry mass in both species. In arugula, leaf area, shoot fresh mass, and shoot dry mass increased by 294%, 227%, and 120%, respectively. In spinach, leaf area, shoot fresh mass, and shoot dry mass increased by 184%, 216%, and 100%, respectively. Oxygen concentrator aeration in the growing tray increased leaf area by 217%, shoot fresh mass by 224%, and shoot dry mass by 73% in arugula, while having minimal effects on spinach. Our findings indicate that aerating the growing tray is more effective at increasing DO concentration than aerating the reservoir. Additionally, oxygen concentrators were more efficient than air pumps at elevating DO levels. However, regardless of DO concentration, aeration in the growing tray with the air pump was most effective at promoting growth in both arugula and spinach.

Soybeans play a crucial role in global agriculture, serving as a primary source of protein and oil, which supports food security, livestock feed, and renewable energy worldwide. The growing demand for food and fuel has intensified the need for soybean production, driving research into soybean cultivation in controlled environments. Manipulating light conditions using specialized LED lights in soybean production is particularly promising, as soybeans are highly responsive to light variations, including changes in the light spectrum. Our objective was to develop compact soybean plants optimized for controlled environments and enhance seed yield by exposing them to various light spectra. Soybean plants (varieties CZ 75 70LL and S16-14801C) were cultivated from seeds in growth chambers (27 °C/26 °C, day/night; 68% relative humidity; 590 µmol mol⁻1 CO₂) in 11 L plastic pots containing peat-moss substrate. One week after germination, the plants were exposed to one of four light spectrum treatments with 700 μmol m−2 s−1 photon flux density. These treatments had different percentages of photon flux ratios of blue (B: 400–500 nm), green (G: 500–600 nm), red (R: 600–700 nm), and far-red (FR: 700–750 nm) wavelengths: 1) 22B:50G:26R:2FR (White light), 2) 20B:80R, 3) 50B:50R, and 4) 40B:40R:20FR. Seed yield evaluations showed that the 40B:40R:20FR treatment resulted in a 10% higher 100-seed weight compared with the other treatments for both varieties. The number of seeds per plant increased by 21% in S16-14801C and 11% in CZ 75 70LL under the same treatment. Seed weight per plant was also higher in both varieties under this treatment, with increases of 26% for S16-14801C and 19% for CZ 75 70LL. Morphological evaluations revealed that the shortest plants were in the 50B:50R treatment, with a 2.4-fold reduction in height for S16-14801C and a 1.7-fold reduction for CZ 75 70LL compared to White light. Plants under the 40B:40R:20FR treatment were 33% shorter than those in the white light treatment for both varieties. Additionally, plants exposed to 40B:40R:20FR had 27% fewer branches but exhibited a 19% thicker stem diameter and a 29% higher shoot dry weight than other treatments. These findings confirm that the light spectrum can be adjusted to meet specific goals and enhance soybean cultivation in controlled environments, particularly by increasing seed yield and promoting plant compactness.

Strawberry (Fragaria × ananassa) production in the United States is a $2.5 billion industry, traditionally dominated by field cultivation. Controlled Environment Agriculture (CEA) is emerging as a promising alternative, offering year-round production and greater control over growing conditions. Despite its potential, strawberry cultivation in CEA systems remains cost-intensive, primarily due to high labor requirements. Additionally, strawberry production follows a cyclical pattern, with fruit developing in discrete peaks known as flushes. These fluctuations present challenges for consistent resource management, labor planning, and market supply, highlighting the need for predictive tools to optimize production efficiency. Our primary research objective is to develop a strawberry growers’ decision support tool for crop management through yield prediction based on flower mapping, a method of describing floral developmental stages through meristem dissection. Using a soilless hanging gutter system designed to mimic a commercial greenhouse production system, we grew a widely used cultivar Albion. The greenhouse maintained average daytime and nighttime air temperatures of 22.5 ± 3.1°C and 18.2 ± 2.8°C, respectively. Daily light integral (DLI) averaged 20.0 ± 3.0 mol·m⁻²·d⁻¹, daytime CO₂ concentration averaged 580 ± 207 ppm, and vapor pressure deficit (VPD) averaged 1.0 ± 0.6 kPa. Supplemental lighting provided a 16-hour photoperiod with a photosynthetic photon flux density (PPFD) of ~250 μmol·m⁻²·s⁻¹. Plants were fertigated through a drip irrigation system and grown in a commercial strawberry substrate composed of 100% coconut coir fiber. We performed weekly flower mapping on randomly sampled plants and yield measurements for the rest of plants for 19 weeks. We hypothesized that yield of a future week can be predicted based on counts of floral buds at each of 11 developmental stages. We found that floral meristem stages 4 and 5 (when calyx and trichomes differentiate on the floral bud) exhibit significant positive correlations with yield occurring nine weeks later. In addition, stage 11 meristems (anthesis) showed a significant positive correlation with yield occurring three weeks later. The remaining developmental stages exhibited weaker correlations and were less reliable predictors of upcoming yield. By using these key developmental stages, we will develop a methodology for forecasting near-future yield. This will help U.S. greenhouse strawberry growers to make informed decisions about resource allocation, labor scheduling, and market planning, ultimately optimizing yield and production efficiency in CEA systems. Our research outcomes lay the groundwork for more comprehensive yield predictions in the future.