ASHS 2024 Conference

A comprehensive analysis of Vidalia Onions transplanting and its impacts - Regimar do Santos
Is Winter Squash a Potential Alternative Cucurbit Vegetable Crop to Combat Whitefly and Whitefly-Transmitted Viruses for Fall Production in Southern Georgia? - Nirmala Acharya
Evaluating Onsite Nitrate and Potassium Sensors - Destany Westlake
Filling the Gaps for Informed Adoption of Carolina Strong Back Grafted Nursery: Transplanting Time and Spacing Optimization - Sukhman Kaur
Substrate Hydro-Physical Properties in Soilless Agriculture: Investigating the Role of Container Geometry on Substrate Air and Water Profiles - Brandan Shur
Kenaf (Hibiscus cannabinus) Compost As An Alternative To Peat - Shawn Steed

Onions are a key crop in the United States. In 2023, 138,000 acres were cultivated in the country with onions. Georgia harvested 11,700 acres in 2023, reaching an average production of 129,000 tons. The onion transplanting process is crucial to the crop cycle and is directly linked to the production potential and quality of the bulbs. Every year, thousands of workers are employed to transplant onion seedlings, which results in a wide variation in operational performance and quality of execution between them. These factors are influenced by the experience and conditions in which the workers operate, which can lead to failures in the process, such as double plants, partially transplanted and plants that have fallen to the ground. Furthermore, manual work is slow and requires many workers, increasing the cost of the operation. Therefore, we aimed with this study to assess the time required to manually transplant onions, the quality of manual transplanting, and the impact of inadequate transplanting on crop development. To assess how much time it takes to transplant an acre of onions, and the quality of transplanting, twenty-five people were observed during their work at a commercial field in Glennville-GA. To assess the impact of poor-quality transplanting, an experiment was carried out in four 10ft replications (10x4ft beds) in Reidsville-GA, simulating four situations observed in the commercial field. Treatments were: T1: 25% of the plants in the plot laying on the ground, T2: 25% partially transplanted, T3: 100% properly transplanted, T4: 25% multiple transplanted, T5: 100% laying on the ground. The difference in operational efficiency between workers exceeded ~20 hours per acre. Results indicated that, in average, one person transplanted 1 acre in approximately 30 hours. The fastest person in the crew transplanted in 22 hours, while the slowest took around 40 hours to transplant 1 acre. Poor-quality transplanting of seedlings exceeded up to 11%. The average number of multiple seedlings was 1%, partially transplanted seedlings was 6%, and laying on the ground was 5.5%. Plant development was assessed based on the number of leaves. Properly transplanted seedlings generated a greater number of leaves compared to the other treatments. Higher leaf number was observed in treatment 3 with an average of 7.33 leaves per plant. All the treatments differed from treatment 5, which had an average of 4.6 leaves per plant. Results indicate that good practices on transplanting can increase onion yield.

The predominant cucurbit vegetable crop during fall in Georgia is summer squash with production value of around $94.08 million on 7,757 acres in 2022 while winter squash acreage was insignificant. Whitefly and whitefly-transmitted viruses (WTV) account for 30-50% summer squash yield losses on average and threaten squash production during fall in the region. Cucurbit leaf crumple virus (CuLCrV), Cucurbit yellow stunting disorder virus (CYSDV) and Cucurbit chlorotic yellows virus (CCYV) are the prominent WTV in southern Georgia. We carried out an experiment during fall 2023 in Tifton, Georgia to evaluate tolerance of winter squash varieties for whitefly and WTV and to study their potentiality for fall production in the region. We compared ten commercial hybrid varieties of which two were acorn types (‘Tay Belle’ and ‘Table Ace’), five were butternut types (‘Waltham’, ‘Ceres’, ‘Atlas’, ‘Ultra HP’ and ‘Genesis’), and one each of a hubbard type (‘Golden Hubbard’), a kabocha type (‘Sweet Mama’) and a calabaza type (‘La Estrella’). We collected data on whitefly number, silver leaf disorder, virus incidence and severity, and fruit yield. In addition, we ran quantitative polymerase chain reaction (qPCR) and quantitative reverse transcription polymerase chain reaction (RT-qPCR) on leaf samples to detect and quantify viruses. There were significant differences between winter squash varieties for whitefly feeding preference, silver leaf disorder, virus severity, virus loads and marketable yield. ‘La Estrella’ had the lowest number of whitefly adults per cm2 leaf area followed by all other butternut types (Genesis, Ultra HP, Waltham, Ceres, Atlas), and highest in ‘Tay Belle’, followed by ‘Table Ace’ and ‘Golden Hubbard’. We found significantly severe leaf silvering in ‘Golden Hubbard’ and ‘Sweet Mama’ followed by acorn types. We observed 100% virus incidence in all the varieties, however severity was lowest for ‘Ceres’, ‘Genesis’, ‘La Estrella’, ‘Sweet Mama’, ‘Ultra HP’ and ‘Waltham’. CCYV loads was found highest in ‘Sweet Mama’ and lowest in ‘Genesis’, ‘La Estrella, ‘Ceres’ and ‘Ultra HP’. CYSDV and CuLCrV loads were highest in ‘Table Ace’ and ‘Tay Belle’ and negligible in other varieties. We observed the highest marketable fruit yield in ‘Ceres’ (7,139 count/acre) and ‘Genesis’ (7,109 count/acre). Although ‘La Estrella’ was less infested with whitefly and WTV, it had poor fruit yields. Overall, we found butternut types mainly ‘Ceres’ and ‘Genesis’ as potential alternative cucurbit vegetable crops for fall production in southern Georgia with lower whitefly and WTV infestation resulting in the highest marketable fruit yields.

Destany Westlake, Paul Fisher, Josh Tebow, and Ryan Dickson Maintaining nutrient balance in hydroponic systems reduces the need to dump nutrient solution, thereby reducing water and fertilizer cost, and the resulting environmental impact. Laboratory testing to monitor nutrient concentrations is reliable, however it typically requires shipment and days to weeks of processing. The objective was to test the accuracy of handheld and inline ion-selective nitrate and potassium sensors compared with laboratory analysis of these nutrients. The methodology consisted of a factorial design with four reservoirs containing two water qualities and two fertilizer recipes with one nutrient film technique (NFT) system per reservoir. Nitrate and potassium concentration was measured twice per week during a 6-week hydroponic trial with basil, using handheld sensors, inline sensors, and Lachat QuickChem 8500 Series 2 analysis by a commercial horticulture laboratory. Based on the laboratory testing, NO3-N ranged from 142 to 272 mg.L-1 and K ranged from 111 to 271 mg.L-1 during the trial. The average error ± one standard deviation for the handheld sensor minus the laboratory concentration was -26.5 ± 18.8 mg.L-1 and -9.4 ± 13.1 mg.L-1 for N and K, and for the inline sensors was 3.5 ± 27.5 mg.L-1 and -15.2 ± 32.1 mg.L-1 for N and K, respectively. Therefore, we conclude that the handheld and inline sensors provided a useful and rapid estimation of N and K levels, but replicated samples should be taken and these levels should be verified by periodic laboratory analysis. Onsite testing could be an important tool for effective nutrient management to reduce nutrient loss and waste.

Grafting is an effective management strategy in watermelon crop against soil borne pathogens. Carolina strongback (SB) rootstock used for grafting, is resistant to both fusarium wilt and root knot nematodes which are devastating soil borne pest of watermelon. In addition, recent studies have shown higher vigour of SB grafted plants than regular nursery plants. However, grafted watermelon nursery is 4-5 times more expensive than regular nursery which leads to reluctance among farmers for adoption of this effective management strategy. Further, recent trials showed that grafted plant bear fruits 7-10 days later than regulate plants leading to farmers losing early profitable watermelon market. To fill these gaps for informed adoption of SB grafted nursery, a field experiment was conducted at Blackville SC with the objective to evaluate the optimum transplanting time and density of SB grafted watermelons nursery to have equivalent fruit yield and harvesting window to that of regular nursery. The experiment comprised of three transplanting times and four transplant densities in a split plot design. We will evaluate the impact of transplanting time and transplanting density on watermelon fruit yield, fruit quality, number of fruits per plant, periodic fruit harvesting yield and plant vigour.

The cultivation of specialty crops in soilless growing systems has emerged as a pivotal practice in modern agriculture. The adoption of container-based production, particularly through soilless culture systems, is witnessing a significant uptrend among specialty crop producers. The challenges associated with cultivating plants in containers are extensively documented, particularly in navigating the delicate balance between insufficient and excess water. Shallow containers often result in excessive water, limiting air availability, while the confined volume of containers imposes restrictions on the water supply for optimal plant growth. Air and water capacity (AWC) model was utilized to determine basic physical properties, such as total porosity (TP), air space (AS), and container capacity (CC), for a substrate in specific-sized and shaped containers. AWC models offer a comprehensive tool for estimating hydrophysical properties across multiple substrate/container combinations simultaneously. The existing literature lacks direct reporting on these specific container types, primarily focusing on modeling the air and water profiles of traditional containers that the floriculture industry utilized, leading to a notable gap in data concerning the dynamic interplay between air and water profiles within these containers and their impact on the rooting environment. 19 substrates and 30 commercially used container selections were modeled to understand their air-water profiles. The results underscore the effect of container geometry on substrate air-water profiles, necessitating different management approaches for the same substrate in different containers. Container height stands out as a critical factor, exerting a substantial influence on substrate characteristics and subsequently affecting air and water values.

Global growing media demand is projected to increase 400% by 2050. Growers are interested in alternative substrates due to the restrictions placed on peat harvesting, as well as transportation and supply chain issues associated with peat. Kenaf (Hibiscus cannabinus), a tropical fibrous plant that was grown and composted in Florida, was evaluated to determine its potential as a horticultural substrate. Research trials were conducted in South Florida to determine effectiveness of kenaf as an alternative substrate for seed germination and plant establishment when compared to a commercially available compost and commonly used growing media. Seed germination trials consisted of planting arugula (Erica sativa) in seed trays filled with either (1) kenaf compost [KC], (2) commercially available compost [CC], or (3) ProMix HP [PM]. Germination was monitored daily, and mean emergence was determined. To evaluate plant establishment, a container trial was conducted using Lantana (Lantana camara) plants that were originally planted in Metro-Mix and transplanted from 1-gallon to 3-gallon plastic containers filled with either KC, CC or PM. Plant visual quality, percent wilt and volumetric water content(VWC) were evaluated weekly and root biomass was determined when plants were deconstructed at the end of the three-month trial. Results show that there were no treatment differences for percent seed emergence of arugula, with all emergence reaching over 80%. Plant establishment in the first field trial found KC and CC treatments increased VWC when compared to PM. Higher visual quality ratings of plants in KC and CC substrates may be explained by the increase in VWC. Lantana plants transplanted and grown in KC were uniform and grew equally as well as CC and better than PM on 13 of 14 rating dates. These data show there is no difference in arugula seed emergence when planted in CC, PM or KC. Lantana establishment in KC was comparable in CC and better than in PM growing media.

Speaker: Dr. Carol Miles, Washington State University
 
Extension Outreach in a Digital World
 
Presentation description: As Extension specialists we carry out applied research and develop new research-based information and deliver it to our clientele in easy-to-understand publications. Today we must deliver our information on-line and though social media, and we track numbers of hits and downloads. How have Extension publication trends changed over the past 20-30 years, including print/online, sales/revenue, promotion/advertising, and what do we see as the future for extension publications. Forming partnerships with extension communication specialists can enable us to focus on information development, where most extension specialists do best, while achieving impacts through information access, which is how we are evaluated.

Advances in Phytophthora, Pythium, and Phytopythium Species Detection, Isolation, Culture, Diagnostics, and Virulence Rejuvenation - Timothy Waller
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 Kentucky Small Fruits Initiative: An Extension-Industry Partnership - Cindy Finneseth
Case Study: Assessing Workforce Training Needs And UMKC Student Interest To Develop Controlled Environment Agriculture Education In Kansas City - Juan Cabrera Garcia
Assisting Florida Sod Producers with Protecting Water Quality by Quantifying Nutrient Inputs and Exports - Bonnie Wells
Will Consumers Purchase a Landscape Scouting Program? - Andrew Jeffers
Native Plant Extension Programming for Commercial Horticulture Professionals - William Errickson

Growers in Kentucky are increasingly interested in adding small fruit crop enterprises to their farming operations. While consumer demand is high, available capital and limited production knowledge are known barriers for small- and mid-scale producers interested in growing and selling these crops. The Kentucky Horticulture Council (KHC) and the University of Kentucky (UK) partnered on a financial and technical assistance support program for Kentucky growers with an interest in producing these crops. Over the 4-year project, more than $936,000 was invested in on-farm projects, working with 275 existing and 76 pre-commercial growers in 89 different counties across the state. Blackberry, blueberry, and strawberry were the highest demand crops. Irrigation, trellising, and netting were the most requested non-plant material inputs. The expected farm impact over the next 10 years will exceed $7.4M, based on yield and sales price estimates. The funding model providing financial assistance to current and prospective growers along with extension’s role in delivering research-based information and providing technical assistance will be discussed. The presentation will also focus on strategies to recruit and screen program participants by assessing needs, setting realistic expectations, increasing production knowledge and skills, with the goal of fostering satisfaction and meeting the intended project objective of increasing small fruit crops profitability for commercial sales over the next decade and beyond.

Controlled environment agriculture (CEA) integrates technology to optimize crop performance. The project goal was to inform the development of CEA curriculum by understanding CEA workforce training needs and gauging student interest at the University of Missouri – Kansas City (UMKC). CEA industry surveys determined the knowledge/skills needed for employment and educational expectations. A second survey was sent to UMKC students to gauge their knowledge of/interest in a CEA educational program. The top five positions in demand by the CEA industry were: (1) manager, (2) worker, (3) research

Adherence to the Florida Department of Agriculture's (FDACS) Best Management Practices (BMP) program is crucial for sod producers to protect water quality. Challenges arise due to perceived low fertilization rates and accelerated production cycles, particularly in South Florida. Challenges are exacerbated by the nutrient export that occurs when harvested sod carries away soil-bound nutrients and residual fertilizer. The sod BMP manual is undergoing revision, with a proposed emphasis on achieving a nutrient balance of nitrogen (N) and phosphorus (P) inputs/exports in sod operations. However, current published data on nutrient export needs to be more comprehensive, necessitating research efforts to fill this knowledge gap. This project, funded by a 2022-2023 FDACS BMP grant, aims to educate and improve sod producer BMPs by assessing current practices and quantifying nutrient inputs/exports through sod slab analysis. A Qualtrics survey was designed to measure sod producers' current BMP practices. Visits to sod farms were employed to collect sod slab samples for nutrient inputs/exports data processing. Results, particularly regarding N and P export, revealed variability across turfgrass species, highlighting the need for further research to determine nutrient sinks and explore the influence of soil depth on nutrient export during harvest. The project's future focus involves providing targeted training based on results to Florida sod producers and exploring additional funding opportunities to address remaining key questions. Results of this project will improve nutrient management inputs/exports budgeting by sod producers and facilitate adoption of practices that improve nutrient management for sod production statewide.

The US landscape industry comprises 632,000 businesses with >1 million employees in 2022. The most common service landscape service providers (LSPs) perform is pest management. Over the past 25 years, consumers have increasingly requested that LSPs use more holistic approaches to pest management, including nonchemical and less toxic chemical control methods. Integrated pest management (IPM), specifically scouting, may be useful for LSPs to manage pests more sustainably and market new services, such as biological control releases. Little published literature details LSP scouting practices or consumer acceptance of scouting services. The goal of this study was to determine if IPM-aware consumers were more likely to purchase a scouting program offered by a LSP. A third-party panel service distributed an online survey across the United States. The final sample included 928 usable responses. Data were analyzed using a binary logistic regression model. Fifty-seven percent of respondents reported having some knowledge or that they were very knowledgeable of IPM. Increased consumer knowledge of IPM increased purchase likelihood. Respondents who self-reported “some knowledge” (5.6%) and “very knowledgeable” (8.6%) of IPM were more likely to buy scouting services. Respondents 65 years of age and older were 13.1% less likely to purchase a scouting service, regardless of IPM knowledge level. Consumers open to purchasing a scouting program, may also be more willing to allow a LSP to use a combination of chemical and nonchemical methods to manage pests. Further research is needed to determine consumer willingness to pay for scouting programs as well as non-chemical treatment options offered by LSP.

Native plants are becoming increasingly popular choices for low-input ornamental landscapes in residential and commercial applications. Many nurseries and landscape professionals are currently growing or offering at least some native plants in response to this increasing demand. However, supplies are still limited and there are specific best management practices associated with growing, marketing, and maintaining native plants that need further development. In response to this need from the green industry, replicable, applied programming focused on supporting growers who are currently producing or have an interest in producing native plants was developed. To first prioritize the needs of the industry, a state-wide native plant needs assessment survey was developed and disseminated to nursery and landscape professionals. The survey received 60 responses and indicated that native alternatives to invasive species, deer resistant native plants, and new cultivars of native plants were among the top priorities, in addition to IPM practices, stress tolerance, and propagation protocols. Based on this direction from stakeholders, extension programming was developed to meet these needs and support the green industry in their production and marketing of native plants. Educational programs focused on commercial native plant production and management were developed and delivered both in-person and virtually through webinars, while twilight meetings, including sessions at established native plant nurseries, facilitated grower-to-grower learning and interaction. Program evaluation surveys indicated strong metrics for knowledge gain, incorporating more native plants in their operations, reducing inputs, and achieving better pest control measures. Field trials comparing cultivars of deer-resistant native ornamental grasses offered growers and landscapers a chance to observe how these plants performed throughout three growing seasons, while offering a low-input alternative to non-native species in the landscape. Propagation trials were conducted to begin optimizing protocols for both vegetative cuttings and seed propagation of locally collected native ornamental plants, with success rates documented for each species using standard propagation protocols. A video was also created and shared with stakeholders showcasing a virtual tour of a commercial golf resort that has successfully incorporated native plants into their landscape, thus serving as an example for how to achieve an ornamental landscape aesthetic using native species. While native plant species may vary among ecoregions, this comprehensive approach is replicable and has been met with a high degree of satisfaction from commercial horticulture professionals.