ASHS 2025 Conference

This workshop will focus on the educational (University) and Technical Programs geared towards Organic Horticulture. Universities vary greatly in their organic programs, student interest in organic programs, and facilities. Similarly, the technical assistance provided from growers varies from state to state. Recent Transition to Organic Partnership Program (TOPP) programming, has created more interest in providing this assistance. This workshop will focus on discussing the challenges to organic education both at the undergraduate and farmer level.

Speakers:

• Kate Cassity-Duffey, University of Georgia
• Mary Rogers, University of Georgia
• Christian Stephenson University of Nebraska-Lincoln
• Christine Coker University of Mississippi

A forum for discussion of potential collaborations with regards to fruit, vegetable, and edible crops – i.e. citrus, breeding, production systems, postharvest, pomology, crop management, viticulture, etc.

Sweet Corn (Zea mays) is a popular warm season specialty crop grown in the United States and around the world. Sweet corn production can encounter obstacles including weed competition and nutrient losses, particularly nitrate leaching. This study explored the influence of third-year clover living mulch systems on organic sweet corn production, and the impact of historic in-row soil management practices on sweet corn growth and yield. Conducted in 2024 at the SDSU Southeast Research Farm, Beresford, SD, USA, this research investigated the impact of established clover living mulch on ‘Who Gets Kissed©’ sweet corn (High Mowing Seeds). Two years prior to sweet corn planting, three clover cultivars were established: ‘Domino’ white clover (Trifolium repens), ‘Aberlasting’ white x kura clover (T. repens x ambiguum), and ‘Dynamite’ red clover (Trifolium pratense), which were compared with a bare-ground control. During the past two seasons, within each clover whole plot, four in-row soil management subplots (till, till landscape fabric, no-till, no-till landscape fabric) were established. The established plots were planted with acorn squash (cucurbita pepo) in the first year, followed by fall cabbage (Brassica oleraceae var. capitata) in the second. Prior to sweet corn production, all treatments were strip-tilled to temporarily delay clover and prepare a planting bed for direct seeding of sweet corn with a single row planter. No landscape fabric was used in-row to align with medium to large scale production practices. Till treatments were weeded with a stirrup hoe and represented tilled cultivation. No-till treatments were hand weeded with the proper hand tool to minimize soil disturbance. Sweet corn data was collected to understand the impact of clover variety and soil management practices on crop health, weed suppression, and yield. Yield was graded in accordance with the USDA Marketable Standard for sweet corn cash crop production. Weed biomass decreased as the season progressed and sweet corn canopy closed; however mid-season drought conditions decreased clover growth. Prior years of soil management did not affect yield and production (p ≤ 0.8), but clover living mulch systems did (p ≤ 0.04). Over 50% of the graded sweet corn was in the US No1 and US No 2 categories. Bare ground treatment plots were first to reach maturity and produced the highest percentage of marketable ears. Farmers who are interested in growing sweet corn could utilize living mulch systems after key considerations such as water availability, early season maintenance, and scale of production.

Grafting and microbial inoculation are promising strategies for enhancing organic pepper production, mainly to manage soil-borne diseases and optimize nutrient utilization. This study conducted in a high tunnel environment evaluated the performance of two Phytophthora-resistant rootstocks, CM-334 and YC-207, grafted with a common scion (Mama Mia Giallo), and the application of a mycorrhizal and bacterial mix consortium under two organic fertilization rates (100:40:60 kg NPK ha-1 as optimal rate and reduced to half as low rate). Our hypothesis explored whether the synergy of microbial inoculation and grafting could compensate for the reduced growth of the low rate by improving nutrient use efficiency. Chlorophyll content was higher (~10 %) in inoculated plants compared to non-inoculated plants under low fertilization. At the peak bloom stage, leaf net photosynthesis was similar at both fertilization rates, while inoculated plants had an increase in plant water use efficiency (~12 %). Microbial inoculation and low fertilization induced early flowering compared to non-inoculated plants grown at optimal fertilization rate. Under low fertilization, inoculated YC-grafted plants exhibited higher electron transport rate, stomatal conductance, and transpiration rate than other inoculated plants. CM-grafted plants responded negatively to inoculation at optimal fertilization, as shown by the lower net photosynthesis (~16 %) and stomatal conductance (~44 %) compared to non-inoculated plants. The correlation of these physiological traits with fruit yield, quality, and soil health will provide further understanding applicable to rootstock selection and microbial inoculation to optimize pepper production, particularly in resource-limited conditions.

Modern agricultural production systems have become highly specialized and input-intensive models that boost food production and lower production costs. While this has allowed us to meet our rising food demand, it has led to environmental degradation. Moreover, these systems lack resilience and sustainability against higher supply costs and shifting environmental conditions. Integrated Crop Livestock Systems (ICLS) at the field level are an alternative that balances productivity with environmental responsibility by combining crop and animal rotations. Often incorporating practices such as cover crops, reduced or no-tillage and minimal external inputs. ICLS can improve soil health, enhance nutrient cycling, and improve resilience through diversification. Livestock is central to ICLS and can be adapted to farm specific needs. For small organic farmers, poultry is an attractive option due to its easy handling and regular production of meat or eggs. However, chickens can carry pathogens such as Salmonella.spp and Listeria monocytogenes, raising food safety concerns. With no specific guidelines for ICLS implementation, organic farmers are encouraged to follow the 90 -120 USDA National Organic Program (NOP) rule for application of raw manure. This research aims to clarify food safety implications when integrating poultry into specialty crops systems The study followed organic practices on organic land. Designed as a Randomized Complete Block Design (RCBD) with split plots with poultry foraging on high or low cover crop residue, or no grazing as the main plot with tillage or no-tillage as the split plot factor. Chickens foraged for 5 weeks before processing for-carcass weight, meat yield and Salmonella.spp cecal prevalence. After chickens were removed from the cover crop, organic tomato (Solanum lycopersicum ‘Granadero’) seedlings were planted. We measured tomato yield per plant. Prevalence of Salmonella Spp. was determined from cecal and soil and tomato surface samples at two-time points; directly after chicken removal at harvest (n= 348 environmental samples). Neither foraging nor tillage type had a significant effect on tomato yield, suggesting that animal integration is a viable option for cover crop management and farm diversification. After the chicken removal all environmental samples tested negative for Salmonella spp. At harvest, Salmonella appeared in 17 of 348 samples (4.88%), suggesting that integrating chickens does not necessarily elevate the risk of produce contamination and that other environmental factors affecting Salmonella prevalence should be further studied.

Anaerobic soil disinfestation (ASD) is a potential biological alternative to chemical fumigation for managing soilborne pathogens and enhancing soil health in strawberry production. The effectiveness of ASD for improving organic strawberry systems deserves more in-depth research. Building upon an ASD input rate study, this on-station experiment, conducted at Citra and Balm in Florida, assessed the impacts of two ASD treatments, including molasses (13.9 m³/ha) combined with either 9.5 (ASD1) or 14.25 Mg/ha (ASD2) of Everlizer, a heat-processed poultry manure product on strawberry yield performance. Using a split-plot design with four replications, the three-week ASD treatments and no ASD control were included in the whole plots and six strawberry cultivars (i.e., ‘Florida127’, ‘Florida Brilliance’, ‘Florida Medallion’, ‘Florida Pearl’, ‘Ember’, and ‘Encore’) were included in the subplots. A sunn hemp summer cover crop was grown, and the soil was incorporated before ASD establishment and Fall strawberry planting. At Citra, ASD1 and ASD2 significantly increased marketable fruit yield compared to the no ASD control by about 25% and 21%, respectively. However, this increase was accompanied by a modest increase in unmarketable yield, particularly under ASD1. The cultivar effect was also significant (p < 0.001), with ‘Encore’ and ‘Ember’ exhibiting the highest marketable fruit yield, while ‘Florida Brilliance’ had the highest unmarketable fruit yield. A similar trend was observed at Balm, where ‘Encore’ was the cultivar with the highest marketable yield. In addition, marketable fruit yield was increased by 7% under ASD1 and 36% under ASD2 relative to the control. On the other hand, ASD1 and ASD2 also led to higher unmarketable fruit yields by 13% and 35%, respectively, relative to the control. While the main effects of ASD treatment and strawberry cultivar were significant at both locations, no ASD by cultivar interaction was observed, indicating that cultivar performance trends were relatively stable across ASD treatments. Across locations, ASD significantly improved total fruit yield, with ASD1 promoting a higher level of marketability by lowering the amount of unmarketable fruit. These results demonstrate the application of ASD for enhancing strawberry yield in sandy soils and subtropical environments and highlight the importance of cultivar selection for optimizing organic strawberry production systems and assisting with organic transition. Further assessments of ASD inputs and implementation, fruit compositional quality, plant nutrient uptake, and soil microbial activity are expected to provide more insights into developing ASD practices for advancing sustainable strawberry production in Florida and the Southeastern region.

Aminoethoxyvinylglycine (AVG) is a plant growth regulator widely used in apple production to delay ethylene-mediated ripening and improve fruit quality. This has become a key tool for delaying ripening, optimizing harvest time, and reducing preharvest drop. The development of an organic AVG is key for organic apple production, where growers currently lack effective tools to delay ripening and manage fruit quality, both at harvest and postharvest. A new organic-compliant formulation, Retain® OL, was developed to meet the needs of the organic industry. To assess the potential of organic AVG, field trials were conducted over three seasons in commercial Gala and Honeycrisp orchards. Different application rates were tested, and fruit samples were collected at preharvest, harvest, and postharvest intervals. Fruit maturity and quality attributes including flesh firmness, skin color, Index of Absorbance Difference (IAD), starch index, total soluble solids (TSS), among others were measured. Postharvest evaluations continued for up to nine months in controlled atmosphere (CA) storage. Retain® OL application effectively delayed fruit maturity in both Gala and Honeycrisp apples in a dose- and timing-dependent manner. Treated fruit exhibited higher firmness at harvest and after extended storage. IAD values were consistently improved, indicating a slower ripening process and delayed loss of chlorophyll. In Gala, red skin color development was maintained or enhanced, whereas Honeycrisp showed a slight reduction in coloration. The starch index was higher in the untreated control at both preharvest and harvest stages, indicating more advanced ripening. Total soluble solids (TSS) showed variable responses across seasons, influenced by treatment rate, timing, and cultivar. Depending on these factors, TSS levels were maintained, improved, or slightly reduced compared to the control. This study provides new insights into the pre- and postharvest effects of Retain® OL. Overall, organic AVG demonstrated benefits comparable to the conventional formulation, offering a valuable tool for harvest management in organic apple production. These findings support the integration of organic AVG into organic systems to enhance harvest flexibility, improve storability, and increase overall fruit marketability.