ASHS 2025 Conference

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. Recent experiments have shown that SB grafted plant have higher plant vigour and bear fruits 7-10 days later than regulate plants leading to farmers losing early profitable watermelon market. Similarly, grafted watermelon nursery is 4-5 times more expensive than regular nursery which leads to reluctance among growers for adoption of this effective management strategy. To fill these gaps for informed adoption of SB grafted nursery, a field experiment was conducted at Blackville SC. The experiment comprised of three transplanting times (April 1, 10 and 20) and four transplant densities (1800 non-grafted, 1800, 1550 and 1300 grafted plants/acre) in a split plot design. The highest plant vigour rating was observed in SB grafted nursery at 1800, 1550 and 1300 plants/acre as compared to 1800 non-grafted plants/acre. April1 and April 10 recorded the highest fruit yield at first harvest as compared to April 20 transplanting. Similar fruit yield was observed for different transplanting times and density at second, third and fourth picks. Transplanting of SB grafted plants at 1300 plants/acre recorded the highest total fruit yield as compared 1800 and 1550 grafted and 1800 non-grafted plants/acre. Highest gross and net returns were observed in 1300 grafted plants/acre as compared to 1800, 1550 grafted and 1800 non-grafted plants/acre. The experiment will be repeated in 2025 to collect two years of data.

Evaluating Rootstock for Fresh Market Tomato Yield, Quality and Sustainability Tsedeniya Getahun, Harlene Hatterman-Valenti, Collin Auwarter Department of Plant Science, North Dakota State University Fresh market tomatoes are widely grown by specialty crop producers in North Dakota due to their profitability in the fresh market/local foods segment. However, with North Dakota's short growing season, growers often use high-tunnels for season extension to protect the crop from early and late frost events. Unfortunately, tomato plants often face numerous soil and disease challenges due to limited growing space in the high tunnel. Inadequate leaching of soluble salts in the soil and limited crop rotation contributes to salt and disease inoculum buildup in the soil that threatens the health of tomato plants and may cause serious losses in high tunnels. This two-year project with the first year completed in 2024, aims to evaluate the improvement of tomato production by grafting an heirloom, fresh market and paste tomato cultivar with excellent fruit quality characteristics onto rootstocks that are resistant to various abiotic/biotic stresses under high tunnel production. Tomato scion ‘Bigboy’, ‘Brandywine’ and ‘San Marzano’ (indeterminate), and ‘BHN 589’ (determinate) were grafted on to six rootstocks: ‘Arnold’ (generative), ‘DR0141TX’ (generative and vegetative), ‘Estamino’ (generative), ‘Fortimino’ (vegetative), ‘Maxifort’ (generative) and ‘Multifort’ (generative). Scion selection significantly influenced marketable yield, whereas rootstock had no significant impact. This effect was observed in ‘Big Boy’ but not in ‘San Marzano’ or ‘Brandywine’. ‘Big Boy’ grafted onto ‘Multifort’ or ‘Fortamino’ produced the highest marketable yield, followed by ‘Arnold’, Maxifort’, and ‘DR014TX’, with the lowest yield observed in non-grafted Big Boy’. ‘DR0141TX’ and ‘Multifort’ increased stem diameter and San Marzano tomatoes grafted onto Maxifort, Multifort, and Fortamino had the tallest plants. The trial will continue for another year to further evaluate the benefits of grafting for high tunnel tomato production in North Dakota.

The goal of the project is to understand the suitability of different scions when grafted onto commonly used watermelon rootstocks in California. This scion variety trial was conducted in 2024 within a commercial watermelon field near Stockton, California. Six different scions (Captivation, Fascination, Citation, Embasy, Melody, and Summer Breeze), categorized by horticultural characteristics such as maturity, fruit size, and color, were grafted onto three widely used watermelon rootstocks in California (Camelforce, Cobalt, and Carolina Strongback). The three rootstocks are grouped into interspecific hybrid squash (Cucurbita maxima x Cucurbita moschata) and Citron (Citrullus amarus). The field experiment was arranged as a randomized block design including eighteen treatments replicated three times. Each plot was 60 ft long and contained 10 triploids and 3 grafted pollenizers (Sentinel). The field was mechanically transplanted on May 14, 2024. In-season plot maintenance included vine separation multiple times to ease data collection and harvest. Canopy coverage was measured using a handheld crop sensor starting at 10 days after transplanting and thereafter at an approximate interval of two weeks for a total of eight measurements. With the help of farm crew, three harvests were conducted on August 5, 12, and 26. Total yields from each harvest and fruit quality taken from the first harvest were recorded and compared among the rootstock-scion combinations. For quality assessment, fruit length and width were measured by yardstick. Fruit flesh firmness was measured using a fruit penetrometer at the spots 1/3 and 2/3 distance from the blossom end after a melon was cut in half. Rind thickness at the blossom and stem ends were measured with a caliper. Sugar content (⁰Brix) was measured by scooping the center flesh of each half and reading the results through a portable reflectometer. Canopy coverage showed no significant differences among the treatments. For yield, four out of six scions (Fascination, Citation, Embasy, and Melody) produced the highest total yield (ton/acre and no/acre) when they were grafted onto Camelforce, while Captivation and Summer Breeze resulted in higher total yield when grafted with Carolina Strongback. A notable difference was observed in fruit quality for ⁰Brix and firmness that Carolina Strongback produced the lowest firmness and highest ⁰Brix when grafted with all six scions. These results provide a helpful advantage for growers in California who are considering grafting in their production. Continuous assessments will be conducted to further aid in the understanding of field performances from different rootstock-scion combinations.

New Mexico green chile is a labor-intensive crop, with harvesting posing increasing challenges due to labor shortages and rising costs. To meet growing consumer demand, farmers are transitioning to mechanical harvesting, traditionally reliant on direct seeding, which promotes strong taproots and minimizes uprooting. However, transplant seedling establishment, which allows multiple harvests, produces a root system less suitable for mechanical harvesting. This study evaluated transplant sowing methods to develop taproots compatible with efficient mechanical harvest. In 2024, ‘NuMex Odyssey’ was planted using three methods, direct seeding, ihort® Q plugs, and paperpots®, at the NMSU Agricultural Science Center in Los Lunas, NM. The study employed a randomized complete block design with five replications. Plant architecture, root, and yield data were collected. Preliminary findings show no statistical difference in marketable green fruit yield among the planting methods during mechanical harvest. However, taproot lengths of ihort Q plugs and direct-seeded plants were significantly longer than those of paper pot transplants. These results suggest that taproot length did not impact marketable green fruit yield during mechanical harvest. The findings indicate that ihort Q plugs and paper pot transplanting methods have potential for efficient mechanical harvesting of New Mexico green chile.

Bare-root transplants are the primary planting material used in strawberry production. They are grown in open-field conditions and dug up at maturity before shipment to fruit production sites. Delayed digging exposes transplants to different amounts of winter chilling (

Consumers seek locally grown tomatoes for their superior flavor, making them a valuable crop for local vegetable growers. Tomato production can be difficult with the temperature requirements for fruit set, development, and ripening. Optimum growing conditions are available for a short period in Oklahoma, causing a distinct decline in production during late July and August. A field experiment was designed to investigate the success of late planted, heat tolerant tomatoes in Oklahoma field conditions, as well as explore the relationship between physiological responses and season-long temperatures. The experiment utilized a split plot design with three transplanting dates as whole plot and five cultivars as subplot. ‘Red Snapper’ and ‘Laguna Red’ were selected as potential heat sensitive cultivars. ‘Bella Rosa’, ‘Volante’, and ‘Florida 91’ were selected as heat tolerant cultivars, based on previous trial information. Planting occurred on April 23, May 9, and May 23 to represent early, mid, and late plantings dates, respectively. Physiological measurements were collected every two weeks and included electrolyte leakage, net photosynthetic rate, stomatal conductance, leaf temperature, and chlorophyll fluorescence. Plants were harvested routinely from June to the end of August. Cultivars were not found to be significantly different in the trial for yield or physiological responses. The early planting date was the most productive, compared to mid and late. Yield dropped dramatically for all planting dates in August. There was a strong positive correlation between electrolyte leakage and temperature and a moderate negative correlation between photosynthetic rate and average daily temperature. These correlations indicate that physiological parameters may be able to provide insight into late season thermotolerance. Future research will involve cultivar screenings in controlled environments to promote a wider range of responses to temperature.

Many direct-market farmers in western Washington are interested in sweetpotatoes (Ipomoea batatas) for crop rotations, to increase farm sales, offer a culturally relevant crop to consumers, and adapt to climate change. We conducted research station and on-farm trials in 2023, 2024, and 2025 with the goal of testing cultivars, developing production guidelines, and introducing sweetpotato as a new crop for the region. The trials were a partnership between WSU researchers, who led the research station trials, and WSU Extension, who led the on-farm trials. Research station trials provided yield and wireworm resistance data for nine cultivars and breeding lines, and on-farm trials introduced sweetpotato to farmers in the region. On-farm trial participants were provided with slips or roots of three sweetpotato cultivars and a production guide. In 2023, 20 farmers across three counties signed up to participate, 15 farmers planted trials (75% of signups), 11 farmers returned surveys with some data (73% of planted trials), and 5 farmers provided complete data (33% of planted trials). Due to varying management practices and incomplete responses, 2023 on-farm trial data were largely unusable for evaluating yield or wireworm resistance. In 2024, 33 farmers across nine counties signed up to participate, 29 farmers planted trials (88% of signups), 25 farmers returned surveys and/or had data collected by a WSU Extension Field Assistant (89% of planted trials), and 20 farmers provided complete data (71% of planted trials). Hiring a part-time field assistant in 2024 who visited farms and collected data increased farmer response rate and data completeness. Yet, on-farm trial yield and wireworm resistance data still were not fully usable due to inconsistencies in how data were collected, and lack of adherence to production guidelines. In 2025, we redesigned on-farm trial data surveys to focus on farmers’ perceptions regarding suitability of sweetpotato production and marketability for their farm. Participating farmers are uniquely well-suited to answer these qualitative questions, which will assess if sweetpotato has been successfully introduced in the region. In all years of the project, online growing classes, in-person field days, and farm walks proved useful for introducing sweetpotato to new farmers in the region. Visits to on-farm trial locations proved an important avenue of offering support to farmers experimenting with sweetpotato. Completed surveys and conversations with on-farm trial participants provided valuable feedback that was incorporated into our sweetpotato production guide, and expanded and improved our on-line resources including several short production videos.

Urban areas are expanding throughout the world, increasing infrastructure and impermeable surfaces and concurrently decreasing quantity and quality of natural landscapes. With a decrease in green spaces, human communities experience an increase in food scarcity. Ecological communities experience a decrease in biodiversity and suitable habitat. Here, we aim to utilize native wildflowers, vegetable crops and urban infrastructure to provide healthy food as well as biodiversity options to urban areas. In this study we examine (a) how the presence of native perennial Colorado wildflowers may influence the yield of crop plants, specifically the three sister’s guild of maize, beans and squash, plus sunchokes and sunflowers and (b) to evaluate how the crop yields may differ between sites in full sun and partial shade landscapes. To do so, we utilize green roofs and ground plots at Colorado State University in Fort Collins, Colorado to evaluate the yield differences. We hypothesize that the crops with wildflowers nearby will produce a higher crop yield than the crops grown without wildflowers. Additionally, we expect that shade treatments will reduce yield compared to the full sun treatments. Thus far with preliminary data analysis, we find crops grown on the green roof with native wildflowers nearby had a higher average leaf number (as a proxy for the size of the plant). The yield of the squash crop was the highest on the green roof with the native wildflowers while the yield of the pole bean crop was highest at grade with native wildflowers nearby. This shows the proximity to wildflowers may have a significant effect and there may be an effect of shade for the yield of pole beans. With this research, we hope to provide notable insight to continue working towards the most efficient crop growth on green roofs in urban environments.

Climate change progression has created many challenges for our current agriculture system such as the degradation of arable land and more intense weather patterns. Rates of food insecurity and population growth are simultaneously increasing in urban areas, so reimagining food production and land management is vital for the future of agriculture. Rooftop agrivoltaics (RAV), growing crops under solar panels on a green roof, may be an effective way to produce clean energy and high yields of specialty crops in underutilized spaces. Chile peppers hold economic and cultural significance to the southwest region of the US. Previous studies show chile peppers perform better under 35% shade than in full sun due to heat stress reduction. This study focused on three cultivars of chile peppers: ‘Hatch’, ‘Mosco’, and an unnamed CSU experimental. Individuals of each cultivar were planted in four on the green roof (under opaque photovoltaics (PV), under bifacial PV, under 40% shade cloth, and full sun) and in one at-grade plot. The 40% shade cloth was used to simulate semi-transparent solar panels. Plants were evaluated by yield (fruit production), water efficiency (stomatal conductance), and plant growth index (average of two widths and height). Analysis shows yield was significantly higher in the full sun and shade cloth plots than all other plots, possibly due to the bifacial and opaque plots providing too much shade for optimized fruit production. Stomatal conductance was reduced in the shade cloth, bifacial, and opaque plots in the first part of the growing season and varied by cultivar and treatment at other times. Plant growth index was highest for plants grown in the shade cloth plot at most time points, but significance varied by cultivar across treatments. Growing chile peppers in RAV systems utilizing semi-transparent solar panels can reduce plant water use while producing more fruit than traditional at-grade growing. Sensory evaluation using a just-about-right (JAR) test and was conducted to assess consumer acceptance of sensory attributes of roasted ‘Hatch’ and ‘Mosco’ chile peppers grown in full sun on a green roof and at grade. A standard 9-point hedonic scale was used to assess overall liking. There was no significant difference in JAR ratings for each of the 7 attributes assessed and no significant difference in overall liking. Growing ‘Hatch’ and ‘Mosco’ chile peppers on green roofs does not significantly impact consumer acceptance. This provides urban farmers with more confidence to grow chile peppers on green roofs.

Intercropping mushrooms with field-grown vegetables may provide farmers additional revenue without sacrificing bed space or investing in indoor production facilities. The King Stropharia mushroom (Stropharia rugosoannulata), also called wine cap, can colonize organic material, like woodchips or straw mulch, making it a good candidate for intercropping with vegetables that can be grown on organic mulches. However, no research has evaluated the impact of this strategy on the vegetable yield. This project seeks to evaluate the compatibility of intercropping wine-cap mushrooms with asparagus in woodchip mulch. A randomized complete block experimental design (RCBD) experiment was initiated in 2021, and data was collected during the 2022 and 2023 growing seasons. The trial evaluated two factors: intercropping – inoculated vs. non-inoculated and mulch depth – 0 in (control), 4 in, 8 in, and 12 in. Wine-cap mushrooms were successfully established in the inoculated plots. The woodchip mulch depth had no effect on the timing or overall yield and marketability of the mushrooms, although 4 in mulch produced a smaller proportion of small-medium, Grade 1 mushrooms resulting in higher average weight fruiting bodies compared to deeper mulch treatments. During the first spring harvest, wine-cap mushrooms were also observed on the edges of non-inoculated plots; therefore, we were unable to evaluate the effects of mushroom on asparagus growth. Woodchip mulch did not affect the date of first harvest or harvest duration in either year, except at 12 in depth, which delayed harvest and shortened the production season. Relative to bare ground, woodchip mulch only affected asparagus yield (by number or weight) at 12 in depth, which decreased the number and weight of harvested asparagus. In 2023, asparagus spears grown with 8 in non-inoculated woodchips weighed 80 % more, on average, than spears grown in 4 in and 12 in inoculated plots. While the experiment provides a proof of concept for intercropping wine-cap mushrooms with asparagus, further research is needed to determine whether intercropped mushrooms directly impact asparagus production.

Small-scale growers face challenges in optimizing the quantity and quality of new broccoli cultivars due to shifting weather patterns and the prevalence of heat-sensitive cultivars. This study aims to identify high-performing cultivars and optimal planting dates for late spring to enhance the competitiveness of cool-season specialty crop growers in North Dakota. The research took place at the NDSU Horticulture Research Farm, near Absaraka, ND, to examine how planting time impacts cultivar performance through field experiments on four planting dates: May 1st, May 15th, June 1st, and June 15th. Early planting of broccoli, particularly in May, resulted in higher yields and better quality across all cultivars. Some cultivars outperformed others. 'Jacaranda' yielded significantly more than any other cultivar, which is a noteworthy. Conversely, 'Gypsy' and 'Monty' had yields similar to the standard cultivar 'Green Magic', while 'Purple Peacock' yielded less across all planting dates, indicating poor adaptation. Early planting benefited all broccoli cultivars, with later dates bringing higher temperatures that negatively impacted head formation and curd size across all cultivars. These elevated temperatures alter key physiological parameters, such as increased transpiration and vapor pressure deficit, while potentially reducing photosynthetic efficiency and stomatal conductance. The physiological changes induced by higher temperatures ultimately lead to accelerated maturation, smaller heads, and reduced overall yields. Notably, early planted broccoli potentially achieved up to 35% higher yields than late-planted crops. The findings provide valuable insights into the relationships between planting dates, temperature effects, and cultivar-specific responses, emphasizing the importance of these factors in maximizing yield and quality for cool-season specialty crop growers in the region.

As a tropical crop, ginger (Zingiber officinale) rhizomes will not fully mature inside high tunnels in Virginia. The objective of this study was to monitor the growth and development of ginger rhizomes throughout the season, as reflected in the fresh and dry weights. The ultimate goal was to determine the harvest time of rhizomes for profitable fresh and dry ginger. Ginger cultivars Bird, Blue Ring, Buffalo Gung, Chinese, Indian, Peruvian Yellow, Red, and Yellow were pre-sprouted in a greenhouse in mid-March of 2024. Sprouted ginger rhizomes were transplanted into raised beds in a 26’ x 150’ high tunnel on May 16, 2024, on Randolph Farm of Virginia State University. The in-row spacing was 1 ft. Monthly destructive samples of 3 plants/cultivar (one in each of the 3 replications) were conducted for fresh and dry weights. Cultivars differed in the rhizome fresh and dry weight over time. Fresh rhizome weight of cultivar Bird, Chinese, Indian, Peruvian Yellow and Yellow reached 0.5 lb/plant 3 months after transplanting (MAT). “Red” had significantly higher percentages of dry weight (> 8%) than other cultivars (< 6%) until 5 MAT, when other cultivars began to catch up. Pooling data from all cultivars, we found that ginger rhizomes will reach 0.5 lb/plant, which is a profitable yield, around 3 MAT. The percentage of dry weight remained low (5.3-5.7%) until 4 MAT, but the number spiked quickly to 8.3 % at 5 MAT and 13.4 at 6 MAT. Our results suggest that young ginger harvest can happen as early as 3 MAT. However, to harvest rhizome for dry ginger, 5 MATs are needed and harvest should occur at the end of season for maximal yield. “Red” is a unique cultivar. It has the lowest yield (1.3 lb/plant), but its percentage of dry weight remained high (8.2-8.8%) for 5 months, compared to all other cultivars (4.4-6.4%).

Sweet corn is one of the important high-value crops in the Columbia Basin, and it requires a significant amount of nitrogen (N) input to achieve the optimal yield target. However, with many varieties planted, the N requirements should be evaluated to ensure the economic and environmental sustainability. In a field trial conducted from May to August in Hermiston, OR, six sweet corn varieties were tested under six nitrogen application rates (ranging from 0 to 308 kg N/ha). The results showed that the optimal N rate for maximizing corn yield and marketable ear number was approximately 247 kg/ha across all tested varieties. Among the varieties, Driver R and Sorel produced the highest yields, the most marketable ears, and relatively longer ear lengths, while Turbine had the lowest yield. Megaton had the highest proportion of non-marketable yield, which may reduce its marketable value, although it produced the longest cobs. Multiple-year evaluation is needed to develop a conclusive recommendation for nitrogen fertilization of sweet corn in the region.