High Tunnel Production Research Articles

Evaluation of Selected Biological and Chemical Treatments against Soil-Borne Diseases of Ginger in High Tunnel Production

With its multifaceted health benefits, ginger is one of the commonly consumed dietary condiments with continued demand worldwide leading to more importation into countries such as the U.S. The rhizome of ginger, the seed-piece but also the edible portion, is highly vulnerable to pathogen infections causing seed-piece and soil-borne diseases (SSDs). Laboratory and high tunnel (HT) studies were conducted between 2018 and 2020 to evaluate the effect of soil and transplant drenches of selected biocontrol agents (BCAs) and chemicals. In vitro dual-culture tests revealed that the Trichoderma harzianum strain T-22 (Th-22) grew significantly faster than Fusarium oxysporum f.sp. zingiberi (Foz), the fungus causing yellows and rhizome rot in ginger. Th-22 grew more than three times faster than Foz within 3 days and engulfed the pathogen within 7 days when incubated at 30 °C. The bioproducts (RootShield® Plus, LifeGard®), an insecticide/nematicide (Vydate®) and disinfectant (10% Clorox) tested against Foz and any pre-existing pathogens in a HT significantly reduced severity of yellowing and rhizome rot when compared with the non-treated control. Yield was significantly higher for RootShield® Plus compared to the control in one of the trials. Spatially, declining ginger growth but an increased incidence of SSDs were observed as one walked from the door towards the back of the HT. Phospho-lipid fatty acid analysis showed better microbial activity on soils that received drenches of BCAs than on soils sampled pre-treatment.

Instrumental and sensory analyses of fruit quality attributes of grafted grape tomatoes in high tunnel organic production systems.

'Vegetative' and 'generative' tomato rootstock types have been proposed based on their different effects on tomato scion growth performance; however, their impacts on fruit quality have not been characterized. No study has been conducted in which the effects of rootstock on grape tomato quality attributes were assessed using sensory and instrumental methods of evaluation. Here, we conducted two experiments to examine the influence of 'DR0141TX', 'Estamino', and 'Multifort' rootstocks (vegetative, generative, and uncharacterized, respectively) on fruit quality properties of determinate and indeterminate grape tomato scions under organic production in high tunnels, including color, size, firmness, dry matter content, soluble solids content (SSC), titratable acidity (TA), pH, and consumer sensory attributes. In both experiments, grafting 'Sweet Hearts' indeterminate grape tomato onto 'DR0141TX', 'Estamino', or 'Multifort' increased fruit size and led to negligible effects on sensory attributes and instrumental measurements of fruit quality attributes. For 'BHN 1022' determinate grape tomato, rootstocks did not exhibit any major impact on fruit quality attributes in Experiment 1. However, fruit quality was compromised by grafting per se and rootstocks, especially 'Multifort', in Experiment 2, as reflected by reduced SSC, TA, and SSC/TA and lower scores for overall appearance, overall acceptability, tomato flavor, overall texture, and sweetness. In general, 'vegetative' and 'generative' rootstocks showed comparable effects on sensory evaluations and instrumental measurements of grape tomato quality attributes for both indeterminate and determinate scions. More research is needed to better characterize rootstock effects on fruit quality, including the flavor-related compounds under different growing conditions. © 2022 Society of Chemical Industry.

Cladosporium Leaf Spot Caused by Cladosporium variabile in Winter High Tunnel Production of Spinach (Spinacia oleracea) in Maine, United States.

In January 2021, leaf spots were observed on 1 of 22 proprietary spinach cultivars in a trial under high tunnels in Albion, ME. Approximately 1% of plants were symptomatic with <30% leaf area affected. Some spinach growers reported ≤100% incidence in high tunnels in the northeastern USA. Leaf spots on the cultivar in Albion were <5 mm in diameter and tan-colored with dematiaceous spores in short chains on long conidiophores at the center of older lesions. Lesions were surface-sterilized in 0.6% NaOCl for 90 s, rinsed in sterile water, dried, and placed on clarified V8 agar medium amended with chloramphenicol (100 µg/ml). Three Cladosporium isolates (Cds053, Cds055, and Cds057) produced olive-green colonies with dematiaceous conidia, 0- to 2-septate, catenulate, and 8.0-28.0 µm (16.6 ± 0.6 µm, mean ± standard error) x 4.0-12.0 µm (8.3 ± 0.2 µm) (n = 50/isolate). The partial internal transcribed spacer (ITS) region of rDNA, translation elongation factor 1-α gene (tef1-α), and actin gene (act) were amplified and sequenced with primer sets UNUP18S42/UNLO28S576B (Bakkeren et al. 2000), EF1-728F/EF1-986R (Carbone and Kohn 1999), and ACT-512F/ACT-783R (Carbone and Kohn 1999), respectively. The sequence of each locus was identical among the isolates. The tef1-α (GenBank Accession No. MZ905363) and act (MZ905362) sequences were identical to accessions of tef1-α (EF679480.1) and act (EF679556.1) of C. variabile (Cooke) G. A. de Vries, whereas the ITS rDNA sequence (MZ893461) was identical to that of many Cladosporium spp., including C. variabile. Each isolate was inoculated onto four replicate 42-day-old plants of each of the spinach cultivars Viroflay and Mandolin. The plants were enclosed in plastic bags for 24 h, atomized with a spore suspension (106 conidia/ml) prepared from potato dextrose agar colonies of each isolate, and returned to the bags for 24 h. Four plants of each cultivar were atomized with deionized water as a control treatment. Plants were arranged in a randomized complete block design. By 5 days, tan spots had developed on Cladosporium-treated plants of each cultivar. By 14 days, Mandolin had developed more severe lesions (20.0 ± 2.8%, mean ± standard error of leaf area with symptoms) than Viroflay (5.4 ± 0.4%). No control plants treated with water developed lesions. After 15 days, a leaf from a plant of each treatment was incubated in a moist chamber at 20˚C with a natural diurnal light cycle. Sporulation was observed at the center of lesions from Cladosporium-inoculated plants <24 h after incubation, and Cladosporium was re-isolated. The act locus amplified and sequenced from the re-isolates, as described above, had an identical sequence to that of the original isolates, fulfilling Koch's postulates. Empirically, Cladosporium leaf spot has established in winter high tunnel production of spinach in the northeastern USA (R. Katz, personal observation). To our knowledge, this is the first official documentation of the disease in Maine. The disease is favored by cool, humid conditions (Inglis et al. 1997). Management strategies under these conditions in Maine and greater New England include foliar applications of effective fungicides (du Toit et al. 2004), selection of partially resistant cultivars, cultural practices to reduce relative humidity and durations of leaf wetness, and planting pathogen-free or treated seed (du Toit and Hernandez-Perez 2005; Hernandez-Perez and du Toit 2006).

The Diversity of Passalora fulva Isolates Collected from Tomato Plants in U.S. High Tunnels.

High tunnels extend the growing season of high value crops, including tomatoes, but the environmental conditions within high tunnels favor the spread of the tomato leaf mold pathogen, Passalora fulva (syn. Cladosporium fulvum). Tomato leaf mold results in defoliation, and if severe, losses in yield. Despite substantial research, little is known regarding the genetic structure and diversity of populations of P. fulva associated with high tunnel tomato production in the United States. From 2016 to 2019, a total of 50 P. fulva isolates were collected from tomato leaf samples in high tunnels in the Northeast and Minnesota. Other Cladosporium species were also isolated from the leaf surfaces. Koch's postulates were conducted to confirm that P. fulva was the cause of the disease symptoms observed. Race determination experiments revealed that the isolates belonged to either race 0 (six isolates) or race 2 (44 isolates). Polymorphisms were identified within four previously characterized effector genes: Avr2, Avr4, Avr4e, and Avr9. The largest number of polymorphisms were observed for Avr2. Both mating type genes, MAT1-1-1 and MAT1-2-1, were present in the isolate collection. For further insights into the pathogen diversity, the 50 isolates were genotyped at 7,514 single-nucleotide polymorphism loci using genotyping-by-sequencing. Differentiation by region but not by year was observed. Within the collection of 50 isolates, there were 18 distinct genotypes. Information regarding P. fulva population diversity will enable better management recommendations for growers, as high tunnel production of tomatoes expands.

Effect of container size, substrate composition, and genotype on growth and fruit quality of young southern highbush blueberry in a container-based intensive production system

Southern highbush blueberry (SHB) production is continuing to expand worldwide. Innovative horticulture practices including container-based cultivation, evergreen management, high-density planting, and high-tunnel production have been explored to maximize the productivity and profitability of SHB production. However, there is a lack of information on the feasibility of integration of all these practices to establish an intensive production system in Florida. We aimed to test and optimize this intensive system by evaluating container size, substrate composition, and genotype. Two container sizes (50.5 L and 40.4 L), five different combinations of pine bark, coco coir, and perlite, and five SHB genotypes were tested in this study. Plant vegetative growth, yield, and berry quality were measured for two years. There were no impacts of substrate composition and container size on vegetative or reproductive growth during the two-year production period studied. Plant height and canopy width varied among genotypes due to their canopy architecture. Yields of each genotype ranged from 1.0 kg/bush to 2.5 kg/bush in the first year and ranged from 0.4 kg/bush to 2.1 kg/bush in the second year. Significant differences in the performance of five genotypes tested in this study indicated that is necessary to breed cultivars specifically for this intensive system.

Greenhouse and High Tunnel Production of Specialty Cut Flowers

The objective of this study was to determine best production practices for five different specialty cut flower species at an altitude of 7200 ft. Region-specific information about cut flower production is important because of unique environmental conditions. We grew five specialty cut flower species in two different growing environments: a greenhouse and a high tunnel. Flowers were grown year-round in the greenhouse and during late spring through fall in the high tunnels. We also used pinching as another production method for the potential increase in branching. The goals were to test the effects of species, growing environment, and pinching on the days from sowing to harvest, stem length, number of stems cut per plant, and marketable yield. Experiments were conducted at the University of Wyoming Laramie Research and Extension Center in Laramie, WY, to assess the potential for producing specialty cut flowers for local consumption. The species used in this study included ‘Princess Golden’ pot marigold (Calendula officinalis), ‘Lucinda Mix’ stock (Matthiola incana), ‘Double Mix’ strawflower (Helichrysum bracteatum), ‘Dara’ ornamental carrot (Daucus carota), and ‘Celway Mix’ cockscomb (Celosia argentea). Results showed significant species × environment and season interactions, indicating the importance of species and production practice selections. We successfully sold the cut flowers to the university student farm for community-supported agriculture shares and farm market sales, as well as to a local florist for use in floral arrangements. This study concluded that careful species selection for season and growing environment is essential for the successful integration of these niche cut flowers into current or future greenhouse and high-tunnel production in Wyoming.

Flowering Time and Productivity of Interspecific Grafts Between Pepper Species in Contrasting High Tunnel-sheltered and Open-field Production Environments in Costa Rica

The production of sweet peppers (Capsicum annuum) is often constrained in tropical environments by susceptibility to persistent soil-borne diseases, including bacterial wilt (Ralstonia solanacearum). However, the production of sweet peppers in high tunnels using sterile soilless media irrigated with nutrient solution offers the potential to reduce the incidence of bacterial wilt. An additional strategy for disease management is the use of sweet pepper scions grafted onto rootstocks that are resistant to soil-borne pathogens. Two sweet pepper cultivars grown extensively in the tropics, Nathalie and 4212, were used as scions and grafted onto the habanero pepper cultivar Habanero TEC (Capsicum chinense) and the aji pepper cultivar Baccatum TEC (Capsicum baccatum). Two cultivars related to the two rootstocks were prescreened for susceptibility to two virulent strains of bacterial wilt. Graft combinations were grown in two environments, a high tunnel with automatic nutrient solution irrigation of containers filled with sterile coconut fiber and an open field with known high levels of bacterial wilt inoculum. Self-grafted and nongrafted plants of scions were included as checks. The disease susceptibility screening showed that the area under the disease progress curve was consistently low for ‘Habanero TEC’ and ‘Baccatum TEC’ when inoculated with two virulent strains of bacterial wilt, suggesting that habanero pepper cultivars and, to a lesser degree, aji pepper cultivars may be useful as rootstocks in soils with bacterial wilt inoculum. Significant increases in yield, fruit number, and reduced time to flowering were observed in the high tunnel compared with the open-field environment. Individual fruit weight was reduced in the high tunnel compared with the field. Yield, fruit number, fruit weight, and time to flowering were consistent between scions regardless of rootstock. No differences were observed for yield, fruit number, fruit weight, or time to flowering of self-grafted and nongrafted scion checks. In the high tunnel, yield was higher in scions grafted onto ‘Habanero TEC’ compared with self-grafted and nongrafted checks. In the open field, yield and fruit number were highest on scions grafted onto ‘Habanero TEC’. Regardless of graft treatment, high-tunnel production in tropical environments can result in significant increases in yield and fruit number compared with open-field production. No advantage of grafted plants was observed in the high-tunnel production environment. In contrast, in the open-field environment, grafting sweet pepper scions onto pungent habanero rootstocks resulted in a significant increase in yield, fruit number, and fruit size compared with self-grafted and nongrafted checks. The increase was likely attributable to the resistance of habanero pepper cultivars to soil-borne diseases, including bacterial wilt.

Winter Production of Asian Leafy Greens in High Tunnels Using Biodegradable Mulches

Use of season extension tools such as high tunnels and diverse vegetable crops have been crucial in improving competitiveness of vegetable growers in Mississippi who operate on small- to medium-sized farms. Chinese cabbage, also known as pak choy or bok choy, has become increasingly popular due to numerous cultivar choices, fast maturity, high productivity, tolerance for frost, and its potential use for winter production in high tunnels in a subtropical climate. Five Chinese cabbage cultivars including ‘Asian Delight’, ‘Black Summer’, ‘Red Pac’, ‘Rosie’, and ‘Tokyo Bekana’ were evaluated for plant growth, yield, and mineral nutrient concentrations when grown with three types of biodegradable plastic mulches (BDMs) and one polyethylene (PE, or plastic) mulch in a high tunnel in two experiments from 30 October 2019 to 18 March 2020. The five tested cultivars varied in plant height, widths, leaf SPAD, fresh and dry plant weights, marketable yield, and macro- and micro-nutrient concentrations. ‘Tokyo Bekana’ produced the highest marketable yield and fresh and dry plant weights in both experiments. The three BDMs resulted in similar marketable yield and mineral nutrients in tested cultivars and similar temperatures of leaf, mulch, and substrate compared to the PE mulch. The high tunnel provides a viable way for the winter production of selected Chinese cabbage cultivars in a subtropical climate with possible different yields between production cycles due to varying microenvironment in those months.

Effect of Light Characteristics on the Sensory Properties of Red Lettuce (Lactuca sativa).

Leafy green production in high tunnels (HTs) results in increased yields, improved visual quality, and extended production with polyethylene (poly) film and/or shade cloth coverings. However, altering visible and ultra-violet light with HT coverings may reduce phytochemicals, thus influencing plant pigmentation and taste. The objective of this study was to examine various HT coverings on the sensory perceptions, soil temperature, color, and anthocyanin accumulation of red leaf lettuce. The coverings included standard poly, standard poly with removal two weeks prior to harvest (movable), diffuse poly, clear poly, UV-A/B blocking poly (block), standard poly with 55% shade cloth, and the open field. A highly trained descriptive panel evaluated the samples using a scale from 0 (none) to 15 (extremely high) and determined a list of 20 sensory attributes. The color intensity attribute had the most differentiation between coverings, and the open field was higher (i.e., darker) than the others at 7.5 (p < 0.0001), followed by clear and movable coverings at 6.8, and the shade covering scored a 2. Strong relationships existed between both colorimetric (hue°) and anthocyanin analysis to panelist-based scores (R2 = 0.847 and 0.640, respectively). The initial crispness was similar for movable, standard, diffuse, and block coverings at 5.3 on average, which was higher than the open field at 4 (p < 0.01). The open field lettuce grew under cooler soil temperatures, which may have slowed down maturation and resulted in softer tissue. Based on this study, HT growers can implement specific coverings to cater to markets that value visual quality.

Effects of Fertilizer Source and Rate on Zinnia Cut Flower Production in a High Tunnel

Sustainable nutrient management in high tunnel production is critical for optimizing crop yield and quality and improving soil health. In this study, we investigated the influence of different pre-plant composts (composted broiler litter, vemicompost, and cotton gin compost) in combination with different rates of organic or conventional fertilizer on zinnia plant growth, marketable yield of cut flower stems (&gt;30 cm), and soil nutrients in a high tunnel over two years. Results showed that in general, pre-plant compost influenced plant growth, and plants that received composted broiler litter had the highest plant growth index. However, pre-plant compost did not affect the number of marketable cut stems. Fertigation during the growing season influenced the number of marketable cut stems. Comparable rates of nitrogen, from either organic or conventional fertilizer, produced similar numbers of marketable stems, suggesting that the organic fertilizer used in this study can be used as a fertilizer source for the production of zinnia cut flowers. After two years of production under the high tunnel, soil-extractable phosphorus, sodium, zinc, and pH significantly increased, suggesting that salt accumulation should be closely monitored in response to different compost or fertilizer sources with long-term production under high tunnels.

High Tunnel Production of Containerized Hybrid and Heirloom Tomatoes Using Grafted Plants with Two Types of Rootstocks

Tomatoes (Solanum lycopersicum) are not only one of the most widely grown and consumed vegetables in the U.S., but are also one of the most economically important vegetables for Mississippi growers operating on small- to medium-sized farms. High tunnel production and vegetable grafting serve as effective approaches to provide season extension and improve productivity and resistance to a number of abiotic and biotic factors for tomato plants. Six tomato cultivars, including three hybrids (‘Big Beef’, ‘Early Girl’, and ‘Sun Sugar’) and three heirlooms (‘Brandywine’, ‘Mortgage Lifter’, and ‘San Marzano’), were evaluated for plant growth, fruit yield, and quality in a containerized high tunnel production system in 2020. Each cultivar was grafted onto two types of interspecific hybrid rootstocks ‘Emperador’, or ‘Maxifort’, or grown non-grafted as control. ‘Big Beef’ and ‘Early Girl’ produced comparable highest marketable yields of 9.62 to 11.12 kg per plant, compared with ‘San Marzano’ and ‘Sun Sugar’ producing the lowest marketable yields of 3.27 to 4.76 kg per plant due to small fruit sizes. Grafting the selected tomato cultivars with the two rootstock types did not alter total marketable yield of any cultivar, but affected overall stem diameter, fruit color, and β-carotene concentrations. The rootstock ‘Emperador’ decreased soluble solids content and titratable acidity in ‘Early Girl’ compared to ‘Maxifort’ grafted or non-grafted plants. The high tunnel enabled early transplanting and resulted in advanced tomato harvest by approximately three to four weeks compared to local field production.

Impact of Shade and Fogging on High Tunnel Production and Mineral Content of Organically Grown Lettuce, Basil, and Arugula in Georgia

This study evaluated the impact of shade cloth and fogging systems on the microclimate at the plant canopy level and yield of basil (Oscimum basilicum L.), arugula (Eruca vesicaria subsp. Sativa L.), and lettuce (Lactuca sativa L.) planted in mid-September and early October in high tunnels. Fogging systems were installed at canopy level in plots within shaded (30%) and non-shaded high tunnels. Average air temperatures in the shaded high tunnels were 0.9 °C lower than non-shaded high tunnels during the day. Shade cloth significantly reduced soil temperatures during the day and night periods by 1.5 °C and 1.3 °C, respectively, compared to non-shaded treatments. Fogging systems did not have an impact on air temperature, soil temperature, or relative humidity, but did increase canopy leaf wetness. Shade and fogging did not impact the yield of any of the crops grown. Yield was impacted by planting date, with earlier planting result in higher yields of lettuce and basil. Yields for arugula were greater during the second planting date than the first. Planting date and shade cloth interacted to affect the concentrations of macronutrients.

Economic Analysis of Growing Grafted Cucumber Plants for High Tunnel Production

Cucumber (Cucumis sativus) is one of the most important vegetables produced and consumed in the United States. In the midwestern United States, a major obstacle to spring cucumber production is low soil temperatures during plant establishment. High tunnel is a popular tool for season extension of vegetable production. Low soil temperature is a challenge for cucumber production even inside high tunnels. Grafting is a cultural practice known to help control soilborne diseases and improve plants’ tolerance to abiotic stresses. Recent studies found that using grafted cucumber plants with cold-tolerant rootstocks greatly benefited early-season seedless cucumber production in high tunnels. The objective of this study was to analyze the economic feasibility of growing grafted cucumber in high tunnels. A comparison of partial costs and returns between growing grafted and nongrafted cucumbers in a high tunnel in Vincennes, IN, was conducted. Data were used to develop a partial budget analysis and sensitivity tests. Data included production costs, marketable yield, and price of cucumber through different market channels. This study provided a baseline reference for growers interested in grafting seedless cucumber and for high tunnel production. Although costs of grafted transplants were higher, their yield and potential revenue helped to offset the higher costs. Results indicated that grafting can help farmers increase net returns through the increasing yield of grafted plants. Results from the sensitivity analysis illustrated how the increased yield of grafted cucumbers offsets the extra cost incurred in the technique while providing a higher revenue. While actual production costs for individual farmers may vary, our findings suggested that grafting can be an economically feasible tool for high tunnel seedless cucumber production.

The role of grafting for local tomato production in high tunnels

The role of grafting for local tomato production in high tunnels

Impact of Farm Management Practices on Downy Mildew Disease of Cucumber in High Tunnels

Downy mildew of cucumber caused by Pseudoperonospora cubensisis is a serious threat to the cucurbits production in high tunnels. In this study, the disease incidence and severity were recorded from nine high tunnel farms, located at Vehari District, Pakistan. The results revealed that downy mildew incidence was ranged from 24 to 80%. The disease development was correlated with plant genotype, sowing time, commonly used fungicides, and plant growth stages. "Kaan" was the most resistant while "Yayla" was the highly susceptible plant genotype against the disease. Cucumber sowing at mid-November showed significantly less disease over early and late sowing. Flowering was the most vulnerable stage of plants for disease development. ‘Champion’ (Copper hydroxide) followed by ‘Score’ (Difenoconazole) fungicides reduced the disease to 55% and 43%, respectively, which increased the yield 8-15 %. We conclude that the use of resistant genotype “Kaan”, protectant fungicide ‘Champion’ and appropriate sowing time Mid-November may reduce the disease incidence appreciably in high tunnels.

High Tunnel Production of Tomatoes for Season Extension in Southeast Alabama

A series of experiments was conducted to evaluate variety selection and planting date for spring and fall season extension of tomato (Solanum lycopersicum L. (syn.: Lycoperisicon esculentum Mill.)) production in high tunnels in southeast Alabama. ‘BHN 640’, ‘Florida 91’, ‘Sun Leaper’, and ‘Carolina Gold’ were evaluated for early spring production in 2004. These varieties did not differ in total yield of marketable fruit; however, ‘BHN 640’ and ‘Sun Leaper’ produced higher early yields compared with the other varieties. ‘BHN 640’ and ‘Florida 91’ were evaluated for late-season extension in fall 2004. ‘BHN 640’ produced higher yields of large, medium, total marketable, and unmarketable fruit grades than ‘Florida 91’. In a study conducted in early 2005, higher yields of marketable fruit were produced from the first planting date (31 January) compared with the final of four planting date (25 Mar.). In summary, results indicated that season extension of tomato production in high tunnels was possible, with harvests three weeks earlier in the spring and 12 weeks later in the fall compared with typical field harvest dates. These early yields can command prices from $3.30 to $4.40US per kg of fruit.

Pulsed Water Mists for Suppression of Strawberry Powdery Mildew.

Powdery mildew (Podosphaera aphanis) is a destructive and widespread disease of strawberry (Fragaria × ananassa), especially when susceptible cultivars are grown in high plastic tunnels or glasshouses. Many powdery mildews thrive in humid environments but free water films on plant surfaces can inhibit conidial germination of some species. We hypothesized that P. aphanis might be directly suppressed by rain through the action of water films and meteoric water. In repeated experiments, the hydrophobic conidia of P. aphanis collected on the surface of water droplets, resulting in their removal when the droplets rolled over the leaf surfaces and fell to the ground. Meteoric water and water films also damaged conidiophores. Brief midday water mists applied in pulses lasting 1 min each four times per day were as effective as multiple fungicide treatments in suppressing powdery mildew. Rapid drying of the pulsed mists resulted in effective suppression of powdery mildew without consequent increases of fungal pathogens that might benefit from water films. The timing and duration of water sprinkling has been refined to the point where it can provide a commercially relevant degree of suppression of powdery mildew on strawberry in a high-tunnel production system.

Effects of Within-row Intercropping with Snow Peas on Yield and Quality of Cherry Tomatoes in an Organic High Tunnel Production System

Intercropping can increase land use efficiency in high tunnel crop production, but it may also lead to decreases in yield and quality of main crops due to the potential competition for resources. This study evaluated the agronomic viability of intercropping snow pea (Pisum sativum L., ‘Ho Lan Dou’) with cherry tomato (Solanum lycopersicum L. var. cerasiforme ‘Sarina hybrid’) without additional inputs of water and fertilizers on peas in an organic high tunnel production system under Southern Ontario climate conditions in Guelph, Ontario, Canada (lat. 43.5 °N, long. 80.2 °W) during 2015 and 2016. In each 80-cm-wide bed, the tomato crops were planted alternately in double rows spaced 30 cm apart, with in-row spacing of 110 cm, which resulted in a planting density of ≈24,000 plants/ha. The snow pea seeds were sown between the tomato plants (i.e., within the same beds as tomatoes) in holes (two seeds per hole), with four rows in each bed and in-row holes spaced 10 cm and at least 25 cm away from the tomato plants, which resulted in a seeding rate of ≈650, 000 seeds/ha. The same amount of water or fertilizer was applied to the intercropping and nonintercropping plots based on the needs of the cherry tomato plants. Plant growth, fruit yield, and quality were compared between tomato plants with and without intercropping. Intercropping with snow peas did not affect total marketable fruit yield, unmarketable fruit percentage, fruit quality traits (e.g., individual fruit weight, soluble solids content, dry matter content, and postharvest water loss), or early-stage plant growth of the cherry tomato. Therefore, it is at least an agronomical possibility to intercrop snow peas with cherry tomatoes on the same beds without additional inputs of water and fertilizer on snow peas in an organic high tunnel system. The additional yield of pea shoots or pods in the intercropping treatment also increased economic gross returns in the high tunnels, although the economic net return might vary with the costs of seeds and labor involved in snow pea growing.

High-Tunnel Production of Strawberries Using Black and Red Plastic Mulches

High tunnels are economical season extension tools for strawberry (Fragaria × ananassa) growers in nonmajor strawberry producing states in the United States (US), where grower competitiveness can be increased by off-season crop production. Six June-bearing (“Camarosa”, “Camino Real”, “Chandler”, “Fronteras”, “Sensation”, and “Strawberry Festival”) and two day-neutral (“Albion” and “San Andreas”) strawberry cultivars were transplanted on 18 November 2017 and evaluated for their growth, yield, quality, and time of fruit harvest in a high-tunnel production system in Mississippi (US Department of Agriculture (USDA) hardiness zone 8a) during one growing season from fall 2017 to spring 2018. Effects of black and red plastic mulches were compared in producing strawberries. The high tunnel raised daily air temperatures, provided frost protection, and resulted in advanced fruit harvest by 4–6 weeks compared to local field production with the first ripe fruit produced in early March. “Camino Real”, “Chandler”, and “Strawberry Festival” produced similar highest total marketable yields of 483 g to 559 g per plant, with “Sensation” producing the lowest marketable yield of 215 g per plant. Red mulch decreased marketable yield in March but increased it in May compared with black mulch. Mulch type did not affect plant vegetative growth or strawberry fruit quality variables including berry size, soluble solid content, total phenolic content, or total anthocyanin content.

Reducing postharvest food losses in organic spinach with the implementation of high tunnel production systems

Fresh produce constitutes 44% by weight of the global food losses and waste. Postharvest losses of fresh produce are closely related to the preharvest field conditions during growth. In the Central US, many small acreage vegetable growers are utilizing high tunnels, which have been successful in increasing the yield of several crops. Little is known about the effect of this production system on the postharvest losses. This study tested the hypothesis that the production system will affect the postharvest losses of organic spinach (Spinacia oleracea, “Corvair”) when stored at 3 or 13 °C. Comparative open field and high tunnel trials were conducted from 2015 to 2017. Postharvest losses were evaluated with regard to the spinach quality characteristics and shelf life. During storage at 3 °C, there were no major quality differences between the spinach grown in the two production systems. During storage at 13 °C, in both years, spinach grown in the high tunnels had 1.2 to 2.3% higher water content than spinach grown in the open field. In the second year, high tunnel spinach stored at 13 °C had a lower respiration rate (P < 0.05) and a slower rate of yellowing as indicated by higher chlorophyll content (P < 0.001), significantly lower lightness values, and significantly higher hue values than open field spinach. The high tunnel spinach demonstrated longer shelf life in year 1 and higher quality towards the end of storage in year two when compared to open field spinach when stored at 13 °C. This is the first study to examine the effect of the high tunnel production system on the postharvest quality and losses of spinach. Our results indicate that high tunnels can reduce the postharvest food losses of spinach when stored at 13 °C, due to increased water content and decreased senescence rate.