Introduction
Muskmelon (Cucumis melo) is an important warm season cucurbit (Cucurbitaceae) for diversified vegetable growers because of its popularity with consumers and relatively high value (Thakur, Sharma and Thakur, Reference Thakur, Sharma and Thakur2019). Organic muskmelon production is important for New York (NY) state growers, whose organic vegetable sales approximate $28.3 million annually (USDA NASS, 2022). In NY, muskmelons are usually established by transplanting seedlings into plastic-covered raised beds in mid-June, and harvest occurs approximately 60–65 days later. Despite recent advances toward closing the yield gap between conventional and organic cucurbit production (Nair and Ngouajio, Reference Nair and Ngouajio2010; Ponisio et al., Reference Ponisio, Gonigle, Macem, Palomino, De Valpine and Kremen2015), major challenges in organic muskmelon production persist, often related to the management of pests, diseases, and weeds under organic standards (Skidmore et al., Reference Skidmore, Wilson, Williams and Bessin2019). The multiple abiotic and biotic stresses affecting muskmelon necessitate a systems approach to ensure the optimization of organic production (Ikerd, Reference Ikerd1993).
The most important insect pests affecting muskmelon production in NY include striped (Acalymma vittatum) and spotted (Diabrotica undecimpunctata howardi) cucumber beetles (Cline et al., Reference Cline, Sedlacek, Hillman, Parker and Silvernail2008; Haber et al., Reference Haber, Wallingford, Grettenberger, Ramirez Bonilla, Vinchesi-Vahl and Weber2021), squash bugs (Anasa tristis; Palumbo, Fargo and Bonjour, Reference Palumbo, Fargo and Bonjour1991; Doughty et al., Reference Doughty, Wilson, Schultz and Kuhar2016), and squash vine borer (Melittia cucurbitae; Middleton Reference Middleton2018). In the United States, management of cucumber beetles in cucurbit production has been estimated to cost $100 million annually (Schroder, Martin and Athanas, Reference Schroder, Martin and Athanas2001). Cucumber beetles and squash bugs are also vectors of plant-pathogenic bacteria that cause serious, often fatal diseases of cucurbits (Bruton et al., Reference Bruton, Mitchell, Fletcher, Pair, Wayadande, Melcher, Brady, Bextine and Popham2003; Saalau Rojas et al., Reference Saalau Rojas, Batzer, Beattie, Fleischer, Shapiro, Williams, Bessin, Bruton, Boucher and Jesse2015). Cucumber beetles transmit the xylem-limited Gram-negative bacterium, Erwinia tracheiphila, which causes bacterial wilt (Ellers-Kirk and Fleischer, Reference Ellers-Kirk and Fleischer2006). Symptoms of bacterial wilt usually begin as rapid wilting, followed closely by foliar necrosis and plant death; however, symptom progress varies among cucurbit species and cultivars (Hoffmann, Ayyappath and Kirkwyland, Reference Hoffmann, Ayyappath and Kirkwyland2000; Saalau Rojas et al., Reference Saalau Rojas, Batzer, Beattie, Fleischer, Shapiro, Williams, Bessin, Bruton, Boucher and Jesse2015). E. tracheiphila is transmitted when cucumber beetles feed on infected plants and deposit frass in fresh feeding wounds on leaves or flower nectaries (Mitchell and Hanks, Reference Mitchell and Hanks2009; Sasu et al., Reference Sasu, Seidl-Adams, Wall, Winsor and Stephenson2010). Moreover, E. tracheiphila can also overwinter within adult striped cucumber beetles and, therefore, contribute primary inoculum for crops in the subsequent year (Ellers-Kirk and Fleischer, Reference Ellers-Kirk and Fleischer2006). The pathogen causes disease by multiplying within the xylem and producing polysaccharides, which interfere with water transport through vascular occlusion (Sasu et al., Reference Sasu, Seidl-Adams, Wall, Winsor and Stephenson2010; Saalau Rojas et al., Reference Saalau Rojas, Dixon, Batzer and Gleason2013, Reference Saalau Rojas, Batzer, Beattie, Fleischer, Shapiro, Williams, Bessin, Bruton, Boucher and Jesse2015). In addition, cucumber beetle larvae can kill seedlings by burrowing into roots, and feeding by adults can scar rinds of mature fruit (Michelbacher, Middlekauff and Bacon, Reference Michelbacher, Middlekauff and Bacon1953).
Squash bugs vector the Gram-negative bacterium, Serratia marcescens, which causes cucurbit yellow vine disease (CYVD; Bruton et al., Reference Bruton, Mitchell, Fletcher, Pair, Wayadande, Melcher, Brady, Bextine and Popham2003; Rascoe et al., Reference Rascoe, Berg, Melcher, Mitchell, Bruton, Pair and Fletcher2003). In NY, CYVD is a newly reported and emerging disease of cucurbit (Rodriguez-Herrera et al., Reference Rodriguez-Herrera, Ma, Swingle, Pethybridge, Gonzalez-Giron, Herrmann, Damann and Smart2023). CYVD-affected plants appear stunted and chlorotic, and rapidly wilt and/or decline, usually dying around 2 weeks before harvest. However, squash bugs also cause direct crop loss by sucking the sap from the foliage resulting in chlorotic patches and wilting (Doughty et al., Reference Doughty, Wilson, Schultz and Kuhar2016). The symptoms of bacterial wilt and CYVD are often easily confused between each other and with other diseases, such as Fusarium crown rot (Brust, Reference Brust1997, Reference Brust2007; Thakur, Sharma and Thakur, Reference Thakur, Sharma and Thakur2019).
In conventional (non-organic) muskmelon production, control of cucumber beetles and bacterial wilt relies on synthetic insecticides (Sharma, Rana and Shiwani, Reference Sharma, Rana, Shiwani and Pessarakli2016; Haber et al., Reference Haber, Wallingford, Grettenberger, Ramirez Bonilla, Vinchesi-Vahl and Weber2021). However, a substantial constraint on organic muskmelon production is achieving acceptable pest control through integrated management practices (Snyder, Reference Snyder2012). Pesticides listed by the Organic Materials Review Institute (OMRI) for use in organic production often suffer from suboptimal efficacy for systems-level integration and effective control of insect pest populations. In addition, broad-spectrum OMRI-listed insecticides such as pyrethrins may harm populations of beneficial insects, including pollinators, and interfere with the management of other pests (Desneux, Decourtye and Delpuech, Reference Desneux, Decourtye and Delpuech2006; Sharma, Rana and Shiwani, Reference Sharma, Rana, Shiwani and Pessarakli2016). Other pest management options may not be practical. For example, insect-pest repellants, such as kaolin clay, should be applied before insect arrival but can interfere with net development on the muskmelon rind (Haber et al., Reference Haber, Wallingford, Grettenberger, Ramirez Bonilla, Vinchesi-Vahl and Weber2021). Other cultural strategies in cucurbit crops, such as manipulating planting date have shown some promise for managing overwintered squash bug populations in spring crops to avoid early season infestations (Palumbo, Fargo and Bonjour, Reference Palumbo, Fargo and Bonjour1991). Perimeter trap cropping and biochemical lures have been effective for cucumber beetle control in other cucurbits (Cavanagh et al., Reference Cavanagh, Hazzard, Adler and Boucher2009). However, in Iowa field trials, these strategies failed to provide consistent control of cucumber beetles in muskmelon (M. Gleason, unpublished data). There is also little available knowledge on bacterial wilt resistance in various muskmelon genotypes (Acharya et al., Reference Acharya, Mackasmiel, Taheri, Ondzighi-Assoume, Weng and Dumenyo2021).
Exclusion of pests by a physical barrier such as a row cover may be a viable alternative for integration into organic muskmelon production with the potential to decrease pesticide usage and non-target effects (Bextine et al., Reference Bextine, Wayadande, Bruton, Pair, Mitchell and Fletcher2001). Using spunbonded polypropylene fabric in a low tunnel (~0.5 m tall) can protect the seedlings until the foliage outgrows the cover, requiring removal about 3 weeks after transplanting (Minter and Bessin, Reference Minter and Bessin2014; Nelson et al., Reference Nelson, González-Acuña, Nair, Cheng, Mphande, Badilla-Arias, Zhang and Gleason2023). Mesotunnels are a modified row cover system that offers multiple advantages compared to low tunnels (Skidmore et al., Reference Skidmore, Wilson, Williams and Bessin2019; Nelson et al., Reference Nelson, González-Acuña, Nair, Cheng, Mphande, Badilla-Arias, Zhang and Gleason2023). First, they consist of nylon mesh netting established immediately after transplanting to provide pest exclusion for most or the entire growing season. The netting is supported by approximately 1-m-high hoops which provide space for canopy growth. The durable mesh fabric facilitates airflow, mitigating heat build-up as well as extreme-weather damage. The netting also enables foliar pesticide applications without net removal. However, muskmelons are exclusively insect-pollinated (Acharya et al., Reference Acharya, Mackasmiel, Taheri, Ondzighi-Assoume, Weng and Dumenyo2021), so strategies are required to facilitate pollination in a season-long mesotunnel. In a muskmelon field study in Iowa, full season mesotunnels (netting in place all season) supplemented with purchased bumblebee hives, and treatments whose covers were removed during bloom and replaced 2 weeks later, doubled marketable yield compared to non-covered treatments while receiving fewer insecticide sprays and encountering less pest damage and disease incidence (Nelson et al., Reference Nelson, González-Acuña, Nair, Cheng, Mphande, Badilla-Arias, Zhang and Gleason2023). Production system changes also need to consider the impact on other important factors influencing yield, such as foliar diseases. The dominant foliar diseases affecting cucurbit production in NY are powdery mildew caused by the fungus, Podosphaera xanthii (Pérez-García et al., Reference Pérez-García, Romero, Fernádez-Ortuño, López-Ruiz, De Vicente and Torés2009), downy mildew caused by the oomycete, Pseudoperonospora cubensis (Savory et al., Reference Savory, Granke, Quesada-Ocampo, Varbanova, Hausbeck and Day2011), and Alternaria leaf spot caused by the fungus, Alternaria cucumerina. Together the diseases deleteriously affect photosynthetic area, and fruit production and quality of cucurbits, including muskmelon (Pérez-García et al., Reference Pérez-García, Romero, Fernádez-Ortuño, López-Ruiz, De Vicente and Torés2009).
The management of weeds in inter-bed areas is also a major issue affecting organic cucurbit production due to weed-crop competition and contribution to the weed seed bank (Jenkins and Ory, Reference Jenkins and Ory2016; Bruce, Silva and Dawson, Reference Bruce, Silva and Dawson2022). In organic cucurbit production, growers usually resort to multiple cultivations or the placement of black plastic mulches for weed management (Lowry and Brainard, Reference Lowry and Brainard2019). Cover crops and living mulches offer potential for weed management and systems improvement (Teasdale and Mohler, Reference Teasdale and Mohler2000; Brust, Claupein and Gerhards, Reference Brust, Claupein and Gerhards2014). For example, cover crops may have persistent beneficial effects on soil health that are often critically important in organic agriculture. These include a reduction in the need for nitrogenous fertilizers because of increased N fixation (Harris and Ratnieks, Reference Harris and Ratnieks2022), mitigation of within-season soil erosion, enhancement of soil health (Sarrantonio and Gallandt, Reference Sarrantonio and Gallandt2003) through incorporation of organic matter (Luo, Wang and Sun, Reference Luo, Wang and Sun2010), and improved soil structure by reducing bulk density, increased microbial activity, abundance, and diversity (Koudahe, Allen and Djaman, Reference Koudahe, Allen and Djaman2022).
To date, studies evaluating mesotunnels for organic cucurbit production systems have been restricted to the midwestern and southern United States. The goal of this study was to evaluate the suitability of mesotunnels for organic muskmelon production in NY using a systems approach. The first objective was conducted to evaluate the effects of mesotunnels and management of inter-bed areas on insect pest populations, disease, weeds, and muskmelon fruit yield and quality. The second objective was to evaluate pollination strategies for integration into a mesotunnel organic muskmelon production system.
Materials and methods
Experiment 1 (integrated pest management)
Site description and experimental design
One field trial was conducted in 2021 and 2022 on organically certified land at the Gates West Certified Organic Farm of Cornell AgriTech, Geneva, NY (42.52′N, 77.13′W, and altitude 242 m). In each year, the fields were separated from each other by ~50 m of perennial ryegrass and clover mix. The soil type of both fields is mapped as Honeoye silt loam with a soil pH of 7.4. The organic matter was 2.5 and 2.2% for the fields used in 2021 and 2022, respectively. For the previous 2 years in both fields, the crops were Ladino white clover in summer and tall fescue planted in fall as the winter cover crop.
Fields were prepared by tillage through moldboard and chisel plowing on two–three occasions (Table 1). Fertilizer (Allganic Nitrogen Plus [15-0-2; Nutrien Ag Solutions Inc.; Hall, NY]) was broadcast-applied prior to raised bed formation at 359.8 and 336.3 kg ha−1 in 2021 and 2022, respectively. Chicken manure at 477.3 kg ha−1 (5-4-3; Kreher Family Farm; Clarence, NY) and 560.4 kg ha−1 (5-4-3; Friendly Blends Compost Crumbles, Friendly Blends; Canandaigua, NY) was placed under the raised beds during formation in 2021 and 2022, respectively. Raised beds (90 cm wide and 10 cm high) were established for single rows of plants with 2.1 m centers and covered by 1 mm thick black plastic mulch (Poly Plastic Products of Sigma Plastics Group; Delano, PA). Irrigation was provided to the muskmelon plants as required for optimal plant growth by a centrally placed drip line with emitters spaced at 30 cm intervals (Empire Drip Supply; Williamson, NY) under the plastic mulch installed during bed preparation. The width of the inter-bed area was 0.9 m. In 2022, a Saukville cultivator (Saukville Tractor; Newburg, WI) with s-tines was used to smooth the soil in the inter-bed area (Table 1).
Timeline of field operations and data collection for experiments 1 (integrated pest management) and 2 (pollination) in organic muskmelon at Geneva, New York
* Field operations included application of fertilizer (broadcast and disked) and raised bed formation including additional fertilizer and irrigation line placement under the bed.
† Not conducted.
Non-treated muskmelon ‘Athena’ seeds (Seedway; Hall, NY) were seeded in an organic seed germination mix (Sprout Island Organic Seed Starter, Coast of Maine; Portland, ME) in 50 cell trays (Griffin Greenhouse Supplies Inc.; Auburn, NY) and grown in an organically certified greenhouse at 20–22°C for 14–17 days. Seedlings were hardened in a cold frame and protected from insect pests by 0.1 cm × 0.1 cm white nylon mesh netting (ExcludeNet; Tek-Knit Industries, Mount Royal, Quebec, Canada) before transplanting into the field in single rows with an in-row spacing of 61 cm (Table 1). In 2021, seedlings were transplanted with a Rain-Flo Vegetable Transplanter (Model 1400; Rain-Flo Irrigation; East Earl, PA), whereas in 2022, seedlings were transplanted by hand due to wet soil conditions preventing tractor access (Table 1).
The experimental design was a randomized complete block with four replications of each single factor (treatment). Experimental plots consisted of three adjacent 9.1-m-long rows with 3-m-long buffer areas separating the ends of the plots lengthwise and one raised, non-planted bed separating adjacent blocks laterally. The total number of plants within each experimental plot was therefore 51 (three rows of 17 plants each). Data were collected from the middle row of each experimental plot. The treatments were: (i) inter-bed area covered with landscape fabric (Empire Drip Supply; Williamson, NY) in a mesotunnel (herein referred to as ‘landscape fabric mesotunnel’); (ii) inter-bed area containing a ryegrass/white clover cover crop in a mesotunnel (‘ryegrass/white clover mesotunnel’); (iii) inter-bed area containing ryegrass only in a mesotunnel (‘ryegrass mesotunnel’); and (iv) landscape fabric covering the inter-bed without a mesotunnel (‘non-covered’; Table 2). Of these treatments, the non-covered treatment was considered the grower standard practice control. The cover crops were seeded 24–31 days before transplanting the muskmelon seedlings (Table 1). The ryegrass/clover inter-bed area was seeded by hand-spreading at 11.2 kg ha−1 annual ryegrass (Lakeview Organic Grain; Penn Yan, NY) and 12.2 kg ha−1 white clover cv. Alice (Fedco Seeds; Clinton, ME). The ryegrass only inter-bed area was seeded by hand-spreading seed at 22.4 kg ha−1 (Lakeview Organic Grain; Penn Yan, NY).
Effect of a season long mesotunnel and inter-bed area management in experiment 1 on striped (A. vittatum) and spotted (D. undecimpunctata howardi) cucumber beetle and squash bug (A. tristis) cumulative populations in organic muskmelon at Geneva, New York, in 2021 and 2022
* Landscape fabric mesotunnel, inter-bed area covered with landscape fabric in a mesotunnel; Ryegrass/white clover mesotunnel, inter-bed area containing a ryegrass/white clover cover crop in a mesotunnel; Ryegrass mesotunnel, inter-bed area containing ryegrass only in a mesotunnel; and Non-covered, landscape fabric covering the inter-bed area without a mesotunnel.
† Populations were counted within five 1 m−2 quadrats located every 1.8 m within the center row during 45-s observation periods and summed across observations (Table 1).
‡ LSD, least significant difference (P = 0.05). Treatments in the same column separated by different letters indicate a significant difference.
§ Probability values <0.05 were significant.
After muskmelon transplanting, mesotunnels were established in the relevant treatments by placing conduit hoops every 2.1 m in a zig-zag pattern (Fig. 1a). Conduit hoops were created by bending 3.1-m long galvanized metal 2.5 cm diameter conduit with a trailer-hitched bender (QuickHoops™ Low Tunnel Bender; Johnny's Selected Seeds, Fairfield, ME). The 0.1 × 0.1 cm white nylon mesh (ExcludeNet; Tek-Knit Industries, Mount Royal, Quebec, Canada) was cut to 12.1 m × 7.9 m pieces, stretched across the entire width of the three row plots by hand, and the edges were secured to the ground with sandbags at 1.5–3.0 m intervals (Fig. 1b) and remained in place until harvest (Fig. 1c). In 2022, the OMRI-listed herbicide, AXXE (13% v/v; BioSafe Systems; East Hartford, CT) was applied to weeds in the areas between plots within rows on June 14 and July 27. Herbicides were not used in 2021.
Establishment of 1-m high mesotunnels for organic muskmelon production involving (a) the use of raised black plastic beds and conduit hoops to support the 0.1 cm × 0.1 cm nylon mesh exclusion netting; (b) nylon mesh stretched over three rows with landscape fabric in the inter-bed areas for weed management and the exclusion netting held down with sandbags; and (c) plant canopy in the mesotunnels approaching muskmelon harvest.
To facilitate pollination in the mesotunnel treatments, a single hive of buff-tailed bumblebees (Bombus terrestris) (Natupol, Koppert Biological Systems Inc.; Howell, MI) was placed in the center of each plot at the first appearance of female flowers (Table 1). Each hive was placed on rocks and covered by a plastic laundry basket to protect against rain and sunlight but provided ventilation through holes on the sides. Row cover ends were closed immediately after the hives were inserted, and flight holes were positioned parallel to the crop rows. Each hive was provided with a sugar solution (Attracker; Koppert Biological Systems Inc.; Howell, MI) and placed above a water moat (rectangular bin and platform) so ants and other insects would not infest the hive or sugar solution. The sugar solution was checked weekly and refilled when necessary.
Sampling and data collection
Regular assessments of pest populations and disease incidence were made throughout the growing seasons (Table 1). Bacterial wilt was confirmed in symptomatic plants by the presence of bacterial ooze streaming from vascular tissues of cut stems in the field, indicating vascular occlusion by E. tracheiphila (Saalau Rojas et al., Reference Saalau Rojas, Batzer, Beattie, Fleischer, Shapiro, Williams, Bessin, Bruton, Boucher and Jesse2015). The incidence of bacterial wilt and other foliar diseases was evaluated on five plants per plot, each separated by 1.8-m intervals, within the center row of each plot. The foliar diseases evaluated were powdery mildew, downy mildew, and Alternaria leaf spot. The presence of powdery and downy mildew was confirmed by examining potential symptoms for signs of each pathogen at low magnification. Isolations were made from Alternaria leaf spot-like lesions from 30 leaves collected at mid-season and harvest. Leaves were stored at room temperature for up to 48 h before placement in individual glass Petri dishes on fiberglass mesh suspended within sealed plastic trays that contained damp tissue to maintain high humidity. Trays were incubated at 20–22°C and observed for fungal growth after 5 days at low (40×) magnification. Conidia were transferred to potato-dextrose agar (Hardy Diagnostics, Santa Maria, CA) and isolates were identified based on morphological characteristics (Woudenberg et al., Reference Woudenberg, Truter, Groenewald and Crous2014). Epidemic progress for each disease was quantified by calculating the area under the disease progress curve (AUDPC; Madden, Hughes and van den Bosch Reference Madden, Hughes and van den Bosch2007). On each observation, populations of striped and spotted cucumber beetles, squash bugs, squash vine borer, and aphids were counted in five 1 m−2 quadrats permanently located every 1.8 m within the center row during 45-s observation periods on dates outlined in Table 1.
Temperature and relative humidity were measured every 15 min using a Model H5179 Govee Wi-Fi thermometer hygrometer (Shenzhen Intellirocks Tech. Co., Ltd.; Nanshan District, Shenzhen, China). One sensor was placed in the center of each plot within two arbitrarily selected experimental blocks. The sensor was placed 50 cm above the raised bed under a plastic shield for rain protection. Data were collected weekly during most of the growing season in each year (Table 1).
At harvest, biomass of weeds and cover crops in the inter-bed area was sampled in five arbitrarily selected 0.25 m−2 quadrats per plot by clipping all plants at the soil line and separating them into cover crop or weeds (Table 1). The fresh weight of weeds and cover crops was recorded, and the predominant weed species were identified. Weed and cover crop material were then dried at 60°C for 5 days to calculate the dry weight per plot.
Individual fruit from the entire center row of each plot were harvested, graded, and weighed according to USDA commercial standards (USDA AMS, 2008) on two or three occasions in each year (Table 1). At the first and/or second harvests of each year, only ripe fruit was removed, whereas at the final harvest, all fruit were removed. Defects (⩾5% of the surface) that classified fruit as non-marketable included cracked, dented, immature, misshapen, moldy, poor net development, rodent damaged, and soft (USDA AMS, 2008).
Experiment 2 (pollination)
Site description and experimental design
A field trial evaluating pollination treatments in mesotunnel-grown muskmelon was conducted in 2021 and 2022 on organically certified land at the Gates West Certified Organic Farm of Cornell AgriTech, Geneva, NY. The trials were in different fields in each year and separated by ~50 m of perennial ryegrass and clover mix. Field trials within experiment 2 were separated from experiment 1 by approximately 200 m each year. The soil type of these fields was also Honeoye silt loam with a soil pH of 7.5. Organic matter was 2.6 and 2.5% for the fields used in 2021 and 2022, respectively. For the previous 2 years in each field, the summer crop was alfalfa, and tall fescue was planted each fall as a winter cover crop.
Fields were prepared using the same operations and fertilizer inputs, and raised beds were established in the same manner as described for experiment 1 (Table 1). Landscape fabric (Empire Drip Supply; Williamson, NY) was used to cover the areas between beds for weed management. Seeds of muskmelon ‘Athena’ (Seedway; Hall, NY) were from the same seed lot used for experiment 1. Seedlings were hardened in a cold frame under 0.1 cm × 0.1 cm nylon mesh netting (ExcludeNet; Tek-Knit Industries, Mount Royal, Quebec, Canada) before transplanting into the field with an in-row spacing of 61 cm. After transplanting, mesotunnels were established over all experimental plots using 48.8 m × 7.9 m pieces of 0.1 cm × 0.1 cm nylon mesh netting stretched across all three rows in each plot. Irrigation was provided through the drip line under the raised beds for plant growth as needed.
The experimental design was a randomized complete block with four replications of each treatment. Plots were three rows wide and 45.7 m long with the same within- and between-row dimensions used for experiment 1. The total number of plants within each experimental plot was 225 (75 plants in each of the three rows). Data were collected from the middle row of each plot. Treatments were: (i) removal of the netting at flowering followed by a replacement after 3 weeks and final removal at first harvest (‘on/off/on’); (ii) opening the tunnel ends for 3 weeks during flowering (‘open ends’); and (iii) tunnels enclosed by the netting from transplant until harvest (‘closed’; Table 1). One end of the plots assigned to the closed treatment was periodically and briefly unsealed to place a buff-tailed bumblebee hive (Natupol, Koppert Biological Systems Inc.; Howell, MI) at the mid-point of each plot in the center row when bloom began. These plots were then accessed on a weekly basis to maintain the sugar solution, Attracker (Koppert Biological Systems Inc.; Howell, MI). In 2022, the hives were removed for 24 h on July 20 for an insecticide application to control aphids (Supplementary Table 1). The on/off/on treatment served as the grower standard practice control in this experiment. The open ends treatment was included as having potential for reduced labor costs in netting management while providing pollinator access and some protection to damage from insect pests. Plots were scouted on a weekly basis and OMRI-listed pesticides were applied as necessary to minimize crop loss from pest damage and foliar diseases, using an air blast sprayer (1400 L ha−1; UniGreen Spraying Equipment; Visalia, CA; Supplementary Table 1).
Sampling and data collection
Regular assessments were made for insect pest populations and disease incidence as described for experiment 1 (Table 1). Pollinator populations (bumblebees and other pollinators) and male and female flowers were counted at 3–4 day intervals for 2 weeks over flowering (Table 1). Flowers were counted as an early indicator of resource allocation for fruit growth (Gao et al., Reference Gao, Yu, Li, Li and Peng2021). Each assessment was conducted at 9 am within a 45-s scan of a 1 m−2 quadrat every 2.5 m in the center row and totaled per plot. For treatment evaluation, fruit were picked from the entire center row of each plot. Only ripe fruit were removed during the initial harvest, but all fruit, irrespective of maturity, were removed at the final harvest (Table 1). Individual fruit were weighed and graded according to USDA commercial standards (USDA AMS, 2008) and summarized as described for experiment 1.
Statistical analyses
Data common to both experiments were insect pest populations, disease incidence and epidemic progress (bacterial wilt, powdery mildew, downy mildew, and Alternaria leaf spot), and fruit yield components (number and weight of marketable and non-marketable fruit, and incidence of non-marketable fruit with common defects). For experiment 1, the biomass of weeds and cover crops was also evaluated. For experiment 2, pollinator populations and flower numbers were also counted. Exploratory data analysis was conducted to evaluate the differences among the means between datasets from common experiments using the Anderson–Darling goodness-of-fit test (Anderson and Darling, Reference Anderson and Darling1954) and non-homogeneous variances using the Fisher F-test (Markowski and Markowski, Reference Markowski and Markowski1990). As significant differences in means and the homogeneity of variances were detected between the replication of each experiment, the effects of treatments from the experiments conducted in each year were therefore analyzed separately using generalized linear modeling with treatment and replication as a fixed effect and random effect, respectively. Multiple post-hoc comparisons were conducted using the Fisher's least significant difference test (P = 0.05). Analyses were conducted with Genstat (Version 17.2; VSN International, Hemel Hempstead, UK).
Results
Experiment 1
Cucumber beetle populations were relatively low in both years, with striped beetles predominant over spotted beetles. At harvest, the population of cucumber beetles was <1 m−2 in the mesotunnel treatments (Figs. 2a and 2b; Table 2). Cucumber beetle populations were reduced in mesotunnel treatments compared to the non-covered by 98.5 and 97.9% in 2021 (Fig. 2a) and 2022 (Fig. 2b), respectively, and were not significantly different among plots with mesotunnel irrespective of inter-bed area management (Table 2). Squash populations were also significantly reduced in plots with mesotunnels compared to the non-covered (Table 2). The incidence of bacterial wilt in non-covered plots was greater in 2021 than in 2022 (Figs. 2c and 2d; Table 3). In both years, bacterial wilt epidemic progress (AUDPC) was significantly affected by treatment (Table 3). In 2021, bacterial wilt AUDPC was lower in all mesotunnel treatments than in non-covered plots by an average of 33.7% but was not different among mesotunnel treatments (Table 3). Similarly in 2022, bacterial wilt incidence and AUDPC were greater in the non-covered than in the mesotunnel treatments, in which no bacterial wilt was observed (Table 3).
Progress curves for striped (Acalymma vittatum) and spotted (Diabrotica undecimpunctata howardi) cucumber beetle populations in 2021 (a) and 2022 (b), and bacterial wilt caused by Erwinia tracheiphila in 2021 (c) and 2022 (d) in experiment 1 for organic muskmelon production in Geneva, New York. Values are the means across plots within treatments and the bars represent the standard error.
Effect of a season long mesotunnel and inter-bed area management in experiment 1 on the final incidence and epidemic progress of powdery mildew (caused by P. xanthii), Alternaria leaf spot (A. cucumerina), and bacterial wilt (E. tracheiphila) in organic muskmelon at Geneva, New York, in 2021 and 2022
* Landscape fabric mesotunnel, inter-bed area covered with landscape fabric in a mesotunnel; Ryegrass/white clover mesotunnel, inter-bed area containing a ryegrass/white clover cover crop in a mesotunnel; Ryegrass mesotunnel, inter-bed area containing ryegrass only in a mesotunnel; and Non-covered, landscape fabric covering the inter-bed area without a mesotunnel.
† Area under the disease progress curve. The incidence of each disease was evaluated multiple times (Table 1) on plants separated by 1.8-m intervals, within the center row of each plot.
‡ LSD, least significant difference (P = 0.05). Treatments in the same column separated by different letters indicate a significant difference.
§ Probability values <0.05 were significant.
The incidence of powdery mildew and Alternaria leaf spot was high in both years (Table 3). The average incidence of powdery mildew at the final assessment was 97 and 65% in 2021 and 2022, respectively, and this seasonal variation was also reflected in a 134.1% greater AUDPC in 2021 than in 2022. Treatment had no effect on powdery mildew incidence and AUDPC in either year (Table 3). Incidence of Alternaria leaf spot within plots varied between 65 and 95% at the final assessment in 2021 and was 100% in 2022. Isolation frequencies of A. cucumerina associated with necrotic foliar lesions at mid-season and harvest were 76–82 and 92–98% in 2021 and 2022, respectively. Treatment had no effect on the incidence or AUDPC of Alternaria leaf spot in either year (Table 3). Downy mildew was observed only in 2022 at <25% incidence at the final assessment, and incidence and AUDPC were not affected by treatment. Squash bug populations in the non-covered plots at harvest averaged 24 and 4.8 m−2 in 2021 and 2022, respectively, but were significantly lower in all mesotunnel treatments than non-covered plots (Table 2). Cumulative populations of squash vine borer and aphids were <1 m−2 in both years (data not shown).
The most prevalent weeds in the inter-bed areas within the treatments with cover crops were lambsquarters (Chenopodium album), pigweeds (Amaranthus spp.), annual ragweed (Ambrosia artemisiifolia), curly dock (Rumex crispus), purslane (Portulaca oleracea), and dandelion (Taraxacum officinale). In both years, the dry weight of weeds did not differ among cover crop treatments (Table 4). The dry weight of cover crops in 2022 was approximately double that in 2021, but there were no differences among cover crops treatments within either year (Table 4).
Effect of a season long mesotunnel and inter-bed area treatments in experiment 1 on weed and cover crop biomass, and fruit weight and number in organic muskmelon at Geneva, New York, in 2021 and 2022
* Landscape fabric mesotunnel, inter-bed area covered with landscape fabric in a mesotunnel; Ryegrass/white clover mesotunnel, inter-bed area containing a ryegrass/white clover cover crop in a mesotunnel; Ryegrass mesotunnel, inter-bed area containing ryegrass only in a mesotunnel; and Non-covered, landscape fabric covering the inter-bed area without a mesotunnel.
† From the entire middle row of each plot (17 plants).
‡ LSD, least significant difference (P = 0.05). Treatments in the same column separated by different letters indicate a significant difference.
§ Probability values <0.05 were significant.
The mesotunnels modified the air temperature within the canopy in both years (Supplementary Tables 2 and 3). In 2021, average minimum temperatures were similar between the treatments, but average maximum temperatures in June, July, and August were several degree greater in the non-covered plots compared to mesotunnels with either cover crop in the inter-bed area (Supplementary Table 2). In 2022, average temperatures were 3–5°C greater in the landscape fabric mesotunnels compared to other treatments in June, but similar among the treatments in July and August. The average minimum temperatures were 2–3°C greater in the non-covered plots compared to mesotunnels in August, whereas average maximum temperatures were 5–7°C greater in the mesotunnels in June than the non-covered plots. In July and August, this temperature differential was reduced to 2–3°C (Supplementary Table 3). Daily average minimum and maximum relative humidity were similar among the treatments in both years (Supplementary Tables 2 and 3).
Treatment impacted fruit number, marketable fruit weight and number, and non-marketable fruit weight in both years (Table 4). In 2021, marketable fruit weight was an average of 162.3% greater in mesotunnel with landscape fabric plots than the mesotunnels with either cover crop. However, marketable fruit weight was not significantly different between the treatments with landscape fabric irrespective of whether the plots were mesotunnels or non-covered. The weight of non-marketable fruit was also significantly greater in plots with landscape fabric (mesotunnel or non-covered) compared to the ryegrass only mesotunnel. Fruit were classified as non-marketable predominantly from cracks and dents, rodent damage, and softness. Plots with landscape-fabric in the inter-bed area had more cracked fruit than those with cover crops in the inter-bed area, which were not significantly different from each other (Fig. 3a). The incidence of rodent damage was greater in the non-covered plots compared to treatments with a mesotunnel which were not different between each other. The incidence of soft fruit was significantly greater in treatments with landscape fabric in the inter-bed area (mesotunnel or non-covered) and the ryegrass/white clover cover crop than mesotunnels with only ryegrass in the inter-bed area (Fig. 3a).
Radar plots depicting numbers of muskmelon fruit with common defects in experiment 1 at Geneva, New York in (a) 2021 and (b) 2022. Each axis represents defects, and the polygon represents each treatment (green − landscape fabric in the inter-bed area + mesotunnel; orange − ryegrass/white clover in the inter-bed area + mesotunnel; blue − ryegrass only in the inter-bed area + mesotunnel; pink − landscape fabric in the inter-bed area + non-covered). Values along each axis are connected linearly. Dotted lines within the polygons represent the mean values, and the distance between the perimeters represent one standard deviation.
In 2022, marketable fruit weight was significantly greater in mesotunnels with landscape fabric in the inter-bed area than the non-covered plots; but not different between mesotunnels with either cover crop in the inter-bed area (Table 4). The number of marketable fruit was 54.6% greater in the mesotunnels with landscape fabric than other treatments, that were not different from each other. There was no effect of treatment on non-marketable fruit weight and total fruit number (Table 4). The most common defects contributing to non-marketable fruit were poor netting, softening, and immaturity. Treatment had a significant effect on the incidence of unripe and soft fruit (Fig. 3b), which was greater in non-covered plots than mesotunnels with landscape fabric or a ryegrass/white clover cover crop in the inter-bed area (Fig. 3b).
Experiment 2
In both years, cucumber beetle populations were significantly higher in the on/off/on than the open ends and closed treatments, which were not different from each other (Figs. 4a and 4b; Table 5). Bacterial wilt AUDPC was significantly affected by pollination treatment in both years (Table 5). In 2021, bacterial wilt AUDPC was greater in the on/off/on than the open ends treatment but not different from the closed treatment (Fig. 4c; Table 5). In 2022, bacterial wilt AUDPC was greater in the on/off/on and open ends than the closed treatment (Fig. 4d; Table 5). Treatment had no significant effect on the final incidence or epidemic progress of powdery mildew and Alternaria leaf spot in either year (Table 5). Neither squash bugs nor squash vine borer was observed. Low aphid populations were observed in both years but not affected by treatment (P ⩾ 0.319; data not shown).
Progress curves for striped (Acalymma vittatum) and spotted (Diabrotica undecimpunctata howardi) cucumber beetle populations in 2021 (a) and 2022 (b), and bacterial wilt caused by Erwinia tracheiphila in 2021 (c) and 2022 (d) in experiment 2 for organic muskmelon production in Geneva, New York. Values are the means across plots within treatments and the bars represent the standard error.
Effect of netting treatment in experiment 2 on the final incidence and epidemic progress of powdery mildew (caused by P. xanthii), Alternaria leaf spot (A. cucumerina), bacterial wilt (E. tracheiphila), and cumulative striped and spotted cucumber beetle populations in organic muskmelon at Geneva, New York, in 2021 and 2022
* On/off/on, removal of the netting at flowering for 3 weeks followed by replacement until harvest; Open ends, opening the ends of the mesotunnels for 3 weeks during flowering; and Closed, mesotunnels remained closed with a hive of buff-tailed bumblebees placed at the beginning of bloom.
† Disease incidence was evaluated multiple times (Table 1) on plants separated by 1.8-m intervals, within the center row of each plot.
‡ Area under the disease progress curve.
§ Populations were counted within five 1 m−2 quadrats located every 2.5 m within the center row during 45-s observation periods and summed across all observations (Table 1).
∥ LSD, least significant difference (P = 0.05). Treatments in the same column separated by different letters indicate a significant difference.
# Probability values <0.05 were significant.
Pollinators and flower numbers were evaluated for 2 weeks at flowering (Table 6). In both years, bumblebee populations were significantly greater in closed than in open end treatments. In most cases, bumblebee populations were not significantly different between the on/off/on and open ends treatments, except for the first observation week in 2022, where no bumblebees were observed in the open ends (Table 6). Other pollinators (including honey [Apis mellifera] and squash [Peponapis spp. and Xenoglossa spp.] bees) were observed in greater populations in the on/off/on compared to the open ends and closed treatments, in which populations were not significantly different between each other. Hoverfly (multiple genera but not identified) populations were generally low and not different between the treatments in the first observation week in both years. However, in the second week of both years, hoverfly populations were significantly greater in the on/off/on than the open ends and closed treatments, which were not different from each other (Table 6). Flower numbers were not significantly different between the treatments in both observation weeks in 2021. However, in 2022, flower numbers were 59.7 and 133.4% greater in the on/off/on than the closed treatment in the first and second observation weeks, respectively (Table 6).
Effect of netting treatment in experiment 2 on selected pollinator populations and flower numbers in organic muskmelon at Geneva in 2021 and 2022
* On/off/on, removal of the netting at flowering for 3 weeks followed by replacement until harvest; Open ends, opening the ends of the mesotunnels for 3 weeks during flowering; and Closed, mesotunnels remained closed with a hive of buff-tailed bumblebees placed at the beginning of bloom.
† Buff-tailed bumblebee (Bombus terrestris). Others included honeybees (A. mellifera) and squash bees [Peponapis ssp. and Xenoglossa spp.], and hoverflies (multiple genera).
‡ Cumulative flowers from each 1 m−2 quadrat every 2.5 m in the center row per plot.
§ LSD, least significant difference (P = 0.05). Treatments in the same column separated by different letters indicate a significant difference.
∥ Probability values <0.05 were significant.
In both years, pollination treatment had a significant effect on marketable fruit weight and number (Table 7). In 2021, marketable fruit weight was significantly greater in the on/off/on treatment than the other treatments: 20.8 and 64% greater than in the open ends and closed mesotunnels, respectively. Similar trends were observed in 2022, where marketable fruit weight was 640.5% greater in the on/off/on compared to the open ends and closed treatments, and the latter two treatments were not different from each other. The effects of treatment on fruit weight were analogous to those on fruit number. For example, in 2021, marketable fruit number was 20.7 and 60.4% greater in the on/off/on compared to the open ends and closed treatments, respectively, and marketable fruit number in the open ends was 35.8% greater than the closed treatment. In 2022, marketable fruit number was 743.2% greater in the on/off/on compared to the open ends and closed treatments, with these latter two not different from each other. Treatment had no significant effect on non-marketable fruit weight in both years (Table 7).
Effect of netting treatment in experiment 2 on fruit weight and number in organic muskmelon at Geneva, New York, in 2021 and 2022
* On/off/on, removal of the mesotunnel netting at flowering followed by replacement 3 weeks later until harvest; Open ends, opening the ends of the mesotunnels for 3 weeks during flowering; and Closed, mesotunnels remained closed with a hive of buff-tailed bumblebees placed at the beginning of bloom.
† From the middle row of each plot (75 plants).
‡ LSD, least significant difference (P = 0.05); na, not applicable when P > 0.05. Treatments in the same column separated by different letters indicate a significant difference.
§ Probability values <0.05 were significant.
Non-marketable fruit were attributed mainly to rodents, cracks, and mold (Figs. 5 and 6). In 2021, more rodent damaged fruit were in the closed than on/off/on and open ends treatments, whereas the latter treatments did not differ from each other. Significantly more cracked fruit were observed in the on/off/on and closed treatments than in the open ends. The closed treatment had more moldy fruit than the other two treatments, which were not different from each other (Fig. 5). In 2022, there were more immature fruit in the open ends than in the closed or on/off/on treatments (Fig. 6). The incidence of misshapen fruit was significantly greater in the on/off/on treatments than open ends and closed treatments, which were not different from each other. The incidence of moldy fruit was significantly greater in closed tunnels than in the on/off/on and open ends treatments. Moreover, the incidence of soft fruit was also significantly greater in the closed than open ends, but not different from the on/off/on treatment (Fig. 6).
Pie charts depicting muskmelon fruit with common defects in the treatments (open ends, on/off/on, and closed) within experiment 2 in Geneva, New York, in 2021.
Pie charts depicting the number of fruit with selected defects (moldy, cracked/dented, soft, poor net, misshapen, immature/underweight, and rodent damage) in the treatments (open ends, on/off/on, and closed) within Experiment 2 for organic muskmelon production in Geneva, New York, in 2022.
Discussion
Experiment 1
Mesotunnels provided an effective barrier for cucumber beetles and hence significantly reduced the incidence and epidemic progress of bacterial wilt, irrespective of the weed control strategy in the inter-bed area. This finding supports those of other exclusion-netting cucurbit studies in the mid-western United States (e.g., Mueller et al., Reference Mueller, Gleason, Sisson and Massman2006; Nair and Ngouajio Reference Nair and Ngouajio2010; Saalau Rojas et al., Reference Saalau Rojas, Gleason, Batzer and Duffy2011, Reference Saalau Rojas, Batzer, Beattie, Fleischer, Shapiro, Williams, Bessin, Bruton, Boucher and Jesse2015; Minter and Bessin Reference Minter and Bessin2014; Nelson et al., Reference Nelson, González-Acuña, Nair, Cheng, Mphande, Badilla-Arias, Zhang and Gleason2023). However, cucumber beetle populations often fluctuate widely between years, even in the same location (Saalau Rojas et al., Reference Saalau Rojas, Batzer, Beattie, Fleischer, Shapiro, Williams, Bessin, Bruton, Boucher and Jesse2015). Therefore, the efficacies of the mesotunnel exclusion system for insect pest and bacterial wilt control in muskmelon are also likely to vary annually. Mesotunnels were also an effective barrier to squash bugs and therefore, are also likely to have additional benefits in other cucurbits, given the recent emergence of CYVD (Rodriguez-Herrera et al., Reference Rodriguez-Herrera, Ma, Swingle, Pethybridge, Gonzalez-Giron, Herrmann, Damann and Smart2023) and the persistence of other cucurbit insect pests (e.g., squash vine borer) that may also be yield limiting.
Landscape fabric was an effective barrier for weeds in the inter-bed area in both the mesotunnel and non-covered treatments. However, landscape fabric is more expensive to purchase and install than cover crops and does not provide the soil health benefits of a living mulch (Feldman, Holmes and Blomgren, Reference Feldman, Holmes and Blomgren2000), but can be reused between cropping seasons to reduce the variable costs of production. Cover crop species selection for the inter-bed area is critical for practical success of this system to ensure rapid establishment and competition for weed exclusion, minimize competition with the main crop for resources, and avoid affecting the integrity of the mesotunnel by pushing on the netting. As cover crops, the white clover/ryegrass and ryegrass only were equally effective in achieving biomass cover in the inter-bed area and weed biomass was not different between the treatments suggesting equal weed suppression effects.
The effect of mesotunnels and inter-bed area treatments on yield components varied between years. In 2021, landscape fabric (in a mesotunnel or non-covered) in the inter-bed area resulted in significantly more fruit and marketable fruit than the cover crop treatments, which were not significantly different between each other. Landscape fabric can influence crop production by increasing soil temperature (Monks et al., Reference Monks, Monks, Basden, Selders, Poland and Rayburn1997; Schonbeck and Evanylo, Reference Schonbeck and Evanylo1998). Feldman, Holmes and Blomgren (Reference Feldman, Holmes and Blomgren2000) found that watermelon (Citrullus lanatus) yield was higher when grown on permanent beds covered with landscape fabric compared to compost and bare ground. The improved durability of the landscape fabric also provided benefits by enabling multi-year use compared to single-season polyethylene films but required additional labor for installation. In this study, the beds were formed with black polyethylene films and the treatment was restricted to the inter-bed area primarily for weed management. Higher average maximum air temperatures were observed in the treatment with landscape fabric in the inter-bed area compared to mesotunnels with cover crops in the inter-bed area. In contrast, the weight of non-marketable fruit was also higher in plots with landscape fabric compared to those with cover crops in the inter-bed area. These losses were attributed to a higher incidence of cracked and soft fruit in treatments with landscape fabric in the inter-bed area irrespective of the presence of a mesotunnel. These defects are also often associated with enhanced ripening rates, likely related to higher air temperatures.
Experiment 2
In 2021, bacterial wilt epidemic progress was significantly higher in the on/off/on compared to open ends. However, in 2022, bacterial wilt epidemic progress was higher in the on/off/on and open ends compared to the closed treatment. Cucumber beetle populations followed similar trends with significantly higher populations in the on/off/on than the open ends and closed treatment in both years. These effects are likely to reflect differences in exposure opportunities of the plants to cucumber beetle populations between the treatments. In the on/off/on treatment, the entire net is placed to the side of the mesotunnel before replacement at the end of flowering until first harvest. In the open ends treatment, although the tunnels were open over the same period as the on/off/on treatment, the available area for pest entry was substantially smaller. However, as a trade-off, the on/off/on treatment also provides maximum opportunities for pollinator visitation and hence improvements in yield. Muskmelon plants are andromonoecious and have male staminate and hermaphrodite flowers that produce pollen and nectar (Bomfim et al., Reference Bomfim, Freitas, de Aragão, Walters and Pessarakli2016). They therefore rely exclusively on insect pollination, and hives are often introduced into open fields to enhance pollination (Tschoeke et al., Reference Tschoeke, Oliveira, Dalcin, Silveira-Tschoeke and Santos2015). Muskmelon is also visited by a broad range of pollinators, including wild bee species (Azpiazu et al., Reference Azpiazu, Medina, Adán, Sánchez-Ramos, Del Estal, Fereres and Viñuela2020). During flowering, pollinators, including wild bees and hoverflies, were observed in higher numbers in the on/off/on than in the open ends treatment. Bumblebees were also observed in the on/off/on and open ends treatments, but in significantly lower numbers than in the closed treatment with the commercial hive.
In 2021, flower numbers were not different between the treatments. In 2022, however, there was an increase in flower number in the on/off/on compared to the closed treatments in both weeks. This factor likely led to increased marketable fruit weight and number in both years in the on/off/on compared to the closed treatment. In 2021, the open ends treatment produced more marketable fruit than the closed treatment, but in 2022, marketable fruit number was not significantly different between these treatments. These results suggested that although there was increased bacterial wilt in the on/off/on treatment, the benefits from enhanced pollination resulting in increase in marketable fruit number and weight, that outweighed the adverse effects of the disease. At this location, naturally occurring pollinators were therefore likely present in sufficient populations to increase fruit yield when their access to flowers was maximized by means of removal of the netting over the entire plot in the on/off/on treatment. This finding also suggests that adding a purchased bumblebee hive may not be warranted when opportunities for pollination can be manipulated by net management. However, spatial heterogeneity in pollinator populations across the landscape and the impact of anthropogenic disturbances on pollen limitation for plant reproduction and pollinator abundance and diversity may influence this result (Bennett et al., Reference Bennett, Steets, Burns, Burkle, Vamosi, Wolowski, Arceo-Gomez, Burd, Durka, Ellis, Freitas, Li, Rodger, Stefan, Xia, Knight and Ashman2020).
Conclusion
In experiment 1, mesotunnels provided organic muskmelon production a broad range of benefits, including an effective barrier for cucumber beetles and decreased plant damage from bacterial wilt. Mesotunnels did not affect the incidence and epidemic progress of foliar diseases, powdery mildew, and Alternaria leaf spot. Landscape fabric in the inter-bed area for weed control increased fruit yield in mesotunnels compared to the cover crops of ryegrass/white clover and ryegrass only. However, the ryegrass/white clover and ryegrass only cover crops were equally effective for weed suppression. In experiment 2, the on/off/on pollination treatment led to increased fruit weight and number despite the prolonged exposure times to insect pests. Additional cost–benefit analysis is needed to underpin recommendations for an integrated production system for organic muskmelon.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1742170524000309.
Acknowledgments
This research was supported by the United States Department of Agriculture National Institute of Food and Agriculture (USDA-NIFA) Hatch project NYG-625424, managed by Cornell AgriTech, Cornell University, Geneva, NY; and USDA-NIFA Organic Research and Extension Initiative program, project number 2019-51300-30248. We are grateful for the assistance of Audrey Klein, and Jered Waggoner (listed alphabetically by surname), José González-Acuña (project manager, Iowa State University), the Cornell AgriTech Field Research Unit, and summer field crews of the Pethybridge team for support in trial establishment, evaluation, and harvest.
Competing interests
None.
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