Research Report: Evaluation of Cucumber High Tunnel Trellising Systems

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This research was funded by a Southern SARE Research and Education Grant Specialty Crop.

This material is based upon work supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2021-38640-34724 through the Southern Sustainable Agriculture Research and Education program under subaward number 00002884.  Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s). They should not be construed to represent any official USDA or U.S. Government determination or policy. USDA is an equal opportunity employer and service provider.

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Research Overview

This research evaluated the yield, disease pressure, plant loss, and labor requirements of six cucumber (Cucumis sativus) varieties grown using commonly used high tunnel trellising techniques to assess each method’s economic advantages and disadvantages.

Key Results

• Excelsior, Itachi, and Shintokiwa had the highest proportion of marketable fruit, making them strong candidates for quality-focused production. At the same time, high-yielding cultivars like Socrates, Poniente, and Picolino require improved disease and pest management to reduce blemishes and deformities.
• The Hortonova trellising system produced 19% more marketable fruit and 14% more total yield than the Tomahook (drop-line) system, suggesting it offers a modest advantage for optimizing productivity.
• Cucumbers grown using the Hortonova trellising system achieved a significantly higher net profit than those grown with the drop-line system, driven by slightly lower setup labor costs and increased marketable fruit volume.

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Introduction

Cucumber production in the Southeast faces significant challenges from high disease pressure, primarily due to the region’s hot, humid summer climate. Downy mildew (Pseudoperonospora cubensis) and powdery mildew (caused by fungi in the Podosphaera xanthii) are the most damaging diseases affecting cucurbits, with limited organic management options available (McGrath, 2013). Downy mildew has been identified as the most critical threat to cucurbit production in the region (Holmes et al., 2015).

Organic and sustainable farms often turn to high tunnel production to reduce disease incidence, as the protected environment can decrease pathogen spread and the need for chemical interventions. Within high tunnels, trellising systems further enhance disease management by improving airflow, reducing fruit-to-soil contact, and supporting plant vigor and fruit cleanliness.

Preventative practices are essential in organic systems, where curative treatments are limited. While trellising is widely recognized as a valuable preventative measure, little research has been conducted on the relative effectiveness of different trellising systems in reducing disease and increasing marketable yields under Southeastern conditions.

This study evaluated two trellising methods—Hortinova and drop-line Tomahook—across six cucumber varieties to determine optimal combinations that support grower success through improved plant health and productivity.

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Methods

Research was conducted in 2023 and 2024 in a 30’ x 96’ high tunnel at the Elma C. Research and Education Farm (Lomax) in Concord, North Carolina. Cucumber seedlings were started in a greenhouse on March 7, 2023, and March 9, 2024. Transplanting occurred on April 1, 2023, and April 7, 2024.

Cucumber plants were established in six raised beds measuring 30 inches in width and 90 feet in length. Each bed was covered with black plastic mulch and irrigated using a single drip line. Plants were arranged in two rows per bed with 24-inch in-row spacing. Based on soil test results, soil amendments were applied, including 100 lbs/ac of Nature Safe® 13-0-0 for nitrogen, 60 lbs/ac of Par-4® bone leal 2-14-0 for phosphorus, and 80 lbs/ac of Allganic Potassium Sulfate® 0-0-52 for potassium. 

Two standard trellising systems, a drop-line Tomahook trellis and Hortonova netting, were evaluated. Both trellises hung from a previously installed overhead wire 6-8’ above ground. The wire was attached to the tunnel end walls with eye bolts and 6” turnbuckles with hooks. The Hortonova netting was supported with T posts placed every 15 feet. 

To control diseases, rotating applications of Serenade® and potassium bicarbonate fungicides, Milstop®, and Carb-O-Nator® were used according to the label instructions. Plants were irrigated with a drip irrigation system every 2-3 days for 30 minutes in April, every 1-2 days for 60 minutes in May-July, depending on conditions.

Six cucumber (Cucumis sativus) cultivars were selected to represent various market types, including American pickling, cocktail, European slicing, and Asian slicing cucumbers. The objective was to evaluate whether specific cucumber types differed in yield and disease susceptibility, particularly to downy mildew (Pseudoperonospora cubensis) and powdery mildew (Podosphaera xanthii), under different pruning and trellising regimes. The varieties selected and their key characteristics are as follows:

A randomized split-plot design was employed with two trellising treatments—drop-line (Tomahook) and vertical netting (Hortonova)—and six cucumber (Cucumis sativus) cultivar sub-treatments: ‘Poniente’, ‘Socrates’, ‘Excelsior’, ‘Picolino’, ‘Shintokiwa’, and ‘Itachi’. Each treatment combination was replicated three times.

Ripe fruit was harvested weekly, sorted as marketable, unmarketable (diseased, cracked, or poorly shaped fruit), and then counted and weighed.  Disease severity was scored monthly using a 10-point scale, where a score of 1 indicated approximately 10% of plants within a treatment were affected by disease, and a score of 10 indicated approximately 100% disease incidence. Yield and disease data were analyzed in R version 4.4.2 (R Core Team, 2025). Marketable and unmarketable fruit were analyzed separately; differences among treatments were tested using Linear Mixed Effects Model ANOVA (package lme4), with block and year as random effects and trellis and variety as fixed effects, and means were separated using Estimated Marginal Means (package emmeans).  

Results

Powdery Mildew was present from mid-April onwards, but was secondary in its effects. It was present on lower, moist leaves early in the season; however, the hotter and later in the season kept it at bay. Downy Mildew was never detected in the tunnel during these two seasons. Black Rot and Gummy Blight were devastating in year 1.  Disease scores were lowest for Shintokiwa; highest for Itachi, Picolino & Poniente; the others had intermediate scores (Figure 1). There was no significant difference in disease score by trellis type (Figure 2). 

Figure 1. Disease scores by variety

Figure 2. Disease Scores by trellis type

Excelsior and Itachi produced a significantly higher proportion of marketable fruit relative to unmarketable fruit, followed by Shintokiwa. In contrast, Socrates, Poniente, and Picolino had lower marketable-to-unmarketable ratios (Figure 3), despite being among the highest overall yielders (Figure 4). These results suggest that Socrates, Poniente, and Picolino may be more susceptible to fruit blemishes and deformities. However, with improved pest and disease management, as well as enhanced sanitation practices, these cultivars have strong potential for high-quality yield. Varieties grown using the Hortonova trellising systems had significantly more marketable fruit overall than varieties grown using the Tomahook method (Figure 5).

Figure 3. Marketable fruit as a percentage of total fruit harvested

Figure 4. Total marketable and unmarketable fruit by variety

Figure 5. Total marketable and unmarketable fruit by trellising system

Cucumbers grown using the Hortonova trellising system yielded a 32% higher net profit than those grown with the drop-line system (Table 1) due to slightly lower setup labor costs and a higher volume of marketable fruit.

Table 1. Estimated Economic Analysis for Two Types of Trelissing Systems, drop-line and Hortonova, in a 30’ by 96’ High Tunnel.

Conclusion

Over the two growing seasons, disease pressure varied by pathogen, cultivar, and trellising system. While powdery mildew was present early in the season, it remained secondary due to rising temperatures, and downy mildew was never detected. Black rot and gummy blight were the most damaging diseases, particularly in the first year. Shintokiwa showed the lowest disease score among the cultivars, while Itachi, Picolino, and Poniente had the highest. Trellis type did not significantly affect disease score.

Excelsior and Itachi consistently produced the highest proportion of marketable fruit, followed by Shintokiwa. Although Poniente, Socrates, and Picolino had high total yields, they also had a lower marketable to unmarketable fruit ratio, likely due to greater susceptibility to blemishes and deformities. These findings indicate that these high-yielding cultivars could produce better marketable outcomes with improved pest and disease management and enhanced sanitation.

Though unmarketable fruit percentages were similar, the Hortonova trellis system performed slightly better than the Tomahook method in total and marketable yield. Pickling types were the least productive in total yield due to their smaller fruit size. Cultivar selection and trellising methods influence productivity, with disease management and postharvest quality playing key roles in marketable yield outcomes.

Cucumbers grown using the Hortonova trellising system achieved a significantly higher net profit than those grown with the drop-line system, driven by slightly lower setup labor costs and increased marketable fruit volume.

Literature Cited

Holmes, G. J., Ojiambo, P. S., Hausbeck, M. K., Quesada-Ocampo, L., Keinath, A.P. (2015). Resurgence of cucurbit downy mildew in the United States: A watershed event for research and extension. Plant Disease, 99 (4), 428-441.

McGrath, M. T. (2013). Mildew Control in Organic Cucurbits. American Vegetable Grower, 61(6), 21–22.