Horticulture Series # 224

Jonathan R. Schultheis & Keith D. Starke, Department of Horticultural Science

General Cultural Practices

The squash study was established on black plastic mulch. Pesticides used on all plots were chemicals labelled for that crop, 2018 North Carolina Agricultural Chemicals Manual.

Acknowledgements

View the pdf version of the 2018 squash evaluations

We gratefully acknowledge the assistance of Cathy Herring, (Superintendent), and Charles Barrow, (Horticulture Supervisor, Central Crops Research Station, Clayton, NC), as well as, the personnel at the research station for their help in establishing, maintaining, and harvesting the squash cultivar evaluation trial. We want to acknowledge the following summer employees for their assistance with the trials: Chandler Fulmer, Benjamin Indermaur, Tanner Seay, Shannon Dexter, Elizabeth Indermaur, as well as, graduate student; Fernando Montero De Espinosa. We would also like to thank Joy Smith for conducting the statistical analysis on the data that was collected in this trial. The cooperation and support of Clifton, Bejo, Enza Zaden, HM Clause, Seedway, Seminis/Monsanto, and Syngenta are also appreciated. View the pdf version of the 2018 squash evaluations.

Disclaimer

This publication presents data from the cultivar evaluation trial conducted during 2018. Information in this report is believed to be reliable but should not be relied upon as a sole source of information. Limited accompanying detail is included but excludes some pertinent information, which may aid interpretation.

Zucchini Squash Cultural Practices for 2018 Cultigen Study, Central Crops Research Station; Clayton, NC

Introduction

In 2018, summer squash production totaled 2,400 acres in North Carolina. Summer squash remains an important crop to North Carolina producers as the state ranked 7th among those states that produced the crop nationwide in 2013. Summer squash ranks among the top 10 vegetables grown in North Carolina. Squash represents significant economic importance to North Carolina growers with a crop value of $10.1 million in 2017. North Carolina growers have maintained their competitiveness through producing squash varieties that are highly desired by the consumer. In an effort to remain competitive in the marketplace and maximize profitability growers seek to grow squash varieties that will provide them with the highest yields and greatest overall fruit quality. The zucchini market in North Carolina has typically been supplied with a medium green fruit, however, some markets have seen increased demand for cultivars that produce a darker green fruit. Summer squash plantings in North Carolina typically experience higher incidence of disease and insect pressure as they are harvested in the fall when environmental factors favor increased presence of these plant pests. In 2018 the field trial was planted on 4 May and we began harvesting on 4 June. The squash were rated for marketable and nonmarketable yields, for early and late production, and for consistency of production throughout the harvest period. Quality measurements were collected and average plant stand counts were calculated to conduct the most complete evaluation of each cultivar in the field trial. We again included the number of fruit produced per plant over various harvest intervals, and for the entire production season to compliment the yield data.

Materials and Methods

Seeds were sown on 4 May 2018. Hills with seed skips were replanted 5 days after planting to maximize plant stand counts in each plot. Final stand counts were taken on 25 May (approx. 3 weeks after initial planting). The study area was treated with Telone C-17 (10 gal/ac) on 1 November 2017. A broadcast equivalent application of 12-6-24 pre-plant fertilizer (400 lb/ac) was made across the entire trial area on 23 April 2018. Black plastic mulch (0.70 mil thick high density film, 48 inches wide; B.B. Hobbs, Clinton, NC ) and drip irrigation tape (NETAFIM, 12 inch spacing, 0.24 gal/hr; NETAFIM, Tel Aviv, Israel) with these materials being laid out in the field on 23 April 2018. The herbicides Prefar (5 qts/ac), Sonolan (4 pts/ac) and Honcho (2 qts/ac) were applied to row middles on 4 May 2018. The insecticides Asana, Assail, FanFare, Endosulfan, were rotated and applied as a preventative measure beginning 15 May and on the following dates: 23 and 31 May; 6, 13, 20 and 27 June 2018. The following fungicide products were used as a preventive measure and on a rotational basis throughout the entire growing season: Presidio, Pristine, Procure, Proline 480, Ranman, and Zampro. The first fungicide application was made on 31 May; and on the following dates 6, 13, 20 and 27 June 2018. Liquid fertilizer (7-0-7) was applied through drip irrigation beginning 10 May and on the following dates: 16, 23 and 30 May; 6, 13, 20, 27 and 29 June. Harvests were conducted three times per week for the trial with a total of 13 harvests. The first harvest was 4 June and the final harvest (#13) was completed on 2 July 2018.

Most fruit were harvested when the blossom was detached from the fruit, and then categorized as marketable or nonmarketable. Fruit that were small or undersized, or were misshapen, were categorized as culls (non-marketable). Graded fruit were weighed and counted for each category and plot. The study design was a randomized complete block with four replications. Other than yield, other quality measurements taken were: percent plant stand and average fruit length and width. Overall, plant stands were excellent at 100%. Disease and insect pressure were very minimal, therefore, overall fruit yield and quality were very good for the entire study. The highest yielding (> 700 boxes/acre) cultigens (advanced line or cultivar) for marketable fruit in early harvests (1-4) were Ladoga and SV9494YG, while the lowest yielding (< 500 boxes/acre) were Sanabria, Spineless King, SV0914YG and SV9043YG (Table 1). Mid-season included 5 harvests (5-9). Yields were higher for all cultigens in the mid-season versus the early or late season harvests (10-13). The highest yielding mid-season cultigens (> 800 boxes/acre) were Cash Machine, Ladoga and SV9494YG, while yields were again highest for the late harvests for these same three cultigens. The highest cull fruit production was in the late harvests for all cultigens except Leopard. The cultigens that produced the most culls were Zucchini Elite and SVYG6633. No virus symptoms were observed in any fruit.

Marketable yields across all harvests (13) were greatest (> 2000 boxes/acre) for Cash Machine, Ladoga and SV94949YG while Bejo 3251, Sanabria and Zucchini Elite had the lowest marketable yields (<1500 boxes/acre) (Table 2). Cull fruit production was highest for Zucchini Elite (479 boxes/acre, 24% of fruit produced) followed by SVYG6633 (364 boxes/acre, 18% of fruit produced). Disease pressure was minimal throughout the season in this study, however, insect pressure was managed well through the early and mid-season harvests but increased pest presence in the late harvests (10-13) may have impacted fruit quality. Marketable fruit was 88% across all entries for the season (Table 2). Entries that performed well above the average were SVYG5395 (95%), Leopard (94%), SV0914YG ((93%), SV6009 and SV9494YG (92%), Ladoga (91%). The entry with the highest cumulative yield (13 harvests) of marketable fruit was SV9494YG (2192 boxes/acre) and Bejo 3251 (1485 boxes/acre) was the lowest.

The highest percentage of marketable squash, averaged across entries, was obtained in the mid-season harvests (5-9) (95%) followed by early season harvests (1-4) (90%) and late season harvests (9-12) (75 %) (Table 3). The percentage yield of marketable fruit was especially high for SV0914 (97%), Ladoga (96%), SV6009YG and SVYG5395 were (95%) for early season harvests (1-4); Leopard, Sanabria and SVYG5395 were (99%); Bejo 3251 and SV6009YG were (97%) for mid-season harvests (5-9); and for late season harvests (10-13) SVYG5395 (89%) and Leopard yielded (88%) marketable fruit.

The average number of fruit per plant for each entry during three harvest intervals are shown in Table 4. Cumulative marketable fruit weight per plant over all harvests (13) averaged 88% (Table 5), while cumulative marketable fruit number per plant averaged 83% (Table 6).

The cumulative number of fruits per acre for each cultigen across all harvests (13) and for each grade are provided in (Table 7). The number of fruits per acre for each cultigen for early season harvests (1-4), mid-season harvests (5-9) and late season harvests (10-13) are provided in Table 8, with corresponding percentages in Table 9.

Plant stands were excellent (100%) for all cultigens and average fruit length and widths were determined (Table 10). In this trial Cash Machine, Spineless King, Zucchini Elite and SV9494YG produced longer fruits. In addition, all plots in the study were rated for the following characteristics, plant canopy, foliage color, presence or absence of spines and overall vigor (Table 11). Cultigens with a dense canopy included Ladoga, Sanabria and Spineless King, while cultigens with the least dense canopies were Bejo 3251, SV6009YG and SVYG5395. Cultigens with few or no spines were Spineless King and SVYG6633. The most vigorous vine growth was recorded on Spineless King, while cultigens with the least vigorous vines were SVYG5395 and Cash Machine.

Summary

Overall, yields and fruit quality in this study were excellent. Excellent growing conditions with minimal pest pressure were important factors that contributed to these results.

Zucchini Squash Cultigen and Seed Company

• Cash Machine – Enza Zaden
• Green Machine – Enza Zaden
• Ladoga – Bejo
• Leopard – HM Clause
• Payload – Syngenta
• Sanabria – Bejo
• Spineless King – Seedway
• Zucchini Elite – Clifton Seed
• Bejo 3251 – Bejo
• SV6009YG – Seminis
• SV0914YG – Seminis
• SV9043YG – Seminis
• SV9494YG – Seminis
• SVYG5395 – Seminis
• SVYG6633 – Seminis

View Images of 15 Zucchini cultigens on page 7 of the pdf booklet

Table 1. Zucchini Squash cultigen study yields¹, number of 20 lb boxes per acre, per indicated harvests for replicated treatments. Clayton, NC, 2018.

Number of 20 pound boxes per acre

¹ Total of 13 harvests. Planting was 4 May 2018. Harvests 1-4 occurred on 4, 6, 8 and 11 June; Harvests 5-9 occurred on 13, 15, 18, 20 and 22 June; Harvests 10-13 occurred on 25, 27, 29 June and 2  July 2018.
² Culls consisted primarily of misshaped fruit.

Number of 20 pound boxes per acre

³ Fruit were discolored or rough/disfigured due to virus.

Table 2. Zucchini Squash cultigen study yields, cumulative boxes, (20 lbs.), per acre, among all harvests1. Clayton, NC, 2018.

¹ Total of 13 harvests. Planting was 4 May 2018. Harvests 1-4 occurred on 4, 6, 8 and 11 June; Harvests 5-9 occurred on 13, 15, 18, 20 and 22 June; Harvests 10-13 occurred on 25, 27, 29 June and 2 July 2018.
² Culls consisted primarily of misshaped fruit.
³  Fruit were discolored or rough/disfigured due to virus.

Table 3. Zucchini Squash cultigen study yields¹. Percentage marketable, cull, and virus symptomatic fruit per indicated harvests by number of 20 lb boxes for replicated treatments. Clayton, NC, 2018.

Percentage (%) of yield based upon grade.

¹ Total of 13 harvests. Planting was 4 May 2018. Harvests 1-4 occurred on 4, 6, 8 and 11 June; Harvests 5-9 occurred on 13, 15, 18, 20 and 22 June;  Harvests 10-13 occurred on 25, 27, 29 June and 2 July 2018.
² Culls consisted primarily of misshaped fruit.
³ Fruit were discolored or rough/disfigured due to virus.

Table 4. Zucchini Squash cultigen study yields1, average number of fruit per plant, per indicated harvests for replicated treatments. Clayton, NC, 2018.

Number of fruit per plant per harvest period²

Number of fruit per plant per harvest period²

¹ Total of 13 harvests. Planting was 4 May 2018. Harvests 1-4 occurred on 4, 6, 8 and 11 June; Harvests 5-9 occurred on 13, 15, 18, 20 and 22 June; Harvests 10-13 occurred on 25, 27, 29 June and 2 July 2018.
² Average number of fruit harvested from each plant at each harvest period (i.e.: 1-5; 6-10; 11-15).
³ Culls consisted primarily of misshaped fruit.
⁴ Fruit were discolored or rough/disfigured due to virus.

Table 5 . Zucchini squash cultigen study. Cumulative fruit weight and percent per plant among all harvests¹. Clayton, NC, 2018.

¹ Total of 13 harvests.
² Culls consisted primarily of mishaped fruit.
³ Fruit were discolored or rough/disfigured due to virus.

Table 6. Zucchini squash cultigen study yields, cumulative fruit number per plant and percent per grade among all harvests¹. Clayton, NC, 2018.

¹Total of 13 harvests.
² Culls consisted of primarily misshaped fruit.
³ Fruit were discolored or rough/disfigured due to virus.

Table 7. Zucchini squash cultigen study. Cumulative fruit number per acre and percentages, among all harvests¹. Clayton, NC, 2018.

¹ Total of 13 harvests.
² Culls consisted of primarily misshaped fruit.
³ Fruit were discolored or rough/disfigured due to virus.

Table 8. Zucchini squash cultigen study yields1. Number of fruit per acre by grade per indicated harvests for replicated treatments. Clayton, NC, 2018.

Number of fruit per acre per harvest period

¹ Total of 13 harvests. Planting was 4 May 2018. Harvests 1-4 occurred on 4, 6, 8 and 11 June; Harvests 5-9 occurred on 13, 15, 18, 20 and 22 June; Harvests 10-13 occurred on 25,   27, 29 June and 2  July 2018.
² Culls consisted of primarily misshaped fruit.
³ Fruit were discolored or rough/disfigured due to virus.

Table 9. Zucchini squash cultigen study¹. Percent fruit number per acre per indicated harvests for replicated treatments. Clayton, NC, 2018.

¹ Total of 13 harvests. Planting was 4 May 2018. Harvests 1-4 occurred on 4, 6, 8 and 11 June; Harvests 5-9 occurred on 13, 15, 18, 20 and 22 June;   Harvests 10-13 occurred on 25, 27, 29 and 2 July 2018.
² Culls consisted of primarily misshaped fruit.
³ Fruit were discolored or rough/disfigured due to virus.

Table 10. Zucchini Squash cultigen study – Percent plant stand count and average fruit length and width among replicated treatments. Clayton, NC, 2018.

Fruit Size (cm)

¹ Final plant stand count was taken on 25 June 2018.

Table 11. Zucchini Squash cultigen study – Plant growth quality data. Clayton, NC, 2018.

¹ Canopy ratings are on a scale of 1-10; 1 = open, 10 = dense.
² Color ratings are for plant foliage on a scale of 1-10; 1 =  pale green , 10 = dark green.
³ Color ratings are for plant foliage on a scale of 1-10; 1 = no spines, 10 = coarse spines.
⁴ Color ratings are for plant foliage on a scale of 1-10; 1 = smaller plants, 10 = robust plants.