Hort. Series # 239

Principle Investigators:
Jonathan R. Schultheis, Professor and Extension Specialist, Department of Horticultural Science, NC State University; Keith D. Starke, Research Operations Manager, Central Crops Research Station, Clayton, NC; Stuart W. Michel, Research Technician, Department of Horticultural Science, NC State University

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Acknowledgments

We gratefully acknowledge the assistance of Charles Barrow (Horticulture Crops Supervisor), Central Crops Research Station, Clayton, NC, as well as the personnel at the research station for their help to establish, maintain, and harvest the cultigen evaluation trials. We want to also acknowledge the following summer research assistants for their help with the study: Benjamin Indermaur, Tanner Seay, Grayson Parrish, Samantha Mowery, and Cady Bailey. The cooperation and support of the following seed companies and university is also greatly appreciated: BASF/Nunhems, Seminis, Syngenta Seeds, Inc., Texas A&M University, and VoloAgri / US Agriseeds.

General Cultural Practices

This melon study was grown using recommended practices for commercial melon production in North Carolina. All plots in the study used black plastic mulch and were fertigated with drip irrigation. Furthermore, pesticides used on all plots were chemicals labeled for use on that crop, (2021 North Carolina Agricultural Chemicals Manual).

Disclaimer

This publication presents data from the orange flesh and specialty melon cultigen evaluation studies conducted during 2021. 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. 

Orange Flesh and Specialty Melon Cultural Practices for 2021 Cultigen Study, Central Crops Research Station, Clayton, NC

Introduction

There has not been a dramatic change in acreage for orange flesh and specialty melon production in North Carolina and data has not been published in recent years, however, it is estimated that 3,000 to 4,000 acres are produced in the state. In 2017 a survey of US growers estimated orange flesh melon production was 58,000 acres (USDA, National Agriculture Statistics Service). Since 2013, the US orange flesh melon crop has seen significant decreases in acreage. In 2013 there were 74,000 acres valued at 319 million whereas in 2017 US acreage was reported to be 58,000 with a total crop value of $267 million. Further reporting showed domestic orange flesh melon prices have steadily declined from their peak of 0.25/lb in 1980 to a season-average of 0.15/lb in 2018 (USDA, National Agriculture Statistics Service). The majority of melons grown in North Carolina are an eastern shipping type with ‘Athena’ being the principal cultivar produced for more than two decades. In addition to the eastern shipper type orange flesh melon, other orange flesh melons being grown on much smaller acreage include Extended Shelf Life (ESL), Long Shelf Life (LSL) melons, often termed Harper melons, and a third type termed Italian (Tuscan) melons. The ESL or LSL melons, as the name suggests, will hold for a longer period than the eastern type melons. Flesh firmness and sweetness tend to be higher in the ESL or LSL type melons than in eastern type melons. Greater flesh firmness allows the fruit to have a better shelf life after harvest. This trait increases the “shipability”, a term often referred to as giving the fruit “better legs”. It can be more difficult to determine readiness on LSL melons and this has delayed willingness from some growers, especially in North Carolina, to move into larger scale production of these melons. In 2021, several new cultigens were evaluated in our melon field study that included 26 advanced lines (cultigens) or cultivar entries from 4 seed companies and 1 University. All entries were evaluated for yields, earliness, and various other qualities.

Materials and Methods

Sowing and Transplant Production

Once all seeds were received from participating companies, they were planted into 72 cell Poly trays to grow transplants (Hummert Int.; Earth City, MO). Seeds of orange flesh and specialty melons were sown on 30 March 2021. The trays of sown seeds were placed in a germination room for about one day. Temperature in the germination room averaged about 85℉ and moisture was elevated to around 70%. The planting medium used was a “Fine Germinating Mix”, a commercial soilless mix (SunGro, Agawam, MA). Approximately 3 weeks after seeding, transplants were placed in a “hardening” greenhouse for approximately one week before being transplanted in the field.

Field Preparations 

On 28 November 2020, the field study area (0.28 acres) was fumigated with Telone II at 10 gal/ac. A complete fertilizer (12-6-24) (400 lb/ac) was applied broadcast and black polyethylene plastic mulch (0.70 mil thick high density plastic film, 48 inches wide; B.B. TriEst Ag Group Inc., Clinton, NC) was laid in the field on 14 April 2021. Drip tape (NETAFIM, 12 inch spacing, 0.24 gph; NETAFIM, Tel Aviv, Israel) was installed beneath the plastic mulch and was utilized to fertigate the crop throughout the growing season.

Planting

Orange flesh and specialty melon plants were established in the field on 23 April 2021. Plot size was one row with 10 plants per plot (20 ft) with in-row spacing of 2 feet and between-row spacing of 5 feet. Field arrangement for the orange flesh melon cultigen study was a Randomized Complete Block Design (RCBD) with four replications. Plots that were missing plants were replanted approximately 7 days after transplanting to achieve 100% stand, in most cases. 

Fertilizer and Pest Management 

A total of 48 lb/ac N, 24 lb/ac P, and 96 lb/ac K were applied broadcast (pre-plant) to the entire study area. Liquid fertilizer with a 7-0-7 analysis was initially applied through drip fertigation on 5 May 2021 and subsequently on the following dates: 12, 19, and 26 May 2021; 2, 9, 15, 21, and 30 June 2021; 7 and 14 July 2021. A total 115 lb/ac of N and 115 lb/ac of K were applied via fertigation throughout the growing season.

Herbicide Strategy (3 pts/ac) was applied to row middles for pre-emergent weed control on 26 April 2021. Gramoxone (3 pts/ac) was applied to row middles on 13 May 2021.

Fungicides were initially applied on 2 June 2021 and subsequently on the following dates: 9, 16, 23 and 29 June 2021; 7, 14, and 21 July 2021. The following fungicides were rotated to avoid potential development of resistance from disease: Procure (6 oz/ac), Ranman (2.75 oz/ac), Previcur Flex (1.2 pts/ac), Vivando (15.4 oz/ac), and Orondis Opti (2 pts/ac).

Insecticides were applied as needed throughout the growing season beginning 26 May 2021 and subsequently on the following dates: 2, 9, 16, 23, and 29 June 2021; 7, 14, and 21 July 2021. The following insecticide products were alternated throughout the season to avoid potential resistance development in insect species: Assail (4 oz/ac) (5.5 oz/ac) (5.4 oz/ac), FanFare (5 oz/ac), Perm-up (6 oz/ac) (4 oz/ac), and Bifenture EC (4 oz/ac). Miticide Agrimite (.75 lb/ac) was applied on 29 June 2021.

Harvest and Yield Data Collection

There were 15 total harvests of the orange flesh and specialty melon cultigens. The first harvest was 28 June 2021, followed by: 30 June 2021; 2, 6, 7, 9, 10-12, 13-14, 16, 19, 22, 23, 26, 28, and 30 July 2021. Some harvests have date ranges and were done over multiple days and counted as one harvest time to be consistent with yield and quality data collection and evaluations. Daily harvests in some cases were done to optimize fruit quality for shipment to Texas and Arizona to evaluate internal fruit quality and microbes, respectively.

Quality Evaluations

Evaluations of each melon entry included: yield, fruit size, production earliness, soluble solids, fruit shape and size, and interior flesh firmness. Soluble solids were measured by cutting a piece of fruit from the center and squeezing out the fruit juice onto a digital refractometer (Atago, Vernon Hills, IL). Flesh firmness was measured (recorded in pounds) by using a Penetrometer FT 011 with a 7/16” plunger tip, (QA Supplies LLC, Norfolk, VA). Melon samples were obtained by cutting through the ground spot of the fruit, lengthwise, from the fruit’s stem end to blossom end. Flesh firmness measurements were taken in four areas of the fruit: top side, ground spot side, stem end, and blossom end. The reported measures on flesh firmness are an average of three fruit per plot or 12 fruit per cultigen. The majority of quality measurements were taken when the melons became ripe between the first and fourth harvests for a given cultigen, with some exceptions.

Results

A representative photograph was taken of each cultigen which aimed to illustrate key characteristics that provided the best representation when harvested at the appropriate harvest stage (Fig.1).

Yield and Size

The highest yielding orange flesh and specialty melon cultigens for marketable fruit weight for the early-season harvests (1-5) were Athena (250 cwt/ac), Flavor Time (232 cwt/ac), and VM18011260(LSL) (182 cwt/ac) (Table 1). The average marketable yield for the early-season harvests (1-5) was 65 cwt/ac. The orange flesh and specialty melon cultigens with the highest average fruit weight for the early-season harvests (1-5) were Flavor Time (6.0 lb/fruit), Charlotte (HD) (5.4 lb/fruit), Heidi (5.2 lb/fruit), and VM18011260(LSL) (5.1 lb/fruit). The average fruit weight for the early-season harvests (1-5) was 3.7 lb/fruit.

The highest yielding orange flesh and specialty melon cultigens for marketable fruit weight for the mid-season harvests (6-10) were TH-5 (408 cwt/ac), TH-17 (390 cwt/ac), TH-6 (364 cwt/ac), and TH-12 (359 cwt/ac) (Table 2). The average marketable yield for the mid-season harvests (6-10) was 249 cwt/ac. The orange flesh and specialty melon cultigens with the highest average fruit weight for the mid-season harvests (6-10) were Charlotte (HD) (8.0 lb/fruit), Flavor Time (6.6 lb/fruit), and 252 HQ (HD) (6.4 lb/fruit). The average fruit weight for the mid-season harvests (6-10) was 4.6 lb/fruit. All TH lines were at or below the average fruit weight.

The highest yielding orange flesh and specialty melon cultigens for marketable fruit weight for the late-season harvests (11-15) were Charlotte (HD) (231 cwt/ac), 252 HQ (HD) (199 cwt/ac), and VM18011260(LSL) (140 cwt/ac) (Table 3). The average marketable yield for the late-season harvests (11-15) was 73 cwt/ac. The orange flesh and specialty melon cultigens with the highest average fruit weight for the late-season harvests (11-15) were Heidi (6.5 lb/fruit), Charlotte (HD) (6.1 lb/fruit), TH-20 (5.8 lb/fruit), and 252 HQ (HD) (5.8 lb/fruit). The average fruit weight for the late season harvests (11-15) was 4.2 lb/fruit.

The top five highest yielding orange flesh and specialty melon cultigens for marketable fruit weight for the cumulative harvests (1-15) were VM18011260(LSL) (576 cwt/ac), Flavor Time (528 cwt/ac), TH-5 (481 cwt/ac), Charlotte (456 cwt/ac), and TH-17 (446 cwt/ac) (Table 4). The lowest yielding orange flesh and specialty melon cultigen for marketable fruit for the cumulative harvests (1-15) was TH-10 (125 cwt/ac). This is because most fruits were less than 3 lb, which was considered the minimal size threshold for a marketable fruit. The average marketable yield for the cumulative harvests (1-15) was 376 cwt/ac. At significance level 0.05, the LSD for marketable yield was 111. The orange flesh and specialty melon cultigens with highest average fruit weight for the cumulative harvests (1-15) were Charlotte (HD) (6.8 lb/fruit), Flavor Time (6.1 lb/fruit), 252 HQ (HD) (6.1 lb/fruit), and Heidi (6.0 lb/ac). The average fruit weight for the cumulative harvests (1-15) was 4.3 lb/fruit.

The orange flesh and specialty melon cultigens with the highest number of marketable fruit per acre for the early-season harvests (1-5) were Athena (5808 fruit/ac), Tanager (3872 fruit/ac), and Flavor Time) (3630 fruit/ac) (Table 5). The average marketable fruit number for the early-season harvests (1-5) was 1419 fruit/ac.

The orange flesh and specialty melon cultigens with the highest number of marketable fruit per acre for the mid-season harvests (6-10) were TH-17 (9922 fruit/ac), TH-5 (9317 fruit/ac), TH-12 (9317 fruit/ac), and TT-DV (Da Vinci) (7502 fruit/ac) (Table 6). The average marketable fruit number for the mid-season harvests (6-10) was 5510 fruit/ac.

The orange flesh and specialty melon cultigens with the highest number of marketable fruit per acre for the late-season harvests (11-15) were Charlotte (HD) (3630 fruit/ac), 252 HQ (HD) (3388 fruit/ac), and VM18011260(LSL) (2783 fruit/ac) (Table 7). The average marketable fruit number for the late-season harvests (11-15) was 1489 fruit/ac.

The orange flesh and specialty melon cultigens with the highest number of marketable fruit per acre for the cumulative harvests (1-15) were TH-17 (11374 fruit/ac), VM18011260(LSL) (11011 fruit/ac), and TH-5 (10890 fruit/ac) (Table 8). The orange flesh and specialty melon cultigen with the lowest number of marketable fruit per acre for the cumulative harvests (1-15) was TH-10 (3388 fruit/ac). The average marketable fruit number for the cumulative harvests (1-15) was 8200 fruit/ac. At significance level 0.05, the LSD for marketable fruit number per acre was 2399.

Percent fruit weight per indicated size category are provided for early-season harvests (1-5), mid-season harvests (6-10), late-season harvests (11-15), and cumulative harvests (1-15), respectively (Tables 9, 10, 11, 12).

An average of 66% of orange flesh and specialty melon fruit weight was harvested in the mid-season harvest (6-10) (Table 13). 15% and 20% of orange flesh and specialty melon fruit weight was harvested in the early-season harvests (1-5) and late-season harvests (11-15), respectively.

Percent fruit number per indicated size category are provided for early-season harvests (1-5), mid-season harvests (6-10), late-season harvests (11-15), and cumulative harvests (1-15), respectively (Tables 14, 15, 16, 17).

An average of 64% of orange flesh and specialty melon fruit number was harvested in the mid-season harvests (6-10) (Table 18). 16% and 20% of orange flesh and specialty melon fruit number was harvested in the early-season harvests (1-5) and late-season harvests (11-15), respectively.

Quality

Interior fruit quality measurements for orange flesh and specialty melon included: soluble solids, length and diameter, and flesh firmness. The orange flesh and specialty melon cultigens with the highest Brix rating were Flavor Time (14.5), Heidi (14.5), and SV942ML (14.1) (Table 19). The orange flesh melon across cultigens with the lowest Brix reading was F-39 (10.0). The average Brix reading was 12.3. The length and diameter ratio was consistent across all orange flesh and specialty melon cultigens with an average length and diameter ratio of 1.0. At significance level 0.05, the LSD for average length and diameter was 0.1. The orange flesh and specialty melon cultigens with the highest flesh firmness rating were SV942ML (6.7), Heidi (6.4), and Mokaya (6.1). The orange flesh and specialty melon cultigen with the lowest flesh firmness rating was TH-6 (2.4). The average flesh firmness rating was 4.1.

Summary

The field and growing conditions throughout the harvest period were relatively wet for eastern North Carolina; a total of 13.7 inches of precipitation in June and July of 2021 at the Central Crops Research Station in Clayton, NC. Seventeen entries included in the study were submitted from Texas A&M. Those cultigens were F-39, HD-150, HT-IG, TH-1, TH-5, TH-6, TH-9, TH-10, TH-12, TH-13, TH-16, TH-17, TH-18, TH-19, TH-20, TT-DV, and 252 HQ (HD). Fruits from these cultigens were shipped to Texas and Arizona to be evaluated for internal chemistry, and as part of a food safety and soil-borne pathogen evaluation study, respectively. These results will be published in another periodical or journal. Charlotte (HD), HD-150, and 252 HQ (HD) are honeydew melons. VM18011249 (LSL) and VM18011260 (LSL) are long shelf life melons.

Financial Support

In addition to the seed companies, this program has been supported by the College of Agriculture & Life Sciences, the North Carolina Agriculture Research Service, and the North Carolina Cooperative Extension Service. We want to acknowledge support for this study was provided by the National Center of Excellence for Melon at the Vegetable and Fruit Improvement Center of Texas A&M University through the following grant project: USDA-NIFA-SCRI-2017-51181-26834 (Mission Melons | National Center of Excellence). We also want to acknowledge support for this study was provided by the U.S. Department of Agriculture, National Institute of Food and Agriculture, for the CucCAP Specialty Crop Research Initiative grant under award number 2020-51181-32139