Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Each year the University of Delaware conducts seedless watermelon variety trials which helps to inform the industry on the performance of current and newly developed varieties under Delmarva growing conditions and helps growers choose the best varieties to match growing and marketing needs.
Growers should select varieties based on market needs, marketability, and productivity. This includes yield, maturity, longevity, size distribution, appearance (rind color, shape), flesh quality (color, sugars), flesh density, limited defects such as hollow heart susceptibility, plant vigor, and disease resistance (Fusarium, anthracnose), and field holding ability. Pollenizers should be matched to the seedless variety to provide early and extended pollen production, disease resistance, and appropriate vigor (too vigorous will compete with the seedless).
The 2017 Seedless Watermelon Variety Trial included 33 varieties from 9 participating companies. The purpose of this trial was to evaluate seedless watermelon varieties for yield, quality and maturity. The trial was conducted at the Thurman Adams Research Farm, University of Delaware, Carvel Research Center.
Plants were transplanted to the field on May 17, 2017. Due to the late spring, plots were not harvested until August. Fruit were harvested three times. The first harvest was on August 2 and 3 at 77 days after transplanting (DAT), the second harvest was 95 DAT, and the final harvest was in early September at 115 DAT. The weight of each watermelon harvested was recorded individually. Five marketable watermelons from each plot were cut and evaluated for presence of hollow heart and soluble solids levels.
The highest yielding varieties in the trial in terms of marketable pounds per acre were: Crunchy Red, 9651, Turnpike, 9601, Bottle Rocket, Warrior, SV 0241 WA, Fascination, Red Amber, ORS 6278, Kingman and XWT 6009. This high yielding group ranged from 135,220 to 99,230 lbs per acre.
The highest yielding varieties in the trial in terms of fruit per acres were: Crunchy Red, Turnpike, SV 0241 WA, Warrior, Kingman, ORS 6151, and 9601 ranging from 7,836 to 6396 melons per acre.
All varieties produced more than 40% of their yield on the first harvest. The following varieties produced more than 60% of their yield on the first harvest: ORS 6253, SV 3105 WA, ORS 6278, Red Amber, WDL 2413, ORS 6260, Charismatic, ORS 6305, Road Trip Captivation, XWT 6008, ORS 6151, Fascination, Bottle Rocket, Summer Breeze, and 7197. Those varieties with extended harvest (50% or more harvested in the second and third harvest) were Secretariat, Turnpike, and 9601.
Varieties were also sorted according to average fruit in each of four weight classes: 60-count (9.0-13.5 lbs), 45 count (13.6-17.5 lbs), 36 count (17.6-21.4 lbs) and 30 count (>21.5 lbs). In general, fruit weights were above average in 2017. Large fruited varieties with average weights over 18 pounds were Bottle Rocket, Maxima, SV 3105 WA, ORS 6278, ORS 6305, Joy Ride, and Road Trip. Medium fruited varieties over 16 pounds included Red Amber, Captivation, Summer Breeze, WDL 2413, Crunchy Red, 7187, ORS 6260, 9601, XWT 6009, 7197, Fascination, Wolverine, Unbridled, Turnpike, Warrior, XWT 6008, SV 0241 WA, and Charismatic.
Those varieties with more that 35% of the melons harvested in the 45-count class included XWT 6008, ORS 6260, Kingman, 7197, ORS 6253, Charismatic, SV 0241 WA, and Secretariat.
Varieties with high percentage of small fruited melons (60-count) included ORS 7033 B, Secretariat, ORS 6151, 9651 and Kingman.
Varieties with high numbers of 36-count fruit were Captivation, 9601, Road Trip, Unbridled, Charismatic, and Wolverine. Bottle Rocket, SV 3105 WA, ORS 6305, ORS 6278, and Maxima produced over 30% in the 30-count class (very large melons).
Two small fruited “mini” melons, Mini Bee and ORS 7033 B were also tested. They had the highest number of fruits at 8,931 and 9,968 melons per acre respectively. Mini Bee produced over 80% of its melons in the personal or icebox size class from 4 to 9 pounds. ORS 7033 B produced 41% of its melons in the small size class.
There were significant differences in soluble solids among the varieties which is a measure of sweetness. Road Trip, 9651, Turnpike, Unbridled, ORS 6260, Kingman, 7197, Embasy and Captivation had the highest soluble solids levels. All of the varieties had average soluble solids of over 10% with the exception of XWT 6009 and ORS 9033 B.
Hollow heart defects can render watermelons unsaleable. No hollow heart was observed in Mini Bee, Joy Ride, ORS 6260, ORS 6278, ORS 6305, ORS 6253 and Summer Breeze. Turnpike had high levels of hollow heart. Those additional varieties with one or more fruit with major or severe hollow heart (10% unsaleable) were SV 0241, and 9601.
Trials will also be conducted in 2018 and growers are invited to visit the trial during the season. Results from this year’s trial can be found on-line at: http://extension.udel.edu/ag/vegetable-fruit-resources/vegetable-small-fruits-program/
Crunchy Red, an older variety that did very well in 2017
9651 a high yielding dark rind type
Turnpike did well in 2017
Warrior, a lighter rind type with good interior color
Fascination, current industry standard
Red Amber, a new entry into the watermelon market