Performance.

‘Gumbo’ and four standard southern highbush blueberry cultivars—‘Jewel’ (USPP 11,807), ‘Star’ (USPP 10,675), ‘Pearl’ (Stringer et al., 2013), and ‘Santa Fe’ (USPP 10,788)—were established in 3 three-plant replicates in 2003–04 and were evaluated over 8 years (2009–16) near Perkinston, MS (lat. 30.7822° N, long. 89.1428° W) in south-central Mississippi. Plants were grown in a McLaurin sandy loam soil (pH 5.2) amended with 200 m³ pine bark per hectare using recommended production practices, including drip irrigation and fertigation (Braswell et al., 2009). Observations were made on plant and berry attributes, including bloom and ripening dates, and subjective measurements were made on productivity, berry color, berry scar, and flavor each year from 2009 to 2016. Data from each replicate were pooled to provide attribute values for each respective year and were subsequently used to calculate mean ± se. Laboratory measures of berry size, soluble solids content, pH, berry firmness, and berry splitting tendencies were acquired from 2010 to 2016.

The blooming and ripening period of ‘Gumbo’ was similar to ‘Santa Fe’, but was 1 week and 2 weeks later than ‘Star’ and ‘Jewel’, respectively, and 10–14 d earlier than ‘Pearl’ (Table 1). Observations demonstrated that ‘Gumbo’ plant vigor was comparable to ‘Santa Fe’, and greater than other cultivars tested. ‘Gumbo’ productivity was comparable to ‘Star’ and greater than the other comparison cultivars. However, some of ‘Gumbo’s yield advantage may be attributed to the fact that the slightly earlier blooming periods of ‘Star’ and ‘Jewel’ exposed them to late-spring frost events and subsequent flower-bud injury and yield reduction. In comparison to ‘Star’ and ‘Jewel’, berries of ‘Gumbo’ had a visibly lighter blue color, but berry color was comparable to both ‘Pearl’ and ‘Santa Fe’. Picking scars were generally small for all cultivars, but those of ‘Star’ were slightly larger. Berry flavor values were comparable for most cultivars, although soluble solids content of ‘Gumbo’ was less (Table 2). ‘Gumbo’ flavor was found to improve when berries were allowed to hang for several days after attaining their light-blue color.

Table 1.

Observations on fruit and plant characteristics of ‘Gumbo’ and selected southern highbush cultivars at Perkinston, MS, 2009–16.

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Table 2.

Berry quality attributes of ‘Gumbo’ and selected southern highbush blueberry cultivars at Perkinston, MS, 2010–16.

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Laboratory measurements of berry attributes were made from samples collected from each of the three replications of each cultivar from 2010 through 2016, and data were pooled to calculate mean ± se. Berry size was determined by weighing 30 berries of each cultivar and subsequently calculating the average berry weight. Soluble solids content and pH were determined from juice extracted from a puree of a 40-g sample placed into a commercial Waring^® blender (Dynamics Corp. of America, Hartford, CT) and strained through cheesecloth. A hand-held temperature-compensating refractometer (AR 200, Leica Microsystems, Welzar, Germany) was used to measure juice. Soluble solids concentration pH was measured using an AR20 pH/conductivity meter (ThermoFisher Scientific Corp, Waltham, MA). Berry firmness measurements were obtained from 20 berry samples run on a Firmtech II (Bioworks Corp., Stillwater, OK), an apparatus that measures firmness in terms of the rate (grams per millimeter) at which force increases as berries are squeezed and deflected. Tendencies of berry splitting were measured by soaking 50 fully ripe berry samples in distilled water for 24 h and counting the number of split berries (Marshall et al., 2008). Berry weight of ‘Gumbo’ was comparable to that of both ‘Star’ and ‘Jewel’, and greater than ‘Santa Fe’, but less than ‘Pearl’ (Table 2). Soluble solids content ‘Gumbo’ berries was comparable to that of ‘Star’, but less than the other cultivars; pH values were similar for all cultivars. Berry firmness of ‘Gumbo’ was less than ‘Pearl’ or ‘Santa Fe’, comparable to ‘Star’, and greater than ‘Jewel’. Physiologic splitting values were low for all cultivars except ‘Santa Fe’.

Prominent attributes of ‘Gumbo’ are high plant vigor, early berry ripening, good productivity, large berry size, and light-blue berry color. ‘Gumbo’ is expected to perform well not only in the Gulf Coast region of the United States, but also in other areas where southern highbush blueberry cultivars with low to moderate chilling requirements are grown successfully. ‘Gumbo’ should be planted with other southern highbush blueberry cultivars with similar blooming periods to facilitate pollination and fruit set, such as ‘Camelia’ (USPP 18,151), ‘Rebel’ (USPP 18,138), ‘Santa Fe’ (USPP10788P), and ‘Star’ (USPP 10,675). No disease symptoms were observed on ‘Gumbo’ during the evaluation period.

Propagation.

‘Gumbo’ propagates readily from softwood cuttings taken after new growth flushes in late spring or late summer, as well as from hardwood cuttings taken in the winter. Rooted cuttings grow vigorously in the nursery.

Availability.

‘Gumbo’ is released unconditionally, with no warranty given regarding its performance or adaptation under specific environmental or cultural conditions. The USDA-ARS has submitted a patent application for this cultivar and it will become available for licensing. Nurseries interested in this new cultivar should contact the Mississippi State University Office of Technology Management, 60 Technology Blvd., Suite 115A, Starkville, MS 39795. Researchers interested in evaluating ‘Gumbo’ may also request information regarding testing under a Material Transfer Agreement.