by: Dr. Harlene Hatterman-Valenti
‘Dakota Primus’ and ‘Radiant’ are two new releases from the North Dakota State University Grape Germplasm Enhancement Project. Both have been tested at multiple locations and have surpassed common commercial varieties in terms of yield components and winter survival while producing fruit with chemical composition appropriate for wine production (Brix, pH, and titratable acidity). Wine notes and scoring have been favorable, indicating their potential use in commercial wine production.
‘Dakota Primus’ and ‘Radiant’ have rather large clusters with an average weight of 175 g and 125 g, respectively and medium to large berry size with an average weight of 2.1 g and 2.5 g, respectively. Canes of ‘Dakota Primus’ can bear three or more fruit clusters, though they frequently produce only two clusters. Compared to control vines, both ranked favorably for cluster mass in North Dakota.
Both have berries that have a no observed to very low susceptibility to berry splitting or berry shelling. The berry skin color of ‘Dakota Primus’ is 2B to 9A transitioning to 65A to 77B with greater sun exposure, while ‘Radiant’ berry skin color is 149B to 149A ripening to a more golden 154A to 154B.
The harvest date at Fargo for ‘Dakota Primus’ was between 8/12 and 9/16 with the average fruit soluble solids content of 20.3%, pH of 3.4, and titratable acidity of 8.8. The harvest date at Fargo for ‘Radiant’ was between 8/24 and 9/24 with the average fruit soluble solids content of 18.1%, pH of 3.25, and titratable acidity of 11.1.
Both have low susceptibility to powdery mildew, downy mildew, black rot, foliar phylloxera, and no observed grey mold. ‘Dakota Primus’ is mildly susceptible to crown gall and phenoxy herbicide drift while ‘Radiant’ has no observed crown gall and low susceptibility to phenoxy drift.
High winter survival of these accessions in Fargo indicates substantial cold hardiness for both cultivars. Under very challenging conditions at the NDSU Horticulture Research Farm near Absaraka, ND in 2018-2019, both accessions exceeded the survival of all control vines except ‘King of the North’.
Wine made from fruit of ‘Dakota Primus’ has apple, citrus, stone fruit, grapefruit, and tropical fruit flavors and aromas. It has good body, a light peach to straw yellow color, and a low propensity for oxidation. Wine made from fruit of ‘Radiant’ has pear, melon, watermelon, apple, and citrus flavors and aromas. It has a light yellow to gold color and considered well balanced with a low propensity for oxidation. Both accessions carry their low acidity from fruit into the wine regarding malic acid values. However, continued fermentation practices likely require investigation.