Frontenac blanc is a genetic variant of Frontenac that became available in 2012. This variety boasts yellow to golden skin and has an earlier harvest date than both Frontenac and Frontenac gris. It can support very high yields while maintaining fruit and wine quality, making it popular among cold climate grape growers and winemakers alike.
Frontenac blanc makes naturally white wines, from clusters averaging 0.3 lb/cluster. It offers flavors and aromas of citrus, pineapple, and other tropical fruit notes with a rich and concentrated mouthfeel.
Frontenac blanc, like the other Frontenac varieties, is extremely cold hardy and can survive cold events down to -35°F with relatively little bud or cordon injury. It can be grown successfully in USDA Zones 4 and some areas of Zone 3.
Frontenac blanc is a high vigor variety.
Bud break and harvest timing
Growers can expect early to midseason bud break for Frontenac blanc, similar to the rest of the Frontenac family. Frontenac blanc is harvested midseason (late September) but can also be harvested in December for ice wine.
The target Brix at harvest is 22-26°. The suggested pH range for Frontenac blanc is 2.9-3.2. The titratable acidity should be between 10-15 g/L.
Because of its semi-trailing growth habit, the best training system for Frontenac blanc is Single High Wire (SHW), but Geneva Double Curtain (GDC) can also be used. There are growers producing Frontenac blanc successfully on Vertical Shoot Positioning (VSP) but the labor costs are significantly increased with no documented fruit quality benefit. Therefore, SHW or GDC are recommended.
Buds and clusters per vine
Frontenac blanc produces about 3-5 buds per linear foot, so spur-pruned vines should have up to 30 spurs at 6-foot spacing. The average cluster weight is 0.3 lb, and vines can support 60-96 clusters per vine. Target a yield of 5-8 tons/acre. Yields up to 10 tons/acre have been reported in Minnesota, but excessive yields may reduce yield or vine health the following year.
Pruning and canopy management
When spur pruning, maintain 3-5 spurs per linear foot and 2-4 buds per spur. Then, shoot thin to 2 shoots per spur once shoots are over 4 inches long. Fruit zone leaf removal and shoot thinning can both be used to promote a balance between vegetative and reproductive growth, and expose fruit to sun to enhance ripening. As with other varieties, practice trunk and cordon renewal as necessary, to minimize blind wood and maximize vine health and longevity.
Frontenac blanc has a high susceptibility to foliar phylloxera. It is moderately susceptible to powdery mildew, black rot, and anthracnose. A spray program for fungal diseases, focusing on bud break through bloom, is important for managing this variety.