Red Jade currants
Red currants range in color from dark red to translucent white. For all practical purposes, they are all the same. Nearly all cultivars grown domestically are the hybrid offspring of three species, each of which provide specific traits. R. rubrum is a cold-hardy, upright shrub, native from northern Europe to Siberia and Manchuria. R.sativum is a spreading shrub from the cool temperate regions of western Europe. R. petraeum, a native to the high mountain areas of North Africa and Europe, contributes vigorous growth and disease resistance. R. sativum is a parent of most of the best cultivars in terms of size and flavor.
This family of species and cultivars likes cool, moist conditions and is best adapted to zones 3-5. They are more tolerant of site and soil conditions than many fruits but prefer heavier, clay-based soils that are slightly acidic (pH 6.0-6.5). Red currants are shade tolerant and will fruit well in partial shade. Red, pink and white currants share most of the characteristics of other ribes as shown in the Ribes Information Summary, but they are less disease prone, with some resistance to white pine blister rust (WPBR) and powdery mildew.
While there are no species differences, color does indicate general cultivar characteristics. Red fruit have more anthocyanin content and can be expected to have more antioxidant activity. They also tend to be more acidic, making them more tart. Vitamin C content and other nutraceutical components are probably similar.
The following cultivar descriptions and observations are grouped by color (red, pink and white). All were planted in 2003 and purchased from four different sources. All eight cultivars had 100 percent survival.
The three true red cultivars at Carandale were selected to represent a range of fruit maturity, fruit characteristics, plant types and disease tolerance.
Jhonkeer van Tets fruit and foliage
‘Jonkheer van Tets’ is the earliest ripening cultivar. The good-sized fruit is dark red and easy to harvest on the medium-length strigs. It is tart, but has good quality for processing. The bush is productive and semi-erect. It seems to have good disease resistance, though some yellowing of leaves and cane death has been observed. With the exception of 2012, it has always had good fruit set and displayed as much frost tolerance as the later blooming cultivars. This would be a good reliable selection to introduce the red currant season. Plants were from Nourse Farms.
Dormant Red Jade plant
‘Red Jade’ is a mid-season cultivar with medium to large bright red translucent fruit. The canes are dense and upright, making pruning a challenge to get good airflow. It is extremely fruitful. Stiff upright canes hold up well even under heavy fruit load. They will lean at a 45-degree angle but seldom lie flat on the ground as the other cultivars do. The fruit is borne on medium length strigs and fairly easy to harvest. Cane length is somewhat shorter than the other red cultivars, which also helps canes stand. Fruit quality is good but not outstanding. It is also more prone to sunburn than the other two varieties tested. With good pruning management, this high yielding cultivar could have economic potential. Plants were purchased from One Green World.
Rovada fruit and foliage
‘Rovada’ is a late blooming and ripening selection with large fruit on long strigs, making it easy to harvest. The fruit is dark red when fully ripe, not excessively tart, and probably best used for jams, jellies, juice, etc. Yields are very good. Plants are somewhat sprawling. Even with selective pruning, fruit-laden canes often lay on the ground, a problem that could be corrected with trellising. Plants are vigorous and show good disease resistance. Under normal conditions, this selection should avoid frost damage because of its late bloom. ‘Rovada’ appears to have economic potential for extending the red currant season by at least two weeks. Plants were from Northwoods Nursery (see One Green World).
Discussion of red-colored cultivars
Probably the most familiar fruit in the ribes genus for most people in the U.S., the red-colored currants are the most tart, and probably contain the highest antioxidant levels, of the red currant group. All three cultivars selected for observation appear to be good candidates for inclusion in an integrated cropping system. Together, they would extend the harvest season five weeks.
In general, pink cultivars have a milder flavor and are sweeter than red, making them edible out-of-hand. Two selections were chosen to represent pink cultivars in the Carandale test plot.
Pink Champagne fruit
‘Pink Champagne’ is an old cultivar but still considered one the best tasting of any red currant. The compact bush appears to be quite disease resistant. The beautiful, translucent pink fruit is suitable for cooking and preserves, as well as fresh eating. It has good fruit yield for the plant size, but it is difficult to harvest. The small compact strigs have short stems that are difficult to remove without damaging the fruit. The lack of fruit per strig is made up for by the density (number) of strigs per cane, adding to the difficulty of harvest. This is especially true of the two- and three-year-old canes where fruit is produced on short spurs. The fruit has a long hang time, but if left on too long, fruit quality decreases and sunburn becomes a problem. ‘Pink Champagne’ is probably best-suited for home gardens or pick-your-own operations, but it has some potential for commercial growers. Plants were purchased from Nourse Farms.
Glorie de Sablons fruit and foliage
‘Glorie de Sablons’ is similar to pink champagne with subtle differences. Fruit has similar appearance and quality but tends to be larger and later ripening. Plants are somewhat larger, but the yield seems to be about the same or less. Strigs are a little larger, but less dense, making them easier to harvest. Disease resistance seems to be about the same. During the 2012 season, the foliage on one of the five plants turned a bright yellow, and canes were pruned back to ground level and removed to prevent the spread of a possible pathogen. Regrowth appeared to be normal, but will be watched closely.
Discussion of pink-colored cultivars
Pink currants could be an attractive and economically beneficial addition to an integrated cropping system, but there will be challenges. There are not enough differences between these two cultivars to make a definitive recommendation. Carandale will continue to observe subtle differences.
In general, the translucent white (colorless) cultivars are the mildest and sweetest of the red currant group. With more white cultivars available than pink, it was possible to observe a wider range of characteristics. Carandale made three selections.
Blanka fruit and foliage
‘Blanka’ is a late blooming white currant not usually affected by frost. The canes are large, vigorous and spreading. It would benefit from trellising to keep canes upright. The fruit is large, opaque, off-white and borne on long strigs that are attractive and easy to harvest. The late-ripening fruit is sweet and somewhat bland, but it has good shelf life. It should yield well due to the size of fruit and large canes, but yields have been inconsistent in the test plot. Some canes produce beautiful fruit, while others (usually the older ones) will defoliate and produce smaller and lower quality fruit, indicating disease susceptability. This could be a very good high-yielding variety in a commercial setting where good management practices are used to scout, identify and treat disease symptoms as needed. Plants were purchased from Northwoods Nursery (see One Green World).
Primus fruit and foliage
‘Primus’ is an earlier blooming cultivar, but frost damage has not been an issue (except for 2012 when all cultivars froze). The vigorous compact bush has good yields of translucent white fruit that is very sweet with excellent, unique fresh flavor. The berries and strigs are smaller (more like pink currants), making them more difficult to harvest than ‘Blanka’. Yield is more consistent than ‘Blanka’, and disease resistance appears to be better. In addition to good flavor, ‘Primus’ is said to have high vitamin C content. Fruit quality alone could make this a good choice for inclusion in an integrated planting system. Plants were purchased from Raintree Nursery.
Swedish White plant
‘Swedish White’ is a lesser known, very productive cultivar. Plant size is between ‘Blanka’ and ‘Primus’. The flavorful, sweet and translucent berries are similar to those of ‘Primus’, with lower quality. The fruit can be hard to harvest because the strigs are densely packed, especially on the two- and three-year-old canes. The stem length of strigs is longer than pink currants in the test plot, which helps offset the density issue. The plants appear to have the best disease resistance of the three white cultivars, and perhaps of all the red currant group. Plants were sourced from Northwoods Nursery (see One Green World).
Discussion of white-colored cultivars
All three white currant selections have merit for commercial production. The choice will come down to what trait is most important at the site and in the intended marketplace. For size, ease of harvest and appearance, ‘Blanka’ would be the choice. For the best fruit quality (sweetness, flavor and vitamin C), ‘Primus’ would be best. For good fruit quality and the best disease resistance, ‘Swedish White’ is the winner.
Discussion of red currant group overall
Red currants have some familiarity in the U.S. and would probably be the easiest member of the Ribes genus to promote as an alternative fruit crop in a local and regional marketing system. They have a clean, crisp taste that is pleasant to the palate. The fruit is visually attractive and can range from sweet to very tart, giving them a wide range of uses. The less tart cultivars are good fresh. More tart varieties make excellent jelly and are often mixed with bland fruits to enhance flavor. Red currants are often used to add color and tartness to sweet or sour sauces, ice cream, yogurt, sorbets, meat/poultry/fish glazes, or as a flavor enhancer (like lemons).
While red currants cannot compete with black currants for vitamin, mineral and phytochemical content, they do rank high in comparison to other commonly grown fruits and vegetables. They are low in calories and high in dietary fiber. Red currants are rich in vitamin C and potassium, and provide iron, magnesium, and trace amounts of phosphorus, calcium and sodium.
Red currants produce abundant nectar and pollen, making them highly attractive to a wide range of pollinators. They are a beneficial ecological addition to an integrated system.