White Riesling grapes (L) and leaf. Photos by Patty Skinkis, Oregon State University.
Relatively cold hardy. Makes excellent quality still and sparkling wines. The wines can have intense fruit aromas of apricot or peach. Wine styles range from dry to very sweet dessert wines. The highest quality is achieved when the grapes are grown in the cooler production areas. Well suited for the production of late-harvest dessert wines.
Riesling is primarily grown in Germany, particularly in the Rhine and Moselle regions. It has been grown in California since the late 1800s.
One of the most cold hardy of the vinifera grapes. Tight clusters make for bunch rot problems. Relatively late harvest date. The retention of acidity through the very late stages of ripening allow the grapes to become concentrated by dehydration and still retain sufficient acidity to balance the high residual sugar.
More testing needs to be done, but it does show some promise in Oklahoma as long as diseases can be controlled.
Although used in certain parts of the world to make extraordinary, late-harvest “botrytized” dessert wines, Botrytis infections of Riesling (and other) grapes grown under Indiana conditions do not normally constitute desirable “noble rot.” Riesling’s susceptibility to bunch rot dictates the use of additional canopy management techniques such as leaf removal and extra sprays.
Widely planted. New York White Riesling wines are probably superior to any except those of its homeland in Germany. White Riesling quite reliably reaches the maturity levels commonly chosen in Europe (17 to 20 percent soluble solids) for the variety. The bunch rot susceptibility suggests that extra canopy management techniques such as leaf removal and extra sprays to combat bunch rot may be advantageous. Several excellent clones are available, but avoid older non-virus tested ones, as they have reduced production potential in comparison to certified clones.
STRENGTHS. Riesling grapes are among the most cold hardy of the V. vinifera grapes commonly grown in this region. Like other vinifera varieties, Riesling is subject to occasional cold injury. Riesling vines, however, often survive cold episodes that injure or kill other vinifera vines. Late bud break gives some insurance against frost injury. Riesling breaks bud in the spring anywhere from 5 days to 12 days after Chardonnay. That delay may be of benefit at sites subject to occasional frosts.
WEAKNESSES. The long-term demand for Riesling by wineries is questionable; Riesling grape prices tend to be somewhat lower than those paid by wineries for other vinifera grapes in Virginia. Compact clusters and high susceptibility to berry cracking can lead to severe rot problems, particularly when rains occur just before harvest. Open, divided trellising systems are helpful, but do not eliminate the problem.
Riesling productivity is among the lowest of commonly grown varieties in Virginia. Research in Virginia indicated that in many vineyards, low productivity can be attributed to bud necrosis, which is the abortion and drying of buds during the summer of their development. The causes are not known, but research has shown high rates of shoot growth and poor light exposure of the developing buds increase the incidence of necrotic buds. Cordon training and spur pruning are used in Virginia to compensate for bud necrosis because the first few buds of the cane are often unaffected.
Riesling is most commonly grown in the cooler production regions of California, with the majority of acreage found in the Central Coast. Vine yield can vary considerably by climatic region, site influences, and cultural practices. Crop size can range from 4 to 8 tons per acre. Riesling tends to overcrop when it is grown on deep, fertile sites.
The National Grape Registry (NGR) contains information about varieties of wine, juice, and table grapes, raisins, and grape rootstocks available in the United States. Growers, nurseries, winemakers and researchers can find background information and source contacts for those grape varieties in this single convenient location.
Information contributed by:
Bruce Bordelon, Purdue University
Eric Stafne, Oklahoma State University
Bruce Reisch, Robert Pool, David Peterson, Mary-Howell Martens, and Thomas Henick-Kling, Cornell University
The Mid-Atlantic Winegrape Grower's Guide
University of California Integrated Viticulture program