CALIFORNIA AGRICULTURAL EXPERIMENT STATION f MERALD RIESLIN Two New Table-Wine Grape Varieties MAY, 1948 THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA • BERKELEY :ri«: : s«B : i : ;:«s^ Ruby Cabernet and Emerald Riesling are table-wine varieties that show promise of being outstanding in combining high pro- ductivity and wine quality • The grape-breeding program of the University of California was begun in 1929 by the Division of Viticulture. Originating new varieties better adapted to California conditions is one of the main activities of this program. During the ten-year period 1931—1940, a total of 23,658 seedling vines of controlled parentage were planted in the vineyard for fruiting. From these, promising vines are being selected for further tests in trial plots widely scattered throughout California. In some instances, semicommercial trials of the first selections have already been completed. This is the case with RUBY CABERNET and EMERALD RIESLING. • Cuttings of these varieties are not offered for sale or distribution by the University of California, but may be purchased from nursery- men. If you want to know where they may be obtained, write to the Division of Viticulture, California Agricultural Experiment Station, Davis, California. Upper, Ruby Cabernet; lower, Emerald Riesling; both about 2/5 natural size RUBY CABERNET AND EMERALD RIESLING Two New Table-Wine Grape Varieties H. P. OLMO Associate Professor of Viticulture and Associate Viticulturist in the Experiment Station Ruby Cabernet is a hybrid of Carignane x Cabernet Sauvignon, station seedling 234F2, from a cross made in 1936. The vine first fruited in the 1940 season. Of 87 seedlings brought to fruiting and tested, this selection was outstanding in wine quality. The purpose of this cross was to com- bine the excellent viticultural features of the Carignane with the outstanding wine quality of the Cabernet Sauvignon. The Carignane has long been a favorite variety in California because of its vigor and its pronounced upright growth which makes for ease in pruning, harvesting, and other vineyard operations. The fruit clusters are large, resistant to spoilage diseases, and easily harvested. The variety is a consistently heavy bearer. The yield of juice is high, and it ferments without special care. Cabernet Sauvignon, the pollen parent, is universally recognized as the best of all red table-wine varieties in the production of outstanding claret-type wines. It is the base for the fine red wines of the Bor- deaux region. However, because of very low yields and the high cost of produc- tion, the variety can be raised with economic success only under special con- ditions. The tendency in practically all countries has, therefore, been to make use of the name or derivation, but the actual acreage keeps diminishing as higher- Received for publication January 22, 1948. yielding varieties of poorer quality are substituted. This trend is not likely to change, and the best way to keep high quality in our wines is to increase the yielding ability of the finer varieties. Ruby Cabernet is a first attempt to combine high quality and heavy-yielding ability within the same variety. Ruby Cabernet has been tested in two localities, the University Farm at Davis in Yolo County and St. Helena in Napa County. The first area is typical of a sweet- wine-producing section ; summer temperatures are too high for the produc- tion of the best table wines. St. Helena is situated in the north coastal area that produces table wines of good to excellent quality. In the St. Helena vineyard, 7 varieties were planted in 2 randomized blocks; each variety plot of 6 vines was repre- sented once within the block. The same plan was used at Davis, except that each variety had 10 vines per plot. For com- parison, Cabernet Sauvignon was in- cluded at St. Helena and the Carignane and the Cabernet Sauvignon at Davis. Since the new varieties were in the initial stage of selection, a more elaborate plan was not necessary. All of the varieties were field budded on the same selected lot of St. George rootstock in the fall of 1942. Previous to setting up these trial plots, four seasons' data were available on the [4] varieties as individual seedling vines in the breeding block. Very small quantities of wine (usually 1/10 gallon) were made from the fruit for three seasons, 1940, 1941, and 1942. The most promising seedlings from the standpoint of both yield and wine quality were then propa- gated in the trial blocks. The trial blocks first came into bearing in 1944. From then on, enough fruit was used from each plot to make 5 gallons of finished wine. In certain instances dupli- cate samples were run at Davis in 1946 and again in 1947. This was done to get some indication of the reliability of the wine testing and scoring, as well as the variation in fruit composition between plots in the two blocks. The yield records were taken each year on the individual vines. See table 1. Variety appears to combine high quality with large yield Ruby Cabernet greatly exceeded the yield of Cabernet for every one of the four years of record, both at Davis and St. Helena. The yields at Davis in the 1947 season were reduced markedly because of unfavorable weather during the blossom- ing period. In some seasons the yield was two or three times larger. The average yield was not, however, equal to that of the Carignane. The fact that the new Ruby Cabernet can bear over 7 tons per acre of high-quality fruit seems to disprove the widely held opinion that high quality and very low yields must always go to- gether. Tasting and analyzing of the wines were ordinarily completed during March or April following the vintage. Standard methods were employed in the chemical analyses. In most instances tasting of the one-year-old wines was also done at the time of bottling, and some tastings were repeated 6 months or a year later. AH varieties entering the winery were known only by number, so the identity of any variety was unknown to the tasters. The wines were judged and scored from 1 to % %XXXXXXXXXXXXXXXXXXV*<»^XXXXXXXXXXXXXXXXXXXXXXXXXXXV«XVXXXXXXXXXXXXXXXXXXXXXX^ Table 1 YIELDS OF THE RUBY CABERNET COMPARED WITH CABERNET SAUVIGNON AND CARIGNANE ! RUBY CABERNET CABERNET SAUVIGNON TONS PER ACRE 608 VINES DAVIS FIRST BEARING YEAR, 1944 ST. 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O P4UU Pt3 tf O fl < *■ IO co c* *# -* "^ ^ os OS OS os iH iH tH tH 12, by different groups of tasters, some with long experience in evaluating wine quality in the commercial field. A wine rating 5 was considered a standard market wine of good commercial quality. The composite of ratings, usually from 6 to 18 tastings, are the mean values listed in table 2 as the "score." Ruby Cabernet advantageous from grower's viewpoint Ruby Cabernet, despite much heavier production, ripens from 4 to 6 days in advance of the Cabernet Sauvignon. On the same date of harvest Ruby Cabernet was higher in sugar content in the 1944 to 1947 seasons at Davis, but only in the 1944 and 1945 seasons at St. Helena. In all instances Ruby Cabernet ripened well in advance of Carignane in the Davis block. The acidity of the must of Ruby Cabernet was higher than Cabernet Sau- vignon at the same sugar content both at Davis and St. Helena. This is an impor- tant factor in favor of Ruby Cabernet. From the grower's viewpoint, the va- riety has many good features. It buds out late in the spring, only several days earlier than Cabernet Sauvignon. The vine is a very vigorous grower and is productive enough with spur pruning so that more costly pruning systems are not necessary. The habit of growth is open and semi- upright, so that training and pruning are easy. There is no tendency toward over- bearing with normal handling, and the vine retains rather consistent annual growth and fruiting. The fruit clusters are borne on long peduncles, hang free, and are easily located and harvested. The berries are set loosely in the clusters, re- sulting in good exposure and very uni- form ripening. The fruit remains in excellent condition on the vine, and is not injured to any great degree by sunburn or spoilage. The fruit reaches the crusher in excel- lent condition, and the juice yield is much higher than that of Cabernet Sauvignon because of a smaller proportion of skin and seeds in relation to the volume of the berry. The fermentation is easily accom- plished and goes to dryness without taking special precautions. Clearing of the wine takes place rapidly and com- pletely after fermentation, and its compo- sition is such that no lots have ever spoiled with the usual cellar treatment. The wines of Ruby Cabernet appear as sound as those of Cabernet Sauvignon in every respect. The color of the wine is more intense in Ruby Cabernet and ap- pears to have good stability. Its hue is often more reddish. The typical Cabernet aroma is recognizable in the young wine, and the bouquet that is so characteristic of Cabernet Sauvignon develops with aging. Tasters are more likely to recognize the Cabernet characteristics in the new variety than in Cabernet Sauvignon itself. The tasting scores on wines of one and two years of age demonstrate the excel- lence of the finished wine, certainly rating it on a par and often surpassing the prod- uct of the world-famous Cabernet Sau- vignon. The findings of these studies, presented from such small-scale experiments, might justly be criticized. However, a com- mercial winery test during the 1946 season well demonstrates the general ex- cellence of the wine, and tends to sub- stantiate the small-scale tests. Long-time aging tests to determine the ultimate de- velopment and length of life of the wines are in progress, but no comparisons are yet available. The opinions of all tasters are in agreement that Ruby Cabernet matures more rapidly and becomes mar- ketable sooner than Cabernet Sauvignon. Certainly this is a commercial advantage if high quality can still be obtained. Whether this more rapid mellowing in- dicates a shorter life and incapacity to reach a great peak of development with prolonged aging cannot be foretold at present. Description of Ruby Cabernet Vine: Very vigorous, trunk thick, bud- ding out two to three days before Cabernet Sauvignon ; only slightly less susceptible to powdery mildew than Carignane. Canes: Short, thick, round in X-section, well spaced and arising symmetrically ; upright like Carignane until after fruit set, and then arching over until semi- upright; shoots lignifying early and quite resistant to breakage by wind, straight, medium length, light buff, nodes sharply contrasted with dark- brown color, but not much swollen. Buds very dark brown, conical, axis projecting at right angles with cane, sharply pointed but of small diameter, basal portion often strongly appressed or even indented by the tight-clasping leaf petiole. Tendrils thin, few, short, bifid, wiry, only weakly coiled. Leaves: Large, 15.5x18.0 cm; dull as- pect, dark green, distinctly five lobed, outline very irregular ; the median lobe very dominant, elongated and tri- angular, with very broad base, lateral lobes asymmetrical and very often con- torted. Superior sinuses well marked, deep, wide, closed at summits by the overlapping lobes. Inferior sinuses wide U shaped, open. Lower surface of blade sparsely covered with mixture of long floccose hairs and short bristly ones arising on the veins. Teeth large, in two series, obtuse, those on basal lobes often rounded, apical teeth very large, acute, and prominent. In all general characters, leaf very similar to Carignane, but having slightly deeper indentations. Fall coloration wine-red, mottled with yellow, veins remaining distinct green in contrast; leaf fall early, with Carignane. 8 Flowers: Small, ovary small as in Caber- net Sauvignon, filaments very long for size of flower, calyptras shed com- pletely; very subject to drop (coulure j when growth is overly vigorous. Fruit: Clusters medium, primary ones single or doubly winged, 200 to 300 gm, loose to very loose, peduncle thick, woody, very rigid, completely lignified and brown, hanging free and easily harvested. Berry ellipsoidal, size 19 (Cabernet 13, Carignane 22), skin thick; pulp soft, bright green, juicy; adherence very good, pedicel thin, dark green, 7 to 8 mm long, with scattered but large, raised lenticels, very corky at point of attachment but not widely flanged; brush with veins deep purple, firmly attached. Flavor of Cabernet Sauvignon, particularly noticeable be- fore full maturity. Berries with high and uniform seed development, and very resistant to rain damage and fruit rot. Seeds smaller than either parent, 29.6 mg, usually 3 per berry, surface very smooth and symmetrical, beak slender and pointed; chalaza oval, craterlike. EMERALD RIESLING Emerald Riesling is a hybrid of Musca- delle (of California) and White Riesling, station seedling 1139E29. Muscadelle is a variety of unknown origin. It has been found to be characterized by female flowers and, therefore, requires cross- pollination to be fruitful. Emerald Ries- ling came from seed collected in 1935 and was at first presumed to be from self- pollinated clusters of Muscadelle, but it was later apparent that a few berries were set from pollen contamination of the ad- jacent vines of White Riesling. Emerald Riesling was at the outset, in the first year of bearing in 1939, dis- tinguished by its high productivity and healthy foliage, and preliminary wine tests indicated that it gave the most promise of any of 35 seedlings in the population. Emerald Riesling was first propagated for wine trials at Davis in 1939, when 22 vines of rootstock Richter 99 (99-R) were field budded. In 1940, a row of 10 vines was budded on rootstock 1613 at St. Helena. The latter plot was established on heavy adobe soil in a low-lying area subject to spring frosts. During the 1944 season the spurs of all varieties in this block had injured or dead buds. Emerald Riesling was the only variety to give a fair yield from the growth of basal buds that were not injured, averaging 10.9 pounds per vine. The use of rootstock 1613 for this variety gave erratic results, and this plot was abandoned because several vines became greatly dwarfed. The St. Helena data of 1946 and 1947 are from vines propagated on St. George rootstock and in their first year of bear- ing. The average yields in pounds per vine (table 3) were from blocks of over 100 vines each. There were no standard varieties in the same experimental setup to compare with Emerald Riesling. At Davis there was a row of French Colombard on rootstock Teleki 5-A some 220 feet distant from the row of Emerald Riesling. This was one of the most vigorous and most productive rows in the planting, and so a yield com- parison was made with this variety. The annual yields of both varieties when com- pared by the "t" test showed no signifi- cant differences for the four years, 1944 to 1947. Emerald Riesling is certainly, therefore, among the most productive varieties. The musts and wines of Emerald Ries- ling are characterized by high acidity (table 3), and in this respect they re- semble the French Colombard. 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CO CO CO CO CO CO CO +3 02 © M 0) (A en 53 no © tH t- © o oo OS CO CO © t> CO IO H H 00 O n s < o o o o o O O O rl H iH © © © © iH tH s E < bo CM CO CM © © O l> t> cN © © CO t- CO lO © © "3 CD CO CM CM CM © CO *H CM CO CO CM CM CO ^+" © tN CM i-H CM CO CM CO CM CM CM tH CM w CM ^-v i3 t3 a MS 00 CO 1-t CM id CM CO d cm CO © CM O © CO © © i-4 © CO i-H CO © © © V 73 t> os CM iH CM o *H CO t- © lO w iH cN © © © © iH CM +a +a ft ft * © © turity the fruit still remains a deceptive green, even though the Balling is high enough for producing table wine. The grower could easily leave the fruit on the vine past the proper stage for making the best product. The clusters are much more resistant to fruit rots and the attacks of Botrytis than is the Folle blanche. The fruit has always been exception- ally clean and free of spoilage after trans- port. It is easily crushed and stemmed. If the grapes are not overmature, the free-run juice is light green in color, a characteristic maintained in the wine of grapes from the cooler coastal regions. There is a great demand for wine of this color in commercial channels. The juice does not separate readily from the pulp and is likely to be some- what thick, a characteristic of its Musca- delle parentage. This often results in a slow fermentation. In order to complete the fermentation to dryness, too much aeration may be given, which can cause some undesirable oxidation. This has been especially noticeable in the small quantities of must, usually 8 to 10 gallons, that have been handled in the experi- mental lots at Davis. The wines have not scored well in such instances. This seem- ing defect can apparently be easily over- come by the correct cellar treatment, either by handling larger quantities, not using musts too high in sugar, or by blending in a small quantity of juice of a variety easily fermented. In a commercial- winery test, made in the 1946 season, the wine was produced without special care, kept a good color, and cleared rapidly. Tasters who have sampled the wine con- sider it very promising. Nonetheless, the yield of alcohol is high, and the fermentation is clean, even when some browning from overoxidation occurs. Once fermented, the wine becomes brilliant in a short period of time and is quite stable. At first, some tasters dis- count the acidity as being too high, but on aging this sharpness disappears. The best samples in many respects resemble the Chablis of France, being tart and fresh. The wine is heavier in body than either the Folle blanche or French Colom- bard and develops much more character on aging. Preliminary results indicate the wine is long-lived and does not reach per- fection without proper aging. The Davis samples of 1941 are still improving in bottle. Commercial tests seem warranted to determine the suitability of this high- acid variety for the production of cham- pagne. California vineyards lack varieties that produce sound fruit of high sugar and high acidity. Description of Emerald Riesling Vine: Vigorous, bushy, trunk stout, with developed; buds conical, tightly scaled, very dense foliage cover; budding out late, leaf fall very late, very fruitful. Shoots: Very leafy, leaves expanding rapidly, young leaves glabrous, very shiny, bright yellow-green; tendrils very showy, thick, pendant, very long, bifid; continuing growth until very late in the season. Canes: Numerous, medium length, soon becoming procumbent, very light color, straight and often with secondary branching, not striated, nodes not well small, dark brown. Wood maturity very late, basal buds fruitful. Leaves: Large, thick, almost entire, rounded in outline, superior sinuses re- duced to a cleft, inferior sinuses not evident, petiolar sinuses open, very wide, sharp V ; glabrous above and below, very dark green, devoid of lus- ter, blade flat, smooth, nerves thick and very prominent on lower surface. Peti- ole pale green, thick, rigid, short. Teeth in two series, large, very obtuse. [ii] Fruit: Clusters large, 600 to 700 gm; well filled, conical, hanging free, often borne on first, second, fourth, and fifth nodes, very symmetrical, compound but never winged; peduncle thick and only lignified near point of attachment, strong, little tendency to reflex. Berry round, size 20, dark bluish green even when fully mature, pedicel with firm attachment, lenticels few but scattered and very prominent; skin very thick; pulp soft, gelatinous, bright green, not very juicy, high in acidity. Seeds me- dium, usually three or four per berry, partly clinging to the pulp. ACKNOWLEDGMENTS I wish to thank my colleagues of the Division of Viticulture for assistance in the preparation and evaluation of the wine samples and their helpful observa- tions and comments on the new varieties. Many grape growers, processors, and vintners have generously cooperated in testing the new varieties. Among them, I am particularly grateful to Mr. Sam La Fata of St. Helena, who provided and maintained three trial blocks for the test- ing of more than 30 promising new va- rieties at St. Helena, and provided the fruit for the wine tests during the course of the experiment. Without his aid, the selection of the most promising wine va- rieties would have been delayed. Com- mercial wine tests of some of the new varieties were conducted by Mr. John Daniel, Jr., of the Inglenook Vineyard, in 1946, and by the Napa Valley Coopera- tive Winery at St. Helena in 1947. 15/»/-5,'48(A7966s) 12