Olmo grapes arewine and tablegrape varieties produced byUniversity of California, Davis viticulturist Dr.Harold Olmo. Over the course of his nearly 50-year career, Dr. Olmo bred a wide variety of both grapes by means of bothcrossing varieties from the same species or creatinghybrid grapes fromcultivars of differentVitis species.
Over 30 new grape varieties were created by Dr. Olmo and introduced to theCalifornia wine and table grape industries.[1]
Ruby Cabernet is the most notable and widely planted Olmo grape. It is a cross between theVitis vinifera varietiesCabernet Sauvignon andCarignan that was first trialed by Dr. Olmo in 1936 before being released in 1948. The grape is primarily used in blending, adding color and tartness, but producers such asE & J Gallo Winery have produced varietal wines from the grape. According to wine expertJancis Robinson, Ruby Cabernet can have somearomas reminiscent of a youngCabernet Sauvignon with the color of a Carignan but it lacks the structure andbody to produce premium wines.[2]
In California, the variety is widely planted in theCentral Valley where it can withstand the hotcontinental climate of the valley and still produceharvest yields of 6 to 9 tons an acre.[2] Outside of the United States, the variety can also be found inAustralia,Argentina,Chile,Israel andSouth Africa.
Rubired is a hybrid of thevinifera varietyTinto Cão andAlicante Ganzin, which itself is a hybrid ofVitis rupestrisArmon Rupestris Ganzin No. 4 and thevinifera crossingAlicante Bouschet. Trial breeding and testing were completed by Olmo in 1958.[2]
Like Ruby Cabernet, it was bred to produce significantyields in hot climates, and in the California Central Valley it regularly yields 8 to 10 tons per acre. However, Rubired is ateinturier variety withpigmented, instead of clear, juice. Most red wine grapes have clear juice, the red color of wines coming fromextraction of pigment from the grape skins. Rubired was originally intended for producingfortifiedport-style wines, and since the late 20th century, producers in Australia have included it in some port-style blends. Its intensely dark color is often useful in blending to intensify the color of other red wines, but it can also be used to createvarietal wines.[2]
Emerald Riesling is a white wine grape crossing between thevinifera varietiesRiesling andMuscadelle. Trials on the variety began in 1936 and the variety was released in 1948 at the same time as Ruby Cabernet. Unlike many of the cool-climate Riesling crossings produced inGermany at facilities likeGeisenheim Grape Breeding Institute, the Emerald Riesling was bred for warm climates like theSan Joaquin Valley of California where today more than half of all Emerald Riesling plantings are found. Outside of California, there are limited plantings in South Africa.[2] It is also used quite extensively in Israel, where big wineries use it to produce light, and aromatic - usually off-dry - wines. It comprises roughly 2.6% of the total grape production in Israel, totaling (in 2012) 1,408 tons.[3]
According to wine expert Jancis Robinson, Emerald Riesling produces an aromatic, highacid wine that does not quite have the flavor definition more commonly associated with Riesling or its cool climate crossings. In cooler climate areas where it has been planted, such as theMonterey AVA, it can share some traits with Riesling but with a distinctly fuller body.[2]
Emerald Riesling is also known under the synonyms California 1139 E 29, Emerald Rizling, and Riesling Izumrudnii.[4]
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