Grapevine plant named ‘KE-wz1’

Genus and species:hybrid.

Variety denomination: ‘KE-wz1’.

N/A

N/A

Grapes are the fruits of deciduous vines of the botanical genus. Grapes can be consumed as fresh fruit (table grapes) or they can be used to create a wide variety of food products, the most important being fermented grape juice—AKA ‘wine’. California is one of the world's major wine producers. The story of wine production in California is long and interesting. The Spanish missionaries in the 18th century recognized that the Californian climate was ideal for wine production, but it was not until the 19th century that the suitability of California for the production of fine wines was recognized. An early pioneer in this effort was Agoston Haraszthy, a Hungarian nobleman who first tried to establish European wine grapes on Long Island, NY where the climate proved inhospitable for European grapes. His second attempt was in Wisconsin where some of his efforts still survive. Finally, he moved his operations to Sonoma, CA where he established California fine wine production. He introduced cuttings of many of the fine European wine varietals to California. This proved to be extremely fortuitous for the history of American as well as European viticulture. When a majority of the European vineyards were wiped out by phylloxera, it was cuttings from Haraszthy's vineyards that were used to reestablish many of the European vineyards.

One of the quintessential grape varieties in California is the red variety known as ‘Zinfandel’ (not patented). Although it was suspected that this variety was introduced by Haraszthy, it could not be assigned to one of the European varieties, so it was long assumed to be a hybrid originating in California. It was only with the advent of DNA genotyping that it was established that ‘Zinfandel’ is identical to the Croatian variety ‘Crljenak Kastelanski’ (not patented) which was also transplanted to Italy at about the same time it was taken to California. In Italy, the grape is known as ‘Primativo’ (not patented). As is understood by viticulturalists and enologists, clonal selection of grape varieties results in propagation of subtle somaclonal variations, so that a typical ‘Zinfandel’ vine in California may be subtly different from ‘Primativo’ or ‘Crljenak Kastelanski’. Therefore, the present inventor was excited to find ancient ‘Zinfandel’ vines growing on Santa Cruz Island, one of the Channel Islands off the coast of Southern California. These vines were planted in the 19th century and have been long isolated from other vineyards and are, hence, believed to be close to the original ‘Zinfandel’ clone introduced into California in the 19th century.

‘Zinfandel’ is a red grape that produces a dark and intense red wine. It has a long history of use in various Californian red wine blends. More recently, “white zinfandel” wine has been produced by removing the seeds and skins from the wine must before fermentation has taken place. Often, “white zinfandel” wine is sweet and relatively bland because it contains few tannins and flavor elements from the grape skins. Therefore, there is a considerable need for a Zinfandel grape with little or no skin coloring. This would allow production of “white zinfandel” with an improved taste profile.

The present invention relates to a new and distinct grape cultivar named ‘KE-wz1’ that was grown from ‘Zinfandel’ seeds planted in 2014. These seeds resulted from open pollination of the Channel Island ‘Zinfandel’ vines mentioned above. Genetic testing has confirmed that the pollen as well as the seed parents of the new cultivar were ‘Zinfandel’. It was considered that the long isolation of the parent plants on the Santa Rosa Island might have allowed interesting mutations to accumulate in the plants. The inventor was surprised and pleased to discover that several of the vines growing from the planted seeds produced white fruit (i.e., the skins are essentially colorless, allowing the green or yellowish flesh of the berries to show through). Otherwise, the vegetative characteristics of these seedlings were similar or identical to ordinary ‘Zinfandel’. Namely, the vine is characterized by medium to large, deeply five-lobed leaves with prominent triangular teeth, dense hairs on the underside, and produces conical clusters of berries that often have a visible stylar scar. The seedling having the most favorable fruit color and vegetative vigor was selected as the new cultivar ‘KE-wz1’. That vine was asexually propagated from hardwood cuttings. The asexually propagated plants were grown at Rusack Vineyards in Santa Barbara County, California. The propagated plants show no significant variation and are identical to the originally selected ‘KE-wz1’ cultivar. The characteristics and distinctions of this cultivar came true to form and were stable over succeeding generations of asexual reproduction.

The following detailed description of the ‘KE-wz1’ grapevine plant is based on the originally identified plant, and asexually reproduced progeny grown on a vineyard in Santa Barbara County, California. The plants depicted in the figures are approximately 4 years old, having been propagated from hardwood cuttings taken from the original seedling in 2017 and planted in 2018. Generally, except for the fruit color, the new cultivar closely resembles ‘Zinfandel’ (not patented).

Certain characteristics of this cultivar may change with changing environmental conditions (e.g., soil type, light, temperature, irrigation, etc.), nutrient availability, or other factors. Listed measurements are expressed as an average of measurements taken from several individual plants of the new cultivar. The first fruit produced was observed in 2017. Color descriptions and other terminology are used in accordance with their ordinary botanical descriptions, unless the context clearly indicates otherwise. Color code designations are by reference to The Royal Horticultural Society Colour Chart (R.H.S.), Sixth Edition (2015).

Small test batches of wine were produced from the initial plantings. The inventor was pleased to find that the fruit accumulated a high level of sugar (in excess of 25 brix) and yet maintained a high level of acidity while expressing aromatic compounds typical of wines described as “aromatic whites.”

The new cultivar ‘KE-wz1’ is distinguished from its parent ‘Zinfandel’ (not patented) primarily by fruit color. While ‘Zinfandel’ produces dark purple-black berries, ‘KE-wz1’ produces berries with essentially colorless skins that appear yellowish-green due to the underlying flesh color showing through. This distinction is stable and consistent across multiple seasons and asexual propagations.

In all other vegetative and growth characteristics, ‘KE-wz1’ closely resembles ‘Zinfandel’, including:

The key distinguishing features of ‘KE-wz1’ are: Berry skin color: Yellowish-green (RHS N144A) vs. dark purple-black in ‘Zinfandel’; Wine production potential: Naturally white wine without skin separation vs. red wine production in ‘Zinfandel’; Aromatic profile: Enhanced aromatic white wine characteristics vs. typical red wine profile of ‘Zinfandel’