Viticulture is the study, science, and production of grapes, especially for the purpose of wine-making.
Located in the southern tip of Spain, where we live, is the wine production region identified as the “Jerez-Xérès-Sherry” Denomination of Origin (D.O) and also that of “Manzanilla-Sanlúcar de Barrameda.” The “Sherry triangle” is formed by the cities of Jerez de la Frontera, El Puerto de Santa María and Sanlúcar de Barrameda, although the Denomination of Origin also includes land in the municipalities of Chipiona, Trebujena, Rota, Puerto Real, Chiclana de la Frontera, and specific areas of Lebrija. This area is the “terroir” where the raw material for our sherry wines will be grown. “Terroir,” a French term, refers to vineyards in the same region and belonging to a specific D.O., which share the same type of soil, weather conditions, and grapes. All together, these factors contribute to the specific personality which a wine, produced from that area, will have.
The climate of the Sherry Triangle region, in general, is warm. Summers are hot and dry sometimes reaching temperatures of over 40ºC. Those temperatures are strongly influenced by the proximity of the Atlantic Ocean whose damp westerly winds, the “viento de poniente”, bring moisture from the sea to the vines. This moisture then falls on the vines in the form of an early morning dew, called “rocío,” which creates a moderating influence on the summer´s heat and the hot easterly wind, which is called the “viento de levante”. Winters are mild and the temperatures rarely drop below OºC.
The region enjoys almost 300 days of intense and direct sunlight per year. The average rainfall is 600 lit/m2, most of which falls between the months of November and March. This rainfall contributes to the groundwater reserves that the vines draw upon in the dry summer months. The month of September, close to the harvest season, is normally dry. This is a positive factor in the grape’s ripening process and in its general quality. The region experiences neither frosts nor hail. These climatic conditions favor both the optimum development of the vines and a perfect ripening of the grapes right up to the moment they are harvested.
The Sherry Triangle wine region is an area of open and rolling hillsides. It´s soil is known as “albariza” (from the Latin
word “alba” meaning white). It is a deep, chalky soil which is rich in calcium carbonate, clay, and silica which are remnants of shells and sea creatures which were present in the sea that once covered this region during the Oligocene period. Even though the albariza is not very rich in nutrients, it is very porous and highly retentive of moisture. This serves to lock in the winter´s rainfall in order to nourish the vines during the dry summer months. This soil is perfectly suited to the growing of grapes for the production of Sherry Wine.
THE VARIETIES OF GRAPES As per the regulations of the Consejo Regulador, (the Controlling Authority for the production of wine in this region) the varieties of grapes which are suitable for the production of Sherry are: Palomino, Pedro Ximénez and Moscatel. All three are white grape varieties and belong to the vitis vinífera (wine producing variety) species.
The Palomino grape is a key ingredient in the production of Sherry. 90% of all Sherry wines are produced from this variety of grape. Its cultivation in this region goes back to ancient times and it is regarded as a native species of Andalucía. It is also known as “Listán”. The buds sprout around mid-March and ripen around the middle of August or the beginning of September. The sugar content reaches around 11º Baumé ( a scale which measures the sugar content in a wine and future content of alcohol) and has low acidity. The grapes are round, medium sized, with thin skin and yellowish green color, sweet and flavorful with colorless juice.
This variety is used to produce great quality Naturally Sweet Sherry. It has greater sugar content, up to 12.8º Baume, and higher levels of acidity. These grapes are almost globular, thin-skinned, transparent and soft, producing a very sweet juice. Once harvested, the grapes are left in the sun submitting them to a “drying” process so as to concentrate their sugar content.
The Moscatel grape is also used to produce the naturally sweet Sherry known as Moscatel de Alejandría or Moscatel de Chipiona. It is grown in the coastal area. Its grapes are thick, fleshy, pale yellow with a musky taste. They have a very powerful aroma, and a high sugar content, which produce a very distinct sweet wine.
All of the above grape varieties grow on American rootstock, as do most of all European grape varieties. In 1894, a phylloxera infestation appeared in the Jerez region. The phylloxera is a very destructive insect, similar to an aphid, which attacks the roots of the vines and which was introduced into Europe from the eastern United States in the mid-19th century. Within 25 years it had almost destroyed the grape and wine industries in France, Italy, and Germany. By the time it reached Jerez area, however, the solution to the problem had been identified. The vineyards were saved by the grafting of local vines on to resistant rootstalks of vines which were native to the eastern United States and which were immune to the phylloxera infestation. Since then, the area vines have always been made up of American rootstock with grafts of local vine stock.
In our next article we will explore the VINICULTURE of Sherry Wines, from the vine to the barrel.
Sherry Wine Educator