the cooler Patagonia region which contains the winemaking provinces of Río Negro and Neuquén, the soil is more chalky. Viticulture The growing season in Argentina usually last from budbreak in October to harvest beginning sometime in February. The Instituto Nacional de Vitivinicultura (INV), the main government controlling body for the wine industry, declares the beginning date for harvest in a region with the harvest season sometimes lasting till April depending on the variety and wine region. A sizable population of itinerant laborers provides an abundance of grape pickers at low cost which has slowed the conversion to mechanical harvesting. After harvest, grapes often have to be transported long distances, taking several hours, from the rural vineyards to winemaking facilities located in more urban areas. In the 1970s, yields were reported as surpassing , a sharp contrast to the average yields in premium wine regions such as Bordeaux and Napa Valley of . As the Argentine wine industry continues to grow in the 21st century, several related viticultural trends will involve improvements in irrigation, yield control, canopy management and the construction of more winemaking facilities closer to the vineyards. Argentina is unique in the wine world for the absence of the phylloxera threat that has devastated vineyards across the globe. The phylloxera louse is present in Argentina but is a particular weak biotype that does not survive long in the soil. When it does attack vines, the damage is not significant enough to kill the vine and the roots eventually grow back. Because of this most of the vineyards in Argentina are planted on ungrafted rootstock. There are many theories about why phylloxera has not yet reach this part of the world. The centuries-old tradition of flood irrigation where water is allowed to deeply saturate the soil may be one reason, as is the high proportion of sand present in the soil. The relative isolation of Argentina is also cited as a potential benefit against phylloxera with the country's wine regions being bordered by mountains, deserts and oceans that create natural barriers against the spread of the louse. Despite the minimal risk of phylloxera, some producers are switching to grafted rootstock that provide better yield control. Various methods of vine training were introduced in Argentina by European immigrants in the 19th and 20th century. The espaldera system combined the traditional method of using three wires to train the vines close to