 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.