The numerous enemies of the grapevine are divided into the groups of micro-organisms such as bacteria, fungi and viruses, as well as animal pests, which act indirectly through the transmission of diseases or directly through, for example, root feeding or consequential damage such as rot. In addition, some diseases are also caused by nutrient deficiency. Many diseases are of European origin, some were "imported" by America from the middle of the 19th century onwards. These were, in this order, phylloxera, powdery mildew (oidium), downy mildew (peronospora) and black rot (which were called the "four great plagues"), and only in the 1940s were flavescence dorée (golden yellowing).