Fungal disease (Oidium); see under powdery mildew.
Name for two dangerous vine diseases caused by fungi. They were first introduced to Europe in the second half of the 19th century with contaminated vine material from North America. Both types of fungi are biotrophic parasites, which means that they feed on the living cells of the infected host. The two powdery mildew diseases are often confused, not so much because of the disease symptoms, which are quite clear, but because of the confusingly similar names. There are plant-specific mildews, e.g. for apples, peas, cucumbers, roses, spinach and vines. The fungi are strictly host-specific, meaning they can only live on their host.
Both are conventionally controlled with sulphur (powdery mildew) and copper sulphate or Bordeaux broth (downy mildew). Increasingly, however, special fungicides or plant strengtheners are also being used. Control must often be carried out several times during the growing season. When crossing new varieties, resistance to both types of fungus is nowadays also emphasised. It should be noted that some species of ladybird, which are among the most important beneficial insects in viticulture, feed exclusively on powdery mildew. However, this is of no significance in vineyard control.
Powdery mildew is also called "Oidium" or "Oidium tuckeri" after the gardener William Tucker, who first discovered the fungus in England in 1845. The causative agent of the disease belongs to the tubular fungi (Ascomycota), the botanical name is "Erysiphe necator var. necator" or "Uncinula necator var. necator". The fungus was identified and described in North America as early as 1834. It was probably introduced to Europe via England in the early 1840s and subsequently spread rapidly across the entire continent. This, together with phylloxera, which also originated in North America a few years later, led to a true catastrophe in European viticulture. Large areas of vineyards were destroyed in many countries. In 1854, due to the damage caused by powdery mildew, only one tenth of the normal quantity could be harvested in France. Later, two other...
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