Resistance of a living organism to damage, in particular due to infections and poisoning, but also environmental conditions (in contrast, immunity means a complete defense mechanism or insensitivity). In viniculture there are four main points where (depending on location and climate ) a resistance of varieties are very important that are mushrooms. frost. phylloxera and dryness (see under drought and water stress ). The term tolerance is often used instead in this context. Plants often develop natural resistance to their enemies in very long periods of time, up to several million years, a good example is the resistance of certain American grape varieties to phylloxera, which is multi-stage, or to both types of mildew, The picture shows the difference between a non-resistant and resistant vine when tapping phylloxera sheet, On the left a bag-like one bile with phylloxera and eggs from it, as well as a weak reaction without biliary formation on the right. With extremely resistant vines, there is no reaction at all when tapped.
On the one hand, resistance depends on whether pathogens like bacteria or virus, Poisons or even living beings find the necessary living conditions, as well as on the part of defense mechanisms or by means of defense mechanisms of the organism which take place automatically immediately after the infection. It can be completely to weakly pronounced. Fungus tolerance refers to the fact that the fungal pathogen on the host plant can multiply, but does not damage it or only does so to a small extent. Are the cause glucanases and chitinases are part of the complex defense mechanism of plants. They break down the cell wall building blocks glucan and chitin, which are found in many fungal cell walls, thereby inhibiting or preventing fungal growth. The so-called have a similar effect phytoalexins caused by infestation microorganisms how fungi or bacteria are formed by the vine itself as a defense reaction.
In the breeding new grape varieties or documents Among other things, great importance is attached to a high resistance to fungi and viral strains, to pests (in the case of rootstocks, especially with regard to the phylloxera ) and frost resistance. The picture shows the difference between EU citizens, and Amerikanerrebe when tapping phylloxera at the root. With the completely resistant American vines, there are no swellings ( Nodositäten or tuberosities ) and thus the phylloxera deprived of food. Rather, a protective cork fabric is formed and thereby the penetration of moisture and microorganisms prevented.
Mushroom-resistant grape varieties are particularly popular in Organic (ecological) viticulture asked and are considered PIWI varieties designated. The opens up new opportunities Genetic Engineering, For example, successful trials have been carried out, the variety Riesling to plant two genes of barley and thus confer resistance to fungi. In addition to the large savings in vine protection expenses due to unnecessary control with pesticides and saved working hours, the achievable positive environmental protection achievements should be emphasized. See also a complete listing of all pests and diseases below Vine enemies,
Leaf : By Joachim Schmid, Geisenheim - Self-photographed , CC BY 3.0 de , Link
Root : From Abesadze, Makarevskaja and Zchakaja, Georgia 1930 - from Joachim Schmid, Frank Manty, Bettina Lindner: Geisenheimer grape varieties and clones, Geisenheimer reports 67, 2009, ISBN 978-3-934742-56-7 , GFDL 1.2 , link and link