Term for bilious, yellowish and two to four millimeter large tumors in a bird's beak-like shape (nodular = nodular), which at phylloxera can be induced on the young, as yet unwooded roots. You are much more dangerous than that tuberosities (scabby swellings on old roots) usually relatively harmless. Nodosities are also present in large numbers in most American species such as Vitis cinerea var. Helleri (Vitis berlandieri), Vitis riparia and Vitis rupestris formed, but a phylloxera infestation does not induce tuberosity there. As long as only nodosities are formed, the survives Rebstock the phylloxera infestation mostly relatively unscathed.
This does not only apply to the American, but also for the European species. However, the vine lice can feed very well on the nodosities and multiply in large numbers and then also attack older roots if necessary. Refined vines tolerate the phylloxera, but they are therefore not free of it, but may even show a very high degree of infestation without causing root damage. Therefore, the susceptibility to nodosities when selecting new ones documents previously not respected or not enough.
Since there are fears that more aggressive rebel strains could soon develop, which could also damage the roots of refined vines, an attempt is made to breed more phylloxera-resistant documents. The two species are particularly suitable as crossing partners Vitis rotundifolia and Vitis cinerea which, in contrast to most of the others mentioned above, neither form nodosities nor tuberosities, i.e. completely resistant are so that the phylloxera can no longer feed on its roots. Since the grafting on Vitis rotundifolia rootstocks does not work, scions Vitis cinerea is increasingly the focus. One of the few documents that have already been tried and successfully introduced in practice, based on the species Vitis cinerea with complete phylloxera resistance, is the Börner variety, which according to its breeder Carl Börner (1880-1953) and is named by Dr. Helmut Becker (1927-1990) was tested and introduced. This underlay is 100% phylloxera-resistant, but also very sensitive to lime and can therefore only be used on lime-poor floors.