These roundworms (ova, roundworms, trichinae) are among the most species-rich and most species-rich group of animals in the world, comprising up to 20,000 different species. Most are very small from 0.1 to about a millimeter (the largest species with over 8 m living in the sperm whale placenta). In contrast to more highly developed worms (such as the earthworm) they have no vessels. Usually there are males and egg-laying females, but occasionally also a sexless maiden procreation (Pathenogese). Until maturity, four larval molting will be done. The food intake is through a hollow mouth sting, which moves rhythmically while suckling. They live with numerous species in the soil and also feed on bacteria or mushrooms what a positive element in ecological System of a vineyard soil represents.
It was not until the 1930s that they became the pest of the grapevine recognized, until then one mistakenly suspected the phylloxera, In the vineyard are mainly two groups that directly by feeding damage and indirectly as a virus transmitter for the Rebstock are very dangerous. As direct damaging parasites, the species cause Meloidogyne, Heterodera and Pratylenchus as a defensive reaction of the vine at the root tips Gallen which they then consume. Although this does not have as serious effects as phylloxera, but leads to water stress and insufficient supply with nutrients, These root gallbladders are found mainly in sandy soil. The species Longidorus maximus and Rotylenchus borealis pierce the vine roots without bile formation with their mouth sting, suck and destroy them. The shoots stay in the development back, in extreme cases, the vine dies. From the frequency the damages are rather small.
The much more devastating effect is indirect, that is, by the transmission of dangerous virus, The two species Xiphinema index or in German Stilettelchen (comes only at the grapevine before) and Xiphinema vuittenezi transmit the Grapevine fanleaf virus (GFV), the species Xiphinema diversicaudatum the Arabis mosaic virus (ArMV), both the brushwood disease effect. As a preventive defense measure, the use of nematode-resistant vine documents, These include the American species Vitis acerifolia. Vitis champinii. Vitis cinerea and Vitis mustangensis, An earlier usual fight by nematicides such as B. DBCP (dibromo-chloropropane) is no longer authorized in viticulture.
Nematodes can, however, in the context of Biological crop protection also as beneficials be used, there are special preparations for certain plants or pests such as weevil and owls caterpillars gives. A sachet can contain up to 2.5 million nematodes. The preparation is dissolved in water and sprayed. The resulting living nematodes actively search for the larvae or caterpillars in the soil, infest them and kill them within a very short time.
Graphics: By Uwe Gille - Own Work, CC BY 2.5 , Link
(modified by Norbert Tischelmayer - May 2019)
Nematode: From Agricultural Research Service , Public domain, Link
Black-legged weevil : www.re-natur.de