ISSN:
1570-7458
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Description / Table of Contents:
Summary In the course of comparative investigations of the significance of the infestation flight of Aphis fabae Scop. on the distribution of virus diseases, the virus infection which is frequently different on the edges and in the centre of virus diseased potato fields, has been analysed in the potato degeneration area (i.e. where seed potatoes cannot be grown year after year due to the high incidence of virus) of Middle Germany (Quedlinburg) and in the seed growing area of Northern Germany (Groß-Lüsewitz, Mecklenburg). In 1956 a nearly square plot of 500 healthy Ackersegen plants was kept free from apterae (aphids) by a weekly treatment with insecticides (Wofatox spray) and in 1957 the following generation (from 5 by 5 tubers taken separatedly from each bush) was tested for virus infection. The infection was found to be by 12 times more frequent in the degeneration area than in the seed production district. This can only have been due to the visits of alate vectors, especially Myzus persicae Sulz., the infestation flight of which was 29 times greater in Middle than in Northern Germany. In both places the virus infestation in the test plots was observed to decrease quickly from edge to centre. At Quedlinburg the third row showed barely one half of the infestation of the edge and the 5th row only one third of the infestation of the outer rows. At Groß-Lüsewitz it dropped to a tenth in the second row. This phenomenon is due to the nature of the infestation flight of the vectors, which glide extremely near to the ground. The flight is stopped at the bordering rows because of the density of the crop, effecting a far higher infestation rate here than in the centre, where it penetrates only very sparsely. This was evident from an experiment on planting times, described by v. Bernuth 1948: The later the potatoes grow up, the smaller is the virus infestation quotient edge to centre, for when the plants are all small the whole crop is equally exposed to the infestation flight of the vectors, which begins by the end of June. From this experience the demand of agricultural practice for the earliest possible planting and quickest possible covering of the ground by crop is be easily unterstood.
Notes:
Zusammenfassung Versuchsparzellen von Ackersegen-Kartoffeln in Nord- und Mitteldeutschland wurden durch wöchentliche Insektizidbehandlungen während der gesamten Vegetationsperiode 1956 frei von Blattlauskolonien gehalten. Prüfung des Nachbaus auf Virusverseuchung 1957 ergab, daß die Bestände 1956 dennoch Virusinfektionen erhalten hatten, daß der Grad der Verseuchung mit der örtlichen Flugintensität der Vektoren (Myzus persicae Sulz.) in enger Beziehung stand und daß dabei die Randreihen bedeutend mehr Infektionen aufwiesen als die Mitte der Bestände. Diese Befunde werden mit dem Flug- und Wirtswahlverhalten der geflügelten Vektoren interpretiert.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00344518
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