ISSN:
1871-4528
Keywords:
vecteurs
;
Aphis nasturtii
;
résistance aux virus
;
traitements insecticides
;
traitements huiles minérales
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Description / Table of Contents:
Summary PVM and PVS viruses have a worldwide distribution. Present day cultivars are not resistant to PVM and their resistance to PVS is variable. Little yield loss results from infection by both viruses but symptom expression caused by PVM can result in downgrading of seed crops. A survey of the bibliography shows that most authors believe that PVS transmission is by aphid but differences exist between virus isolates. Species know to be vectors of PVM and PVS are listed in Table 2. Kostiw has demonstrated thatAphis nasturtii can best transmit the two viruses but this result is disputed by other workers. Table 1 and the results of Turska (Fig. 2, Table 2) show that spread of PVS is by vectors, a fact which is not in doubt in the case of PVM, and that the environment (temperature and humidity) has an effect on tuber infection (Table 3). The results summarised in Fig. 3 demonstrate that, although infection level can fluctuate, it generally increases during the growing season for two cultivars over a period of several years. Infection incidence falls sharply with increasing distance from the inoculum source (Fig. 4). Resistance associated with plant maturity to the two viruses increases more slowly than in the case of PVY (Fig. 5). Therefore, bicyclic transmission (the primary infection acting as a source within the same growing season) is more likely to occur than with PVY. New genetic sources of resistance to PVM would allow the breeding of resistant cultivars. Cultivars resistant to PVS have been recognised already for a long time. The only methods to produce PVM- and PVS-free seed are by clonal selection and microprogation. Roguing is inefficient in that instance. Treatment with insecticides is not very effective as with all non-persistant viruses (Fig. 4, Table 4) but with mineral oil the results are clearly more promising (Table 5). Tuber infection by PVM and PVS is reduced especially in early maturing cultivars by haulm destruction as can be seen in Fig. 6 in the case of three cultivar with different resistance levels subjected to different inoculum potentials over a three year period.
Notes:
Résumé On peut considérer que le virus M et le virus S sont très proches du point de vue épidémiologique. Le virus M migre plus vite que le virus S vers les tubercules. Les différences de résistance entre cultivars sont plus grandes pour le virus S que pour le virus M. On constate de grandes différences d'efficacité de transmission d'isolats des 2 virus par les pucerons. Il existe une ressemblance générale au niveau de la transmission entre les deux virus et les autres virus de stylet de la pomme de terre. L'infection par le virus M et le virus S dépend, comme celle par les autres virus de la pomme de terre, en premier lieu de la pression des vecteurs, de la résistance des cultivars et de la quantité d'inoculum dans le milieu.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02361860
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