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Water dissemination of Radopholus similis (Cobb) on nitisol in Martinique

Chabrier C., Mauriol-Bastol C., Quénéhervé P.. 2008. In : 5th International Congress of Nematology. Book of proceedings, July 13-18, 2008, Brisbane, Australia. s.l. : s.n., p. 200-201. International Congress of Nematology. 5, 2008-07-13/2008-07-18, Brisbane (Australie).

New cropping systems have been developed in the French West Indies that combine fallow or rotation crops with nematode-free vitro-plants to avoid the repeated applications of nematicides in banana fields. However, sometimes after only two to four years, the burrowing nematode Radopholus similis progressively reinfests banana fields and causes damages and economic losses again. Among different hypothesis for reinfestation, we studied the possibility that nematodes were disseminated by runoff and leached water from upstream infested fields. At the decimetre scale, we analyzed the dispersion of R. similis individuals on soil surface under a 1 m2 rainfall simulator; water leaching of nematodes was also studied using soil cylinders apparatus in aspersion chambers. At the field scale, reinfestation of nematodes was monitored plant by plant. The experimental field was divided in plots sunounded or not by ditches. Ail studies were conducted on nitisol, which are representative of lowland banana fields in French West Indies. Results show that water runoff is likely to disseminate R. similis individuals over long distance on soil surface when soil moisture is already close to the field capacity. At the opposite, dissemination to soil depth of R. similis is limited: less than 8% of the nematodes reached layers deeper than 10 cm after exceptional rainfails that represent several times the poral volume of the soil. A passive dissemination model could only explain partiaily the distance covered by nematode individuals and not the percentage of dead or non-active nematode which increases with covered distance or soil depth. It seems that R. similis have developed behaviour of escaping leaching. However, from a practical point of view, 50- to 80-cm deep ditches can efficiently prevent R. similis dissemination in banana fields. (Texte intégral)

Mots-clés : radopholus similis; martinique; france

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