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Control of Xiphinema index Populations by Fallow Plants Under Greenhouse and Field Conditions

First author: INRA, UMR 1099 BiO3P F-35653 Le Rheu, France; first, second, and fourth authors: Bordeaux Sciences Agro, University of Bordeaux, 1 Cours du Général de Gaulle, ISVV, F-33170 Gradignan, France; third author: INRA, UMR1131 Santé de la Vigne et Qualité du Vin, F-68000 Colmar, France, and Université de Strasbourg, UMR1131, F-68000 Colmar, France; and fifth author: INRA, UMR1355 ISA, F-06903 Sophia-Antipolis, France, CNRS, UMR6243 ISA, F-06903 Sophia-Antipolis, France, and Université de Nice Sophia-Antipolis, UMR ISA, F-06903 Sophia-Antipolis, France.

The dagger nematode Xiphinema index has a high economic impact in vineyards by direct pathogenicity and above all by transmitting the Grapevine fanleaf virus (GFLV). Agrochemicals have been largely employed to restrict the spread of GFLV by reducing X. index populations but are now banned. As an alternative to nematicides, the use of fallow plants between two successive vine crops was assessed. We selected plant species adapted to vineyard soils and exhibiting negative impact on nematodes and we evaluated their antagonistic effect on X. index in greenhouse using artificially infested soil, and in naturally infested vineyard conditions. The screening was conducted with plants belonging to the families Asteraceae (sunflower, marigold, zinnia, and nyjer), Poaceae (sorghum and rye), Fabaceae (white lupin, white melilot, hairy vetch, and alfalfa), Brassicaceae (rapeseed and camelina), and Boraginaceae (phacelia). In the greenhouse controlled assay, white lupin, nyjer, and marigold significantly reduced X. index populations compared with that of bare soil. The vineyard assay, designed to take into account the aggregative pattern of X. index distribution, revealed that marigold and hairy vetch are good candidates as cover crops to reduce X. index populations in vineyard. Moreover, this original experimental design could be applied to manage other soilborne pathogens.

Additional keywords: allelopathy, nematicidal plants, sampling design, Vitis vinifera.