Impact of sown fallows on the Xiphinema index populations in different soil types

Abstract

The nematode Xiphinema index is, economically, the major virus vector in viticulture, transmitting specifically the Grapevine Fanleaf Virus (GFLV), the most severe grapevine virus disease worldwide. The management of this disease has long been to use soil fumigation, harmful for both the applicator and the environment. The objective of this study was to evaluate an alternative approach using plants to reduce vector nematode populations between uprooting and replanting. Of thirty botanical species, tested in previous greenhouse trials, the seven best performing plants were evaluated for their capacity to reduce X. index populations in soil compared to bare soil in 5 field trials on different soil types in Bordeaux and Burgundy. In most trials, sown fallows reduced the number of X. index nematodes more efficiently than bare soil. All plants tested in field, except Trifolium pratense, showed their efficacy in field on survival of nematodes X. index but this efficiency varied according to species and site. The best results were obtained with Medicago hybride, Tagetes minuta, Avena sativa and Vicia villosa. Over the following years we will be evaluating if a decrease of the populations of the nematode vector does lead to a significant drop or delay of GFLV contamination for the newly planted vines.