FULL RESEARCH PAPER Suitability of weed species prevailing in Spanish vineyards as hosts for root-knot nematodes P. Castillo & H. F. Rapoport & J. E. Palomares Rius & R. M. Jiménez Díaz Received: 12 March 2007 / Accepted: 19 July 2007 / Published online: 19 September 2007 # KNPV 2007 Abstract Commercial vineyards in southern Spain were surveyed and sampled during October to December 2004 to determine the extent to which common weeds present were suitable hosts of root-knot nematodes infesting soils of those vineyards. Seven weed species commonly growing in grapevine soils in southern Spain were found infected by either Meloidogyne incognita or M. javanica: Amaranthus retroflexus (redroot pigweed), Anchusa azurea (ox-tongue), Chenopodium album (goosefoot), Erodium moschatum (musk stork’ s bill), Malva rotundi- folia (low mallow), Sinapis alba (white mustard), and Solanum nigrum (black nightshade). The host suitability of the weeds to root-knot nematodes was evaluated on the basis of root galling severity and nematode popu- lation densities in soil and roots. Also, the host–parasite relationship in these naturally Meloidogyne-infected weeds was examined. All the weed species in the study were considered suitable hosts for M. incognita and M. javanica because: (a) high Meloidogyne spp. popula- tions occurred in roots and surrounding soil of the weed species; (b) the severity of root galling was high, and (c) well-established permanent feeding sites were observed in the histopathological studies of infected root tissues. In addition, this study presents the first reports of S. alba and A. azurea as hosts for M. incognita, and of E. moschatum as a new host for M. javanica, thus increasing the list of reported weed hosts for Meloido- gyne spp. These results indicate that noticeable popula- tion densities of M. incognita and M. javanica can be maintained or increased in these weeds, at population levels higher than those previously reported for the same nematodes infecting grapevine roots. The weeds infesting vineyards thus represent an important source of inoculum of Meloidogyne spp., and furthermore may act as reservoirs of these nematodes which can be disseminated within or among vineyards by agricultural operations. Keywords Alternative host . Grapevine . Histopathology . Host-parasite relationships . Meloidogyne incognita . Meloidogyne javanica . Nematode reproduction . Reservoir host Introduction Sedentary endoparasitic root-knot nematodes of the genus Meloidogyne are among nature’ s most successful Eur J Plant Pathol (2008) 120:43–51 DOI 10.1007/s10658-007-9195-8 P. Castillo (*) : H. F. Rapoport : J. E. P. Rius : R. M. J. Díaz Institute of Sustainable Agriculture, Spanish National Research Council (CSIC), Apdo. 4084, 14080 Córdoba, Spain e-mail: ag1cascp@uco.es R. M. J. Díaz College of Agriculture (ETSIAM), University of Córdoba (UCO), Edificio C4- “Celestino Mutis”, Carretera de Madrid Km 396, Campus de Rabanales, 14071 Córdoba, Spain