Nematology , 2004, Vol. 6(1), 125-128 Host suitability of some crucifers for root-knot nematodes in southern Spain Gracia L IÉBANAS 1 and Pablo CASTILLO 2; 1 Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Campus ‘Las Lagunillas’s/n, Edicio B3, 23071-Jaén, Spain 2 Instituto de Agricultura Sostenible, Consejo Superior de InvestigacionesCientícas (CSIC), Apdo. 4084, 14080-Córdoba,Spain Received: 4 September 2003; revised: 14 November 2003 Accepted for publication:14 November 2003 Summary – Six crucifer species as potential cover crops, Ethiopian mustard (Brassica carinata line C-101), turnip (Brassica rapa cv. Norfolk), radish (Raphanus sativus ), wild rocket (Eruca vesicaria ), wild cabbage (Moricandia moricandioides ) and white mustard (Sinapis alba), were tested for susceptibility to Meloidogyne arenaria race 2, M. incognita race 1 and M. javanica . Experiments were conducted under glasshouse conditions at 22-28 C for 2 months after inoculation of plants with eggs and second-stage juveniles. All crucifers were infected by Meloidogyne spp. The nematode and crucifer species signicantly inuenced the severity of root galling and nematode reproduction. Among the plants tested, turnip was the most suitable host for all three Meloidogyne spp. as indicated by severity of root galling and nematode reproduction. The least suitable hosts were wild rocket for M. arenaria , radish for M. incognita and white mustard for M. javanica . The reproductiontness of M. javanica was greater than that of M. arenaria race 2 and M. incognita race 1 on all plants. Keywords – Brassica carinata , B. rapa, Eruca vesicaria , Meloidogyne arenaria , M. incognita , M. javanica , Moricandia morican- dioides , Raphanus sativus , Sinapis alba. Over the last decade, signicant research efforts have been devoted in Andalusia (southern Spain) to the use of cover crops in olive orchards (Castro, 1993; Garcia Torres, 2001). The use of a permanent orchard oor vegetation is the most common orchard soil management system used (Hogue & Neilsen, 1987). Some of the potential benets of such cover in olive orchards in Andalusia include reduced soil erosion, improved soil structure and fertility, increased water inltration, and reduced surface run-off and weeds (Castro, 1993; Pelegrín et al., 2001). Several plant species are being tested in Andalusia, among which some crucifer species are of great interest. However, cruciferous cover crops may be hosts for plant- parasitic nematodes, such as Meloidogyne spp. (Gardner & Caswell-Chen, 1994; McSorley & Frederick, 1995). Therefore, since crucifers are being includedas cover crop systems in olive orchards in Andalusia, their host status to Corresponding author, e-mail: ag1cascp@uco.es the major root-knot nematodes infesting this region must be determined. The suitability of a host for plant-parasitic nematodes is expressed as the ability of the nematode to multiply on the plant. Host suitability may be expressed objectively as the ratio of the number of nematode units recovered at the end of the test, the nal nematode population density (Pf ), to the number of nematode units used to inoculate the plant,the initial populationdensity (Pi) (Lewis, 1987). For root-knot nematodes, host suitability can be assessed by measuring the severity of root galling and reproduction on plants after articial inoculations (Hussey, 1985). The objective of this study was to determine the host suitability of some cultivated and wild crucifers, with potential use as cover crops in Andalusian olive orchards, to the three common root-knot nematodes M. arenaria, M. incognita and M. javanica. © Koninklijke Brill NV, Leiden, 2004 125 Also available online - www.brill.nl