Host Suitability of Cut-Flowers to Meloidogyne spp. and Population Dynamics of M. hapla on the rootstock Rosa corymbifera ˈLaxa

The host suitability of cut-flowers to Meloidogyne spp. was tested under greenhouse conditions. In an experiment, the reaction of seven cut-flower species viz. Dianthus plumarius, Dianthus caryophyllus, Gypsophila paniculata, Limonium sinuatum (Fortress Dunkelblau), Limonium sinuatum (Petite Bouquet Mix), Rosa corymbifera ˈLaxaˈ and Freesia laxa against the root-knot nematode Meloidogyne hapla and M. incognita was evaluated. There were significant (P<0.001) differences in plant species as host for either M. hapla or M. incognita. Freesia laxa appeared to be a poor host for M. hapla and M. incognita with a reproductive factor of 0.5 and 1.1, respectively. Gypsophila paniculata and Rosa corymbifera were not suitable hosts for M. incognita resulting in a reproductive factor below one. On the other hand M. hapla reproduced significantly (P<0.05) higher on R. corymbifera ˈLaxaˈ than on the other plant species assessed. In all plant species, nematode infected plants were less vigorous than their uninfected controls. In the second test, the pathogenicity and population dynamics of M. hapla on the rootstock R. corymbiferaˈLaxaˈ were demonstrated. Within 24 hours after inoculation, about 2% of the juveniles had penetrated the root system. A week later, nematode penetration reached 14%. First eggs appeared 43 days after root infection. At final termination of the experiment 78 days after inoculation the reproduction factor of M. hapla was 58.9. In infected plants number of leaves per plant was lower than in the respective controls. In conclusion, the tested flower plants were hosts for M. hapla and M. incognita; however, the host status varied between plant and nematode species. R. corymbifera ˈLaxaˈ turned out to be a very good host for M. hapla allowing high nematode reproduction.