Effects of the root-knot nematodes Meloidogyne incognita and M. javanica on olive plants growth in glasshouse conditions

The influence of ten initial population levels (0, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 6.4, 12.8 and 25.6 second stage juveniles/cm3 soil) of Meloidogyne incognita and M. javanica on olive cultivar Zard growth was studied in two pot trials. Ten month old self-rooted olive cuttings were individually transplanted into 2 000 cm3 pot and inoculated with the defined initial populations, of both nematode species. Plants were grown in glasshouse for 13 months, then they were uprooted and plant growth (percent growth increase of main shoot length, number of nodes on main shoot, top and root fresh and dry weights and root length) and nematode parameters (root gall index, J2/g root, final nematode population density and reproduction rate Pf/Pi) were recorded. Results showed that cv. Zard was more susceptible to M. javanica than to M. incognita. A significant reduction of main shoot length growth 37.6 % and 10.7 % was observed at 0.1 and 12.8 juveniles/cm3 soil of M. javanica and M. incognita, respectively, in comparison to uninfested plants. Root systems of olive plants grown in M. incognita or M. javanica infested soils were galled within the gall index range 1.4–6. No significant differences were observed in the number of nodes on main shoot, top and root fresh weights and root dry weight at high levels of M. incognita Pi. A tolerance limit (T) of 0.4 juveniles/cm3 soil was estimated for olive plants cv. Zard to M. javania. The use of resistant olive rootstock or selected cultivars is recommended to minimize or to limit damage of nematode infections in nurseries and to prevent secondary attacks of soil borne plant pathogens especially Verticillium dahliae.