Sustainable management strategies for root-knot nematodes (Meloidogyne spp.)
The work presented in this thesis evaluated the potential of integrated management of root-knot nematodes. Emphasis was given to the use of two complementary biological control agents, Paecilomyces lilacinus and Bacillus firmus, together with appropriate cultural practices including soil solarization and organic soil amendments, in comparison with the judicious use of chemical control. Use of soil amendments for nematode population suppression, demonstrated that application of fresh-chopped grass and brassicacaeous amendments suppressed root-knot nematode populations. After incubation of soil for 2 weeks in plastic covered pots, the addition of broccoli, cauliflower and cabbage at 10 kg/m2 reduced the number of females in roots by 69, 45 and 39.5% respectively. Volatiles from grass, broccoli and Vapam reduced the number of females in roots by 32, 40.5 and 100% respectively, in plastic covered pots after incubation of amended soil for 1 week. In field experiments, at the end of the cropping season, significantly more nematodes parasitized the roots in control plots compared with those treated with B. firmus with and without soil solarization. Soil solarization alone or in combination with P. lilacinus provided efficient control of root-knot nematodes in comparison with the untreated control. No significant additive of synergistic interactions occurred between soil solarization and P. lilacinus. Attempts to enhance soil suppressiveness to root-knot nematodes through inundative applications of different inoculum densities of P. lilacinus and B. firmus, singly or together, were successful. There is some evidence that time may be an important factor in determining the activity of these biocontrol agents.