Evaluation of Pasteuria penetrans alone in combination with oxamyl, plant resistance and solarization for control of Meloidogyne spp. on vegetables grown in greenhouses in Crete

Abstract

In a plastic polytunnel in Crete, spores of Pasteuria penetrans (Pp) contained in powdered tomato roots were incorporated in 61 of soil at planting sites at a concentration of 25 000 spores g-1 of soil. The soil had been artificially infested with a natural population that was a mixture of Meloidogyne javanica and M. incognita. In one experiment the root galling and egg production on a nematode-susceptible tomato variety was significantly less in plots treated with Pp and oxamyl than in untreated controls. Pp and oxamyl had an additive effect in combined applications. Yields, however, did not differ significantly between treatments. There were reductions of nematode populations and root galling on a subsequent cucumber crop, which became severely damaged. This had to be curtailed because of premature senescence and death in the nematode-only control plots. The presence of Pp in 65–75% of mature females and on free-living juveniles in soil indicated that Pp had persisted in the soil and had increased over the two crops. The efficacy of the parasite was enhanced by oxamyl applications. In one experiment, nematodes failed to develop in a resistant tomato cv. and there was no beneficial effect from application of Pp and oxamyl. In a subsequent cucumber crop planted in the same plots, nematode population remained small in all treatments but 16–18% of mature females in Pp-treated plots were infected with the bacterium and 25–40% of J2 in the soil had spores attached to them. In another experiment when a solarization treatment was included, root galling, egg production and J2 in soil were significantly less after growing cucumber for 10 weeks in Pp, oxamyl and solarization treatments, In this case the efficacy of Pp was enhanced after oxamyl application and probably in solarized soil; when all factors were combined the treatments were additive