Biological control of the root-knot nematode Meloidogyne incognita by Paecilomyces lilacinus strain 251

The fungal biocontrol agent, Paecilomyces lilacinus strain 251 (PL251), was evaluated for its potential to control the root-knot nematode Meloidogyne incognita on tomato. In growth chamber experiments, a pre-planting soil treatment reduced root galling by 66%, number of egg masses by 74% and the final nematode population in the roots by 71% compared to the inoculated control. Significant dose–response relationships were established when conidia were applied to soil either with or without the glucose-based formulation. The effective concentration50 (EC50) values for the commercially formulated product ranged between 0.097 g and 0.08 g/500 cm3 soil, equivalent to an EC50 of 1.29 × 106 and 9.88 × 105 colony forming units (CFU)/g soil for the parameters gall index and final population per root, respectively. For the number of egg masses per root the EC50 was 0.007 g product or 2.64 × 105 CFU/g soil. Similarly, EC50 values for conidia applied without formulation were 0.068 g or 0.103 g/500 cm3 soil (EC50 of 8.10 × 105–1.40 × 106 CFU/g soil) for gall index and final population per root. In contrast, the EC50 was 0.096 g (EC50 of 1.28 × 106 CFU/g soil) for the number of egg masses per root. We demonstrated that a single pre-plant application at a concentration of 1 × 106 CFU/g soil is needed for sufficient biocontrol of M. incognita by PL251.