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 concentration(50) (EC50) values for the commercially formulated product ranged between 0.097 g and 0.08 g/500 cm(3) soil, equivalent to an EC50 of 1.29 x 10(6) and 9.88 x 10(5) 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 x 10(5) CFU/g soil. Similarly, EC50 values for conidia applied without formulation were 0.068 g or 0.103 g/500 cm(3) soil (EC50 of 8.10 x 10(5)-1.40 x 10(6) CFU/g soil) for gall index and final population per root. In contrast, the EC50 was 0.096 g (EC50 of 1.28 x 10(6) CFU/g soil) for the number of egg masses per root. We demonstrated that a single pre-plant application at a concentration of 1 x 10(6) CFU/g soil is needed for sufficient biocontrol of M. incognita by PL251. (c) 2005 Elsevier Inc. All rights reserved.