Biological Control Agents in the Management of Different Initial Population Densities of Meloidogyne javanica in Tomato

The efficacy of single and combined application of Trichoderma harzianum and Pseudomonas fluorescens (CHA0) in the controlling of Meloidogyne javanica on tomato plants was evaluated under green house conditions. Seeds of the susceptible tomato cv. Early-Urbana were sown in clean plastic pots containing 1.5 kg steam sterilized soil. Four weeks after planting, the soil of each pot was infested with a suspension of 20 ml/kg soil of T. harzianum (106 spores/ ml) and a suspension of 15 ml/kg soil of P. fluorescens (CHA0) (108 CFU/ ml). Soil of other pots were infested with the two tested bio-agents together as a combined application. Seven days later, plants in all pots, except the controls, were inoculated with M. javanica at initial population densities of 1, 2 or 4 eggs/ cm3 soil. Sixty days after nematode inoculation, the parameters of plant growth and nematode reproduction were determined. Results showed that the nematode reproduction factor (Rf) on the plants infected with 1, 2 and 4 eggs/ cm3 decreased by 58, 63 and 31% after the single application of T. harzianum, 11, 33 and 12% after the single application of P. fluorescens (CHA0) and 43, 55 and 49% after the combined application of the bio-agents, respectively. Combined application of the two bio-agents was found to be the most effective in controlling the higher initial population density of the nematode (4 eggs/ cm3).