Optimum substrate and carrier for Purpureocillium lilacinum and its effectiveness against Meloidogyne javanica on tomato

The soil-borne root-knot nematode (Meloidogyne javanica) causes heavy losses in tomato plants every year. Their management by chemical nematicides is difficult, expensive, and may also kill soil beneficial microorganisms, so other safer methods should be used to replace them. Purpureocillium lilacinum is an important biological control agent against root-knot and cyst nematodes. This study was carried out to determine the appropriate substrate and carrier of this fungus and its effect on these nematodes in tomatoes.

P. lilacinum was propagated in vitro on seeds of millet, corn, alfalfa, and clover substrates and their spore production was assessed 10, 20, and 30 days after inoculation. The survival of the fungal spores was then examined in talc, kaolin, and corn cob powder as carriers for 12 months. The effect of the fungus in the mentioned carriers against Meloidogyne javanica on tomato was investigated in the greenhouse by means of a completely randomized design experiment.

The highest number of spores in one gram of substrate was produced on millet seed on day 30. The highest number of survived spores was detected in the corncob powder carrier at all 12 months of the experiment. The fungus on corn cob powder was able to control M. javanica to 95% was similar to the nematicide Flopyram. This formulation also had a superior effect in establishing the fungus in the rhizosphere and on roots, suppressing the growth parameters of nematode and increasing plant growth.

The fungus reproduced well on millet seeds and could last longer if formulated on corn cobs powder. Therefore, corn cobs powder can be a suitable base to produce an effective powdered product against M. javanica.