Objective The objective was to investigate the inhibition effect of bio-active organic fertilizer "Hongtu-Yun" on tomato root-knot nematode disease.

Method The laboratory experiment was conducted to determine the leachates of bio-active organic fertilizer "Hongtu-Yun" with different concentrations on eggs hatch of root knot nematodes and lethal effect on 2 instar(J2)larvae, and the inhibition effect of"Hongtu-Yun"on tomato plant growth and root knot nematode disease were observed by pot experiments with different way of fertilization.

Result After being treated by leachates with concentrations of 120, 160 and 200 g/L for 36 h, the mortality of J2 larvae was 62.6%, 79.6% and 84.5%, respectively. And after being treated under the same condition for 7 h, the hatching rates of eggs were 6.00%, 2.66% and 2.67%, respectively. Both the mortality and the hatching rate of all treatment groups showed significant differences in comparison with distilled water control group.Pot experiments indicated that "Hongtu-Yun" could significantly suppressed root-knot nematode disease. The relative control efficiency of 80 g "Hongtu-Yun" used as base fertilizer was 80.3%, which had no significant difference with that of abamectin treatment. The relative control efficiencies of other two treatments(surface broadcasting of 80 g "Hongtu-Yun", and surface broadcasting of 40 g "Hongtu-Yun" with 40 g "Hongtu-Yun" used as base fertilizer)were 56.6% and 47.4%, with significant decreased root-knot index. Moreover, the application of "Hongtu-Yun" promoted the growth of tomatoes including the plant height, the stem diameter, and the aboveground part biomass and decreased the necrosis rate of roots.

Conclusion The bio-active organic fertilizer"Hongtu-Yun"has a good control effect on tomato root-knot nematodes, which can provide a theoretical basis for the promotion of"Hongtu-Yun"and the safe and high-quality production of tomatoes.