Nematicidal effects of olive pomace and green walnut husk on root-knot nematode Meloidogyne incognita on tomato

We studied the nematicidal effects of olive pomace (OP) and green walnut husk (GWH) on root-knot nematode (Meloidogyne incognita) in tomato. We determined under in-vitro conditions, the efficacy of OP and GWH extracts (0, 25, 50, 75 and 100%) against the second stage juvenile of M. incognita. Then, GWH and OP were mixed with sandy loam soil at rates of 0 %, 0.5 %, 1 %, 1.5 % and 2 % w/w under controlled atmosphere conditions. Tomato seedlings (Solanum lycopersicum L. cv Troy) were transplanted in pots and inoculated by second stage juveniles of M. incognita. Gall index (GI), egg mass index, root and shoot development of tomato plants were determined 60 days after inoculation. GWH (2 %) application reduced the GI of tomato seedlings by 85 % while OP (2 %) reduced it by 53 % than unamended control. Mortality rates of J2 were significantly affected by type of material, concentrations and the exposure time. GWH had higher juglone (5-hydroxy-1,4- naphthoquinone) concentration which suppressed the root knot nematodes as compared to OP. Higher rates of GWH and OP added into the soil resulted into healthy and much longer root systems. Plant fresh and dry weight increased in all treatments than control. Use of GWH and OP suppressed the root-knot nematodes without causing phytotoxicity to tomato plants.