Suppressive effect of composted olive mill wastes soil amendments on the root-knot nematode Meloidogyne incognita

Incorporation into the soil of olive mill wastes after an appropriate composting process (composted - OMW) can represent a possible solution to the problem of their disposal and in addition can improve plant resistance to nematode attack by stimulating root development and plant growth because of their large content of nutritive elements. Therefore, a field experiment was undertaken in southern Italy to investigate the suppressive effect of incorporation into the soil of olive composted pomace, both fresh and exhausted, on the root-knot nematode Meloidogyne incognita. Composted olive pomace obtained by mixing fresh solid cake with farmyard manure and another compost obtained by mixing exhausted solid cake with poultry manure and wheat straw at doses of 10, 20 and 40 t ha-1 , were compared with two controls: i) untreated control; ii) treatment with fenamiphos (traditional nematicide) at 0.3 t ha-1 . All treatments were applied before transplanting tomato plants on a sandy soil infested by the nematode. Tomato crop yield, soil nematode population and root gall index were recorded in all plots. The results obtained showed that crop yield in amended plots was enhanced and that both composted - OMW were suppressive on M. incognita.