OLIVE POMACE FOR CONTROL OF PLANT-PARASITIC NEMATODES

The efficacy of dry olive (Olea europaea) pomace as a soil amendment for control of root-knot nematodes was studied in a greenhouse experiment with 'Rutgers' tomato (Lycopersicon esculentum) on a sandy soil naturally infested with Meloidogyne arenaria. Olive pomace (OP) was added to the soil at rates of 0, 2, 4, 6, 10, 16, and 20 g/kg soil. OP was applied alone or in combination with 0.1 and 0.2 g urea/kg soil. Twelve days after addition of the amendments, tomato seedlings were transplanted to pots containing treated soil and were allowed to grow for 45 days. OP without urea was toxic to the seedlings and had no effect on root galling caused by M. arenaria. The OP + urea treatments resulted in increased size and weight of the seedlings. OP at 4-6 g/kg soil in combination with the 0.2 g rate of urea suppressed root galling and resulted in the heaviest and healthiest looking seedlings. In other studies, the nematicidal activity of OP distillates was assessed in the laboratory and greenhouse. Fresh OP dispersed in aqueous H2SO4 solutions was refluxed for 4 hr at 120 C. The concentration of acid in the OP-H2SO4 mixture was varied from 12.5-75% (v/v) of standard concentrated H2SO4 (sp. gravity = 1.84). The digests were distilled under vacuum (-1/3 bar). The distillates were tested in vitro for activity against Pratylenchus vulnus. All distillates were toxic to the nematode. When the distillate obtained from refluxing a mixture of OP with 12.5% H2SO4 was added to soil (5-20 ml distillate/kg soil) in a greenhouse experiment, it significantly reduced populations of M. arenaria and Heterodera glycines at dosages > 10 ml/kg soil. Results indicate that OP can serve as raw material for preparation of soil amendments with nematicidal properties.