USE OF OZONATED WATER IN THE CONTROL OF VERTICILLIUM WILT ON EGGPLANT GROWN IN SOILLESS CULTURE.

Two experiments were carried out to assess if ozonated water used as a component of a soilless culture irrigation management plan can reduce the incidence of Verticillium wilt of eggplant caused by Verticillium dahliae Kleb. The assays were performed on eggplants grown in pots in a greenhouse either on vermiculite hydroponic culture or on sterilized compost. Plants were irrigated (twice daily) with ozonated water (at 5 mg/l) for the first 7 days after transplantation. Ozonated water was applied through an emitter inserted in the substrate so that it could reach directly the rhizosphere. The substrates were artificially inoculated with V. dahliae at concentration of 18 microsclerotia/g substrate. Non inoculated plants but treated with ozonated water and inoculated and non inoculated plants both untreated with ozonated water were used as controls. The severity of leaf wilting and vascular discoloration were assessed according to an empirical scale from 0 to 4. Some morphological parameters were also recorded. Plants grown in untreated vermiculite showed severity indices of leaf wilting and vascular discoloration of 3.1 and 2.8, respectively, whereas in untreated compost the severity indices of leaf wilting and vascular discoloration were 3.4 and 3.1, respectively. The application of ozonated water to vermiculite significantly reduced the severity of leaf wilting (65.7%) and vascular discoloration (72.6%). The reduction of severity of Verticillium wilt in compost was 45% for leaf wilting and 53% for vascular discoloration. The application of ozonated water had no effect on morphological parameters. [ABSTRACT FROM AUTHOR]