Ozonated water electrolytically generated by diamond-coated electrodes controlled phytonematodes in replanted soil
Phytonematodes cause severe yield losses in horticulture, partly because they are difficult to manage. Compact, energy-efficient generators that electrochemically produce ozonated water by utilizing diamond-coated electrodes have become available. In this study, the application of on-site generated ozonated water to inactivate soil nematodes and to mitigate nematode-mediated apple replant disease was tested. Pratylenchus penetrans was highly susceptible to dissolved ozone (LC50 0.6 mg L-¹). In one greenhouse experiment, treatment of P. penetrans in soil with ozonated water (0.27 mg ozone L-¹ soil) reduced subsequent invasion of the nematodes into roots by 60%. Growth of apple saplings in soil that was affected by apple replant disease (ARD) was significantly improved following a treatment with 1/10 volume ozonated water compared to the control. In a second greenhouse experiment, one-time drenching of ARD soil with ozonated water was followed by improved growth of apple plants similar to that in autoclaved soil. A second application of ozonated water did not further improve plant growth. The number of active nematodes in replanted soil that moved through a Baermann filter was significantly reduced by all tested concentrations of ozone (0.12-0.75 mg L-¹ soil). A fraction of 19-36% of the nematodes survived and slightly recovered after four weeks. In conclusion, on-site generated ozonated water has potential to mitigate nematode problems in horticulture and to expand management options.
Institute for Epidemiology and Pathogen Diagnostics, Federal Research Centre for Cultivated Plants, Julius KühnInstitute (JKI)
Institute for Epidemiology and Pathogen Diagnostics, Federal Research Centre for Cultivated Plants, Julius KühnInstitute (JKI) ; Faculty of Agriculture, Benha University