Reduced introduction of Verticillium dahliae through irrigation systems and accumulation in soil by injection of peroxygen‐based disinfectants

Controlling Verticillium dahliae through irrigation systems should be an important measure within integrated management of verticillium wilt of olive in Spain. Pathogen content of water infested by V. dahliae conidia and sclerotia can be diminished following in vitro treatments with the disinfectants OX‐VIRIN and OX‐AGUA AL25. Three concentrations per disinfectant were assessed for their effectiveness under operational conditions of modern irrigated olive orchards. Sterilized potted soil was drip‐irrigated with conidia‐ or sclerotia‐containing water that was pumped from a storage tank and disinfected (or not, control) within the pipelines via metering pumps. The trial was carried out in autumn and spring for each type of propagule infesting the water. The inoculum dispensed through drippers and the total inoculum density accumulated in soil were estimated. Furthermore, the treated residual inoculum in soil was assessed for pathogenicity on olive plants. Conidial incorporation in soil was prevented by most disinfectant treatments in spring; while for sclerotia, prevention was observed only at the highest OX‐VIRIN (51.2 mL L−1; in both seasons) and OX‐AGUA AL25 (11.27 mL L−1; in autumn) concentration. The remaining disinfectant treatments reduced conidia and sclerotia accumulation in soil by over 99% and 95%, respectively. Season particularly impacted the efficacy of lower concentrations. Expression of symptoms was not observed in olive plants grown in previously treated soils. The infectivity of the residual inoculum present in some treated soils was prevented, markedly reduced or limited to the roots. These results provide a novel, interesting and feasible approach in the management of the disease.