Biological control of Verticillium wilt of olive within an integrated disease management framework

Abstract: Verticillium wilt of olive (VWO) is one of the most serious biotic threats for olivecultivation, the disease being a severe problem in some traditional olive-cultivating regionswithin the Mediterranean Basin. Control of VWO is difficult and none of the available controlmeasures is effective enough when applied individually. Therefore, an integrated diseasemanagement strategy is the only plausible framework for an effective control of VWO. The useof biological control agents (BCAs) can be considered either as a before-planting (preventive) oras a post-planting (palliative) action in established olive orchards. It is an approach that could beused in combination with other control tools. So far, only a few bacteria and fungi species havebeen examined as potential BCAs against VWO. Our studies have proved that some indigenousPseudomonas spp. strains of olive roots, some of them with an endophytic lifestyle, are effectiveagainst VWO caused by the highly-virulent, defoliating (D) pathotype. An interesting field to beexplored is the development of bioformulations which may combine BCAs with differentbiocontrol mechanisms operating synergistically; for instance, induction of systemic resistancetriggered by an endophyte and antibiosis by a root-surface colonizer. However, how biocontrolactions can be effectively implemented within this integrated framework still needs of in-depthstudies aimed to unravel the genetic and molecular basis underlying the olive/BCAs/V. dahliaetripartite interaction, as well as to understand how biotic factors may influence this system underfield conditions.