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Verticillium dahliae is one of the most devastating soilborne pathogens for horticulture production. The pathogen has a broad host range and currently there is no effective chemical disease management, therefore, novel sustainable integrated disease management strategies should be considered. In this respect, we questioned whether the soil application of common microbiological growth media can influence the plant—microbe interactions and, subsequently, offer protection against V. dahliae. Indeed, the addition of Nutrient Broth (NB) and Potato Dextrose (PD) in non-sterilized soil reduced Verticillium wilt symptoms in eggplants. The addition of NB in sterilized soil did not reduce the disease symptoms compared to controls, however the addition of PD enhanced plant protection against V. dahliae. Following the results of a split root bioassay in eggplants, the possibility that NB and PD triggered the plant defense mechanisms against V. dahliae was excluded, since NB and PD did not reduce wilt symptom. Therefore, PD may be used as an easy food source for V. dahliae, detouring the pathogen from the root system of plants, while NB may affect the soil microbiome by enhancing antagonism in rhizosphere, or antagonistic interaction between V. dahliae and rhizospheric microbiome. Subsequently, several bacterial strains were isolated from the NB-treated rhizosphere and examined for their biocontrol activity against V. dahliae. Among the examined strains, a Pseudomonas putida strain, Z13, significantly reduced Veticillium severity and incidence under greenhouse conditions. [ABSTRACT FROM AUTHOR]

In the last two decades grapevine trunk diseases (GTDs) have emerged as the most significant threat for grapevine sustainability worldwide. The tracheomycotic fungus Phaeomoniella chlamydospora (Pch) is the predominant GTD-associated species and cannot be controlled with available chemicals. In the present study, we evaluated the effectiveness of two microbial strains (Paenibacillus alvei K165 and Fusarium oxysporum F2) against Pch in grapevine. In vitro bioassays, performed in a growth culture medium simulating the xylem environment, indicated that F2 decreased Pch growth and sporulation, whereas K165 did not have any effect on Pch growth. In planta experiments revealed that root-drench and stem-puncture application of K165 and F2 reduced the endophytic relative DNA amount of Pch by 90% and 82%, respectively, compared to controls. However, wood discoloration, the typical symptom of Pch infection, was not reduced in the F2 treated grapevines. Nevertheless, the F2 treated grapevines harbored higher lignin levels compared to mocks, as it was also done by K165. Therefore, F2 and K165 have the potential to be used as biocontrol agents against Pch in grapevines. [ABSTRACT FROM AUTHOR]