Deciphering the Distribution Patterns of Pathogens Associated With Esca and Petri Diseases in Rootstock Mother Vines Potentiates the Development of Alternative Control Strategies in Grapevine Nurseries

The widespread emergence of Phaeomoniella chlamydospora and Phaeoacremonium minimum in grapevine nurseries over the past two decades has raised concerns about the future sustainability of the viticulture sector. Managing these pathogens is challenging due to the lack of chemicals and the limited effectiveness of biocontrol agents. This study aimed to identify cultivation practices in nurseries to mitigate infection risks in propagation material. By coupling nested PCR with quantitative PCR, pathogen distribution and concentration of prevailing P. chlamydospora along the length of rootstock canes were investigated. Detection frequency of both pathogens decreased from the basal end to tip sections. Therefore, using tip sections highlights the potential of producing pathogen‐free propagation material and retaining healthier rootstock mother fields. P. chlamydospora biomass was reduced by 92.5% from the base to the tip in canes harvested in 2020, and by 100% in 2021. Furthermore, the occurrence of both pathogens and the biomass of P. chlamydospora were found to be overall lower in the rootstock mother field after the elimination of esca‐affected vines. The incidence of P. chlamydospora at the basal end was reduced by 90.6% (2020–2022), while of P. minimum by 23.0%. Likewise, P. chlamydospora biomass was reduced (2020–2021), ranging from 98.5% at the base to 100% at the tip. These findings emphasise targeted harvesting, tip utilisation, and elimination of esca‐affected mother vines as effective strategies for minimising pathogen infections in grapevine nurseries. Integrating these cultivation practices into the existing Petri disease management protocols could enhance the production of high‐quality propagation material.