Evolution of Fungicide Resistant Pathogens in Grapes: <i>Erysiphe necator, Plasmopara viticola</i> , and <i>Botrytis cinerea</i>

<h3>Abstract</h3> <h3>Background and goals</h3> Powdery mildew (<i>Erysiphe necator</i>), downy mildew (<i>Plasmopara viticola</i>), and botrytis bunch rot (<i>Botrytis cinerea</i>) are among the most destructive diseases affecting grapevines worldwide. These diseases can severely impact both foliage and fruit, leading to substantial yield and quality losses. While cultural practices contribute to disease suppression, chemical control—particularly fungicides—remains the primary method for managing these diseases. Both multisite and site-specific fungicides are widely used, however, the intensive and repeated application of site-specific fungicides increases the risk of resistance development in pathogen populations. This review aims to provide a comprehensive overview of known fungicide resistance in <i>E. necator, P. viticola</i>, and <i>B. cinerea</i>, and to examine tools available for resistance monitoring. <h3>Methods and key findings</h3> We summarized findings from recent literature on the mechanisms and prevalence of fungicide resistance across major chemical classes used in viticulture. This review also evaluates diagnostic technologies ranging from traditional bioassays to emerging molecular tools which are currently used or have potential for detecting resistance in vineyard pathogens. Additionally, we highlight recent technological advances that could strengthen resistance monitoring and guide more sustainable fungicide use. <h3>Conclusions and significance</h3> Fungicide resistance poses a critical challenge to effective disease management in grape production. This review aims to provide a comprehensive analysis of the current state of known fungicide resistance in <i>E. necator, P. viticola</i>, and <i>B. cinerea</i>, and explores current and emerging diagnostic tools for monitoring fungicide resistance. Practical insights are also provided for researchers, extension personnel, and growers seeking to integrate resistance management into long-term disease control planning.