Abstract
<jats:p>Grapevine trunk diseases (GTDs) are major contributors to vineyard productivity decline, causing progressive vine deterioration and yield loss. Existing research highlights the need for effective alternative protection methods due to the limitations of conventional chemical treatments. Hydrogen peroxide (H₂O₂) has been identified as a potential treatment because of its antimicrobial properties; however, studies on its use in grapevine protection are still limited. This study aimed to evaluate the effectiveness of H₂O₂ application on symptomatic grapevines in reducing GTD symptoms and its impact on yield and qualitative must parameters. The experiment was conducted during the 2021 growing season on the grapevine cultivars Malvazija istarska and Cabernet Sauvignon. H₂O₂ (10%) at a dose 5 ml was injected into the vines, and treatment efficacy was assessed through a visual evaluation of vine health, as well as analyses of yield, sugar content, pH, and titratable acidity of grape must. Results showed that H₂O₂ application reduced GTD symptoms and promoted vine recovery, particularly when applied at early disease stages. While the treatment significantly improved yield in recovered vines of Malvazija istarska, no significant negative changes were observed in sugar content, pH, or titratable acidity of the must. The treatment has not affected differences in yield of Cabernet Sauvignon, sugar content, pH, or total acidity of the must. Further research is required to optimize treatment conditions and elucidate the mechanisms of H₂O₂ action in grapevine disease management.</jats:p>