Evaluation of the fungicides efficiency in garlic rust control

The Garlic rust (Puccinia porri) is a prevalent disease affecting all garlic-producing regions. Currently, its management relies on the application of fungicides. However, these applications are often performed without technical guidance, utilizing unregistered products and/or products with limited efficacy, leading to increased production costs and environmental pollution. The objective of this study was to assess the agronomic efficacy of fungicides in controlling garlic rust. The experiments were conducted at the Epagri-Estação Experimental de Caçador. In Experiment 1, the San Valentim cultivar was planted on July 5th and July 3rd for the 2023 and 2024 growing seasons, respectively. The experimental design consisted of randomized blocks with four replications, incorporating nine treatments, including a control treatment without fungicide application. In Experiment 2, the same cultivar was planted on July 5, 2022, following a randomized block design with four replications. The treatments involved the application of the fungicide mancozeb, with and without an adhesive spreader, in addition to a control treatment without fungicide application. The adhesive spreader Silwet was incorporated into the fungicide mixture at a concentration of 0.5 mL/L. Mancozeb was applied at a dose of 5 g/L. In both experiments, fungicide applications commenced 90 days after planting and were conducted at weekly intervals using a spray volume of 600 L/ha. Disease severity was evaluated weekly using a diagrammatic scale, and the data were subjected to statistical analysis using Tukey's test at a 5% probability level. The results demonstrated that the active ingredients tebuconazole, pyraclostrobin, mancozeb, metiram + pyraclostrobin, trifloxystrobin + tebuconazole, and cyproconazole exhibited superior efficacy in controlling garlic rust. Conversely, the active ingredients fluxapyroxad + pyraclostrobin, propiconazole, copper oxychloride, and mancozeb + copper oxychloride were less effective. Additionally, the application of mancozeb in combination with an adhesive spreader provided enhanced disease control compared to its application without the spreader. Regular assessments of fungicide efficacy are crucial to guiding producers in selecting the most effective strategies for crop protection and sustainable disease management.