Validation of a generic model for predicting garlic rust

Garlic rust (Puccinia porri) occurs in all producing regions. Currently, the control of fungal diseases is being done through the use of fungicides. Frequently, these products are applied without proper technical considerations, using unapproved or inefficient products for disease control, increasing production costs and environmental pollution. The objective of this work was to validate the generic disease model for predicting garlic rust. The work was carried out at the Experimental Station of Caçador – Epagri, during the agricultural years 2019, 2020 and 2021. In the three years, the cultivars Gigante (early garlic cultivar) and San Valentim (late garlic cultivar) were used. The rust occurred naturally in the field. Rust severity was evaluated weekly until disease progress stabilized. The “generic disease model” was used to predict garlic rust. The validation of this model was given from the graphic comparison between the observed values of rust severity in the field and simulated data by model. It was observed that in the year 2019, for both cultivars, the disease intensity was higher in relation to the seasons of 2020 and 2021. However, the generic model correctly simulated the beginning of the rust epidemic in the garlic crop in the three years studied, and may assist the producer in deciding the ideal time to start disease management.