Evaluación y validación de un diagrama de área estándar (SAD) de severidad para la cuantificación de mildiu velloso Peronospora sparsa Berkeley de la rosa Rosa sp

Abstract

The project addressed the need for a standardized tool to objectively quantify the severity of downy mildew caused by Peronospora sparsa in rose crops. The objective was to develop and validate a Standard Area Diagram (SAD), under the hypothesis that its use improves the precision, accuracy, and concordance of visual assessments performed by evaluators with different levels of experience. Symptomatic leaves were collected from a commercial greenhouse, digitally scanned at high resolution, and the percentage of foliar damage was quantified using Assess 2.0 software. Based on these values, minimum and maximum severity levels were determined, and seven categories with linear increments were generated. The results showed that the use of the SAD significantly reduced estimation errors and enhanced the parameters of precision, accuracy, and concordance in both experienced and inexperienced evaluators. It is concluded that the developed diagram constitutes a valid and reliable tool for evaluating this disease in roses. Keywords: quantification, standard area diagram, severity, phytopathometry, ornamentals.