Elaboração e validação de escala diagramática para avaliação da severidade de oídio em folhas de mamoeiro

Abstract

A diagrammatic scale for powdery mildew (Streptopodium caricae) in papaya leaves was elaborated and validated in order to standardize the disease severity assessments. The proposed scale presented severity levels of 0.6, 1.2, 2.5, 5.0, 10.0 and 20.0%. Without the scale, all evaluators overestimated the disease severity. When the scale was used by the evaluators, better accuracy and precision levels were obtained, although there was a severity underestimation tendency, with absolute errors around 5% and many times inferior to this value and a few times above 10%. The evaluators presented good repeatability and high reproducibility of estimates when the scale was used. The diagrammatic scale was suitable for powdery mildew severity evaluation in papaya leaves.