Diagrammatic scale to assess the severity of Alternaria on sweet granadilla leaves

Acosta-Trinidad L.T.; Acosta-Huaman G.C. · Revista Mexicana de Ciencias Agricolas (2026) · DOI: 10.29312/remexca.v17i3.4000

Resumen

Alternaria on sweet granadilla is a foliar disease caused by a saprophytic fungus that poses a significant threat as it reduces the photosynthetic area and consequently affects the quality of the fruit. Nevertheless, there is no instrument available to facilitate the estimation of leaf severity in the field. In view of this, the objective of this research was to design and validate a diagrammatic scale that allows assessing the severity of Alternaria sp. on sweet granadilla (Passiflora ligularis Juss.) leaves. A diagrammatic scale was developed based on an inspection of 124 leaves. The proposal included seven levels of foliar severity (0%, 1%, 2%, 4%, 8%, 16% and 28%), established according to the Weber-Fechner Law. For validation, ten evaluators recorded the severity on 60 leaves first without using the scale, and then seven days later, using it. The results projected an average coefficient of determination (R2) of 0.639 in the first evaluation and 0.88 when applying the proposed scale. In addition, absolute errors decreased. In conclusion, this tool proved to be accurate and reproducible for quantifying the severity of Alternaria sp. on sweet granadilla leaves.

Instituciones: Universidad Nacional Daniel Alcides Carrión