Comparación de métodos para cuantificar severidad de la roya del cafeto en diferentes tamaños de hojas

Abstract

Coffee rust is the most important disease of the crop, the severity of leaf damage caused by the pathogen causes leaf abscission and significantly affects the reduction of yields. This investigation was carried out with the objective of comparing the visual method with a digital one, in the quantification of the percentage of severity of the rust in different sizes of leaves. The quantifications of the disease were carried out at the University Clinic for Agricultural Diagnostics at Oriente University. To carry out the experiment, 360 leaves injured with rust were collected from Catuaí Rojo plantations and divided into three groups, categorized according to leaf area into large, medium and small, each group was represented by 120 leaves, initially evaluated by the visual method by two observers with the help of the diagrammatic scale and later with the digital method by analyzing images with the ImageJ® program. The randomized block design was used with a 2x3 factorial arrangement with ten repetitions per experimental unit. The data were processed by analysis of variance. It was found that the severity percentage did not present statistical differences for the digital methodology when the size of the sheets was changed; while, for the visual methodology, therewas an influence of the size of the leaves, observing that the estimated severity increased as the size of the leaves decreased. The digital method is a reliable alternative for the quantification of the severity of attack by coffee rust.