DIAGRAMMATIC SCALE OF SEVERITY FOR WHITE THREAD BLIGHT DISEASE IN YERBA MATE (Ilex paraguariensis SAINT HILAIRE)

VERESCHUK, MANUELA LIZZ; DOMINGUEZ, FACUNDO GABRIEL; ALVARENGA, ADRIANA ELIZABET; ZAPATA, PEDRO DARÍO

ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS.

ACAD BRASILEIRA DE CIENCIAS

Lugar: Rio de Janeiro; Año: 2022

0001-3765

The Yerba mate (Ilex paraguariensis St. Hil.) industry is one of the most important economic activities in Misiones, a province in the northeast of Argentina that is the world?s leading producer and exporter of this crop. White thread blight disease affects the cultivation of yerba mate reducing its quality and productivity. Due to the lack of a standardized visual method to quantify the severity of white thread blight (Ceratobasidium niltonzousanum) in yerba mate, a diagrammatic scale was developed and validated. Yerba mate branches were collected in a field in the north of Misiones province, and the actual severity was determined digitally. A six-level scale was developed using the DOSLOG program, based on the Weber-Fechner visual stimulus law. The validation was carried out by twenty evaluators. One evaluation without the diagrammatic scale and two evaluations with the scale were carried out in 14-day intervals. Accuracy, precision and reproducibility of the estimates were evaluated. Using the diagrammatic scale developed in this work, evaluators were able to improve the accuracy and precision of the estimates, and the repeatability of the scale improved by 94.74%. The scale was appropriate to assess the damage of white thread blight in yerba mate in Misiones province.