Abstract
A diagrammatic scale with six levels (0.1-3.0; 3.1-6.0; 6.1-12.0; 12.1-18.0;18.1-30.0; 30.1-49.0%) was developed, compared, and evaluated along with two other scales to measure the severity of brown eye spots in coffee trees leaves. The scale was designed based on two others already in use in order to increase the efficiency of evaluation and for estimation values to approach as close as possible to their actual values. Two evaluations were performed using each of the three diagrammatic scales and one was performed without a diagrammatic scale, in seven day intervals. Using the proposed scale, the evaluators demonstrated better precision levels, accuracy, reproducibility, and repeatability in the estimations, when compared to the evaluators who did not use the diagrammatic scale, or who used existing scales. The proposed diagrammatic scale provided a reliable estimation to evaluate brown eye spot severity on coffee tree leaves.
Highlights
Brown eye spots, in which the etiological agent is the necrotrophic fungi Cercospora coffeicola Berkeley and Cooke, is found in the majority of coffee (Coffea arabica L.) growing regions of Brazil, causing injuries in the leaves and fruits (TALAMINI et al, 2003; SANTOS et al, 2008; PEREIRA et al, 2011)
The main objective of the present work was to elaborate upon, compare, and validate a diagrammatic scale to perfect the evaluation of the severity of brown eye spots in coffee tree leaves
The maximum value of severity of brown eye spots in coffee tree leaves observed in the field was 49.0%, due to the coalescence of lesions and the minimum of 0.2%
Summary
In which the etiological agent is the necrotrophic fungi Cercospora coffeicola Berkeley and Cooke, is found in the majority of coffee (Coffea arabica L.) growing regions of Brazil, causing injuries in the leaves and fruits (TALAMINI et al, 2003; SANTOS et al, 2008; PEREIRA et al, 2011). Coffee farms which are established in environments of extreme insolation can present greater disease severity, because the brown eye spot fungi type produces the cercosporina toxin, activated by light (DAUB et al, 2005). In response to the presence of brown eye spots on the leaves, the plant produces ethylene which can cause intense defoliation, creating quantitative losses, reducing the yield and productivity of the culture, even in reduced severity. Because of this it becomes extremely important to evaluate the intensity of the disease, with great accuracy and precision, even when it occurs in short intervals and with low amounts of severity
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