Abstract
A set of standard area diagrams (SADs) was developed and validated to aid visual assessment of severity of frogeye leaf spot (FLS) caused by Cercospora sojina. The SAD has eight color images of diseased leaflets with severity values that ranged from 0.1 to 39.9 %. The SAD was validated by a group of 20 raters [10 experienced (ER) and 10 inexperienced (IR)], who assessed the same set of 50 images twice, the first without SADs and the second using SADs as an aid. The SADs significantly improved accuracy [coefficients of bias (C b ) were 0.64 and 0.99 for IR and 0.98 and 0.99 for ER, without and with SADs, respectively], precision [correlation coefficients (r) were 0.89 and 0.95 for IR and 0.94 and 0.97 for ER, without and with SADs, respectively] and overall agreement [Lin’s concordance correlation coefficients (ρ c ) were 0.57 and 0.94 for IR and 0.92 and 0.97 for ER without and with SADs, respectively]. The estimates of severity of FLS were more reliable when using SADs. Both the inter-rater reliability (coefficient of determination, R 2) and intra-class coefficient (ρ) were significantly increased by using SADs. Therefore, it is believed that the SADs proposed in the present study will be a useful tool to aid accurate, precise and reliable estimates of severity of FLS in experiments (e.g., fungicide screening, assessment of partial resistance of soybean genotypes to FLS) and to aid in decision-making purposes.
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Acknowledgments
Prof. F. A. Rodrigues thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for his fellowship. Mr. D. Debona and Mr. J. A. Rios were supported by CNPq and Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG), respectively. This study was supported by grants to Prof. F. A. Rodrigues from CAPES, CNPq and FAPEMIG.
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Debona, D., Nascimento, K.J.T., Rezende, D. et al. A set of standard area diagrams to assess severity of frogeye leaf spot on soybean. Eur J Plant Pathol 142, 603–614 (2015). https://doi.org/10.1007/s10658-015-0638-3
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DOI: https://doi.org/10.1007/s10658-015-0638-3