European Journal of Plant Pathology

, Volume 153, Issue 1, pp 273–277 | Cite as

A standard area diagram set for severity assessment of botrytis leaf blight of onion

  • Edivânio R. AraújoEmail author
  • Renata S. Resende
  • Carlos E. Krezanoski
  • Henrique S. S. Duarte


This work aimed to develop and validate a standard area diagram set (SADs) to estimate the severity of botrytis leaf blight of onion caused by Botrytis squamosa. For this purpose, a SADs with nine levels of severity (0.3; 1.0; 2.5; 5.0; 10; 20; 30; 40; and 57.7%) was developed from 193 symptomatic leaves collected in the field. The SADs was validated by 16 raters with no experience in evaluating plant diseases. Both precision and accuracy improved when they used the SADs. The statistical parameters for the 16 raters were: coefficient of bias - Cb (no SADs = 0.592, with SADs = 0.988); correlation coefficient – r (no SADs = 0.864, with SADs = 0.921); and Lin’s concordance correlation coefficient – ρc (no SADs = 0.513, with SADs = 0.909). In addition, estimates were more reliable: coefficient of determination - R2 (no SADs = 0.681, with SAD = 0.796); intra-class correlation coefficient - ρ (no SADs = 0.729, with SADs = 0.876). The SADs proposed here is a useful tool for improving visual assessments of severity of botrytis leaf blight of onion.


Allium cepa Botrytis squamosa Disease assessment Phytopathometry 



We would like to thank the field staff for their valuable contribution to this study. This work was funded by Epagri.

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• This manuscript has not been submitted to more than one journal for simultaneous consideration.

• This manuscript has not been published previously.

• This work is not split up into several parts to increase the quantity of submissions.

• No data have been fabricated or manipulated to support our conclusions.

• No data, text, or theories by others are presented as if they were the author’s own.

• Consent to submit has been received explicitly from all co-authors, as well as from the responsible authorities at the institute/organization where the work has been carried out.

• Authors whose names appear on the submission have contributed sufficiently to the scientific work and therefore share collective responsibility and accountability for the results.

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• There is no conflict of interest in the accomplishment and submission of this work.


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Copyright information

© Koninklijke Nederlandse Planteziektenkundige Vereniging 2018

Authors and Affiliations

  • Edivânio R. Araújo
    • 1
    Email author
  • Renata S. Resende
    • 1
  • Carlos E. Krezanoski
    • 2
  • Henrique S. S. Duarte
    • 2
  1. 1.Epagri/Estação Experimental de ItuporangaItuporangaBrazil
  2. 2.Departamento de Fitotecnia e FitossanitarismoUniversidade Federal do ParanáCuritibaBrazil

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