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Field efficacy of fungicides to control downy mildew of onion

  • Edivânio R. AraújoEmail author
  • Renata S. Resende
  • Daniel P. Alves
  • Fábio S. Higashikawa
Article
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Abstract

Downy mildew is the main leaf disease of onion in southern Brazil. The management of the disease is carried out through frequent applications of fungicides. The objective of this study was to evaluate the fungicide efficiency in controlling downy mildew, under field conditions, during 2016–18 crop seasons. We evaluated the effect of weekly sprays of different active ingredients on the area under disease progress curve (AUDPC) and on commercial yield. There was variation among the best treatments in the three years of the test. However, we observed that sprays with metalaxyl-M (100 g/ha) + mancozeb (1600 g/ha) or mancozeb (1875 g/ha) were always allocated to the most productive groups: i) metalaxyl-M + mancozeb in the most productive group in 2016 (41.61 ton/ha), in the most productive group in 2017 (21.25 ton/ha), and in the second most productive group in 2018 (16.70 ton/ha); ii) mancozeb in the second most productive group in 2016 (32.62 ton/ha), in the most productive group in 2017 (19.88 ton/ha), and in the second most productive group in 2018 (16.00 ton/ha). The results demonstrated that metalaxyl-M and mancozeb are important molecules in the management of the disease. The use of fungicides composed only of molecules with systemic action is not recommended for the management of onion downy mildew under Brazilian conditions.

Keywords

Allium cepa L. Peronospora destructor Chemical control 

Notes

Acknowledgments

The authors would like to thank the field staff for their valuable contribution to this study. This research was funded by Epagri, and by funds from the Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq (process number 409509/2018-3).

Compliance with ethical standards

Ethical statement

The authors ensure that:

• 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.

• Authors are strongly advised to ensure the correct author group, corresponding author, and order of authors at submission.

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

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Copyright information

© Koninklijke Nederlandse Planteziektenkundige Vereniging 2019

Authors and Affiliations

  1. 1.Epagri - Estação Experimental de ItuporangaItuporangaBrazil

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