Control of white mold of dry bean and residual activity of fungicides applied by chemigation

• Published in: Crop protection 2017-04, Vol.94, p.192-202
• Main Authors: Miorini, Thomas J.J., Raetano, Carlos G., Everhart, Sydney E.
• Format: Article
• Language: English
• Subjects: Detached leaf bioassay; Fluazinam; Phaseolus vulgaris; Procymidone; Sclerotinia sclerotiorum
• ISSN: 0261-2194; 1873-6904
• DOI: 10.1016/j.cropro.2016.12.023

Sclerotinia sclerotiorum is a necrotrophic fungal pathogen that causes white mold of dry bean (Phaseolus vulgaris L.). Chemigation with fungicides is used for disease control, but effectiveness of this application method and impact of irrigation level on residual fungicide activity in the plant over time under field conditions has not been well characterized. To assess the best method of application and fungicide for disease control, we conducted field studies in three field sites in São Paulo State in Brazil. Contact fungicide, fluazinam, was applied via center pivot at three irrigation levels (2.5, 5.1, 10.1 mm) at the Itaí field site in 2013. Fluazinam and procymidone (systemic) were independently applied via sprinkler at three irrigation levels (3.0, 4.5, 6.0 mm) in 2013 and four irrigation levels (2.5, 5.0, 7.5, 10.0 mm) in 2014 at the Pereiras field site. Fungicides were also applied at the Pereiras site using a backpack sprayer in 2014. Three successive fungicide applications were made at Pereiras in 2013 and two successive applications made at Pereiras in 2014. Three leaves from each treatment of the four replicated plots were collected in 2-day intervals after application, and fungicide residues assessed using a detached leaf bioassay. Lesion areas were used to estimate percent disease control. Regardless of fungicide or application method, disease control decreased over time (ANCOVA; P