Control of diffuse abaxial apple scab by the systemic fungitoxicity of fluopyram and the defense enhancement of fosetyl‑Al

De Maeyer, Luk (author), Švara, Anže (author), van Hemelrijck, Wendy (author), Hilz, E. (author), Da Silva, M. (author), Steppe, K. (author), Verbeke, Sarah (author), Abts, Willem (author), Meredith, R. (author), Mikulič Petkovšek, Maja (author), Veberič, Robert (author), Claes, M. (author), De Storme, Nico (author), Arnold, C. (author)

Diffuse scab symptoms (Venturia inaequalis) on the abaxial leaf surfaces of apple trees (Malus×domestica Borkh.) coincide with increased infection pressure in apple orchards. The epidemiology of diffuse abaxial scab has been linked to both quiescent primary and secondary infections that proliferate in the summer. These symptoms are often overlooked and initially appear on cluster leaves and later spread intermittently along the shoot from basal toward apical leaves approximately 7–8 weeks after leaf unfurling. In this study, we investigated the effect of Luna® Care® (FLU&FEA), a fungicide containing fluopyram (FLU) and fosetyl-Al (FEA), on scab development under field conditions. FLU&FEA treatments positioned in the post-flowering period were most effective against diffuse abaxial scab and were associated with the combination of direct effects against the fungal pathogen and plant defense enhancement by fluopyram and fosetyl-Al, respectively. FLU&FEA reduced both the incidence and severity of diffuse abaxial scab symptoms up to 11 weeks after the last application and suppressed V. inaequalis DNA content in treated and newly formed unsprayed leaves as a result of acropetal systemic activity of the fungicide element combined with inducing the plant defences. A season-long upregulation of genes involved in leaf ontogenic resistance and biosynthesis of phenolic compounds was correlated with the FLU&FEA treatment, which also limited ascospore release from abscised overwintering leaves in the following season. As such, FLU&FEA constitutes a novel tool for sustainable and efficient scab control that inhibits diffuse abaxial scab and reduces infection pressure in the following season.

• Language: English
• Keywords: Malus × domestica, Venturia inaequalis control, epidemiology, leaf aging, ontogenic resistance, FLU&FEA
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 16 str.
• Numbering: Vol. 132, iss. 132, art. 43
• PID: 20.500.12556/RUL-171332
• UDC: 632.937
• ISSN on article: 1861-3837
• DOI: 10.1007/s41348-025-01113-1
• COBISS.SI-ID: 246098947
• Publication date in RUL: 22.08.2025

Record is a part of a journal

• Title: Journal of plant diseases and protection
• Shortened title: J. plant dis. prot.
• Publisher: Ulmer
• ISSN: 1861-3837
• COBISS.SI-ID: 522334489

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: jablana, škrlup, bolezni rastlin, varstvo rastlin, fungicidi