Impact of three different fungicides on fungal epi- and endophytic communities of common bean (Phaseolus vulgaris) and broad bean (Vicia faba)

ABSTRACT

In this study, the impacts of three different fungicides to fungal phyllosphere communities on broad bean (Vicia faba, Fabaceae) and common bean (Phaseolus vulgaris, Fabaceae) were analyzed. The fungicides included copper, sulfur, and azoxystrobin. The plants were sowed, grown, and treated under conditions occurring in conventional and organic farming. A culture-based approach was used to identify changes in the phyllosphere fungal community after the treatment. Different effects on species richness and growth index of the epiphytic and endophytic communities for common bean and broad bean could be shown. Treatments with sulfur showed the weakest effect, followed by those based on copper and the systemic azoxystrobin, which showed the strongest effect especially on endophytic communities. The epiphytic fungal community took five weeks to recover after treatment with azoxystrobin. However, the effect of azoxystrobin on the endophytic community lasted more than five weeks. Finally, the data suggest that the surface structure of the host leaves have a huge impact on the mode of action that the fungicides exert.

KEYWORDS:

• Endophytes
• epiphytes
• fungicides
• azoxystrobin
• sulfur
• copper

Acknowledgments

We thank Oliver Röhl, Hai Nguyen and Alistair McTaggart for critically reading the article and improvement of language. The Botanical Garden of the Ruhr-Universität Bochum, Germany kindly provided facilities for the field experiment and supported the project continuously.

Funding

We thank the Deutsche Bundesstiftung Umwelt for financial support.