Volatiles from biofumigant plants have a direct effect on carpogenic germination of sclerotia and mycelial growth of Sclerotinia sclerotiorum

Abstract

Aims Sclerotia of Sclerotinia sclerotiorum survive in soil and germinate to produce apothecia which release airborne ascospores. Current control methods rely predominantly on the use of fungicides to kill ascospores. The aim of this research was to identify potential biofumigation treatments which suppress sclerotial germination, providing a potential alternative and long-term approach to disease management. Methods Microcosm and in vitro experiments were conducted using dried and milled plant material from six different biofumigant crop plants to determine effects on carpogenic germination of sclerotia and mycelial growth of S. sclerotiorum. Results All biofumigant plants significantly reduced germination of S. sclerotiorum sclerotia in the microcosm experiments, but were less effective against larger sclerotia. In vitro experiments showed a direct effect of biofumigant volatiles on both the mycelial growth of S. sclerotiorum, and carpogenic germination of sclerotia, where the most effective treatment was B. juncea ‘Vittasso’. Conclusions It was clear from this study that biofumigant crop plants have potential as part of an integrated disease management system for control of S. sclerotiorum. The microcosm experiments described here provide a straightforward and reliable screening method for evaluating different biofumigants for activity.