BACKGROUND: Sclerotium rolfsii is a soil-borne phytopathogenic fungus that causes diseases in economically important crops. Eradication of the fungus is hampered by its wide range of hosts, as well as its capacity to form sclerotia. Recently, we have shown that the endophytic fungus Daldinia cf. concentrica emits biologically active volatile organic compounds (VOCs); we also demonstrated that one VOC, trans-2-octenal, was the most effective against various phytopathogenic fungi. Thus, the aim of this study was to examine the potential of this compound to control hyphae and sclerotia of S. rolfsii, both in vitro and in soil. RESULTS: We found that in vitro exposure of S. rolfsii mycelium to trans-2-octenal in air fully inhibits and kills the fungus. Elimination of sclerotia viability occurred at the same concentration, but direct contact between the sclerotia and the compound was needed. trans-2-Octenal also affected the viability of both hyphae and sclerotia of S. rolfsii in small pots containing loam soil. CONCLUSION: We suggest the use of trans-2-octenal as a novel compound to control S. rolfsii.