Abstract

Control of Botrytis cinerea Pers. leaf colonisation and bunch rot in grapes with oils was studied in laboratory and field tests. In detached lateral experiments, the essential oils from thyme (Thymus vulgaris L.) and clove (Syzygium aromaticum L.), as well as massoialactone (derived from the bark of the tree Cryptocarya massoia R.Br.) were not phytotoxic on leaves at concentrations of 0.33% or less. B. cinerea sporulation on artificially induced necrotic leaf lesions was significantly reduced by thyme (Thyme R) and massoialactone oils at 0.33%. A single application at veraison (1997/98) of either compound at concentrations of 0.33% controlled bunch rot and necrotic leaf lesion colonisation by B. cinerea compared with Botrytis control treatments. Spray applications of Thyme R oil (0.33%) at 8–10 day intervals (1998/99) from flowering to harvest controlled B. cinerea bunch rot but also caused floral tissues to senesce. Future research and potential applications of thyme oil are discussed.