Screening water extracts and essential oils from Mediterranean plants against Verticillium dahliae in olive

Verticillium wilt in olive is considered the most serious biotic threat to this crop. Effective control of this disease relies on an integrated disease management strategy in which the biological control has an important role nowadays. This work describes the potential effect of 44 plant extracts and 20 essential oils against Verticillium dahliae. The results demonstrate the in vitro and in planta effectiveness of essential oil from Thymus, in particular Thymus sp. 04 (prepared in the laboratory), and the commercial product Thymus sp. 01, against Verticillium dahliae. The inhibition of mycelial growth and microsclerotia reached 100% in both treatments and achieved a disease reduction in olive plants by 65% and 42% for Thymus sp. 04 and sp. 01, respectively. These treatments showed the potential for essential oils use in the control of this pathogen in the frame of an integrated disease management strategy. This is the first report of the use of essential oils to control Verticillium wilt in olive plants. Further studies are warranted to identify the bioactive compounds in the essential oil that control V. dahliae and evaluate their potential use as natural fungicides.