Control of postharvest fungal rots in grapes through the use of Baccharis trimera and Baccharis dracunculifolia essential oils

Postharvest diseases cause considerable losses during transportation and storage. Synthetic fungicides are primarily used to control postharvest disease loss, however the development of new and alternative agrochemicals is necessary. In this study, the effect of Baccharis trimera and Baccharis dracunculifolia essential oils (EOs) to control of postharvest fungal rots in grapes was evaluated. The chemical composition and the antifungal activity of B. trimera and B. dracunculifolia EOs and the effect of EOs against Botrytis cinerea and Colletotrichum acutatum was determinate in vitro by mycelial growth (contact and volatile phase) and conidia germination. The in vivo efficacy study consisted of spraying the EO in harvested grapes of Vitis labrusca x Vitis vinifera cv. Isabela followed by inoculation with the fungus. The major compound found in B. trimera essential oil (BtEO) was carquejyl acetate and in B. dracunculifolia essencial oil (BdEO) were beta-pinene, ledol, spathulenol and limonene. For in vitro tests, BdEO showed a fungistatic action, whereas as BtEO showed fungicidal action. For this reason, the later was selected for in vivo testing. For in vivo test, the all concentrations of EO (200, 400 and 600 ppm) (mu L mL(-1)) were efficient, reducing the incidence and severity of disease caused by B. cinerea and C. acutatum, both as preventive and curative treatments. These results are promising and indicate that the BtEO might be further investigated as natural alternative to synthetic fungicides for the control of rots on grapes diseases.