Using plant essential oils to control Fusarium wilt in tomato plants

We assessed the use of essential oils in controlling Fusarium wilt in tomato. Clove oil, thyme oil, rosemary oil and their major components, as well as the two commercial products, Bioxeda (based on clove oil) and Sporatec (containing rosemary oil, clove oil and thyme oil) were assessed in vitro and in a greenhouse pot trial. The in vitro tests consisted of evaluating the development of fungal colonies on agar medium supplemented with the tested products (i.e., the oils, their major component, and Bioxeda and Sporatec) at various concentrations. In addition, the percentage of conidia germination was determined after using the products at different concentrations. The greenhouse trial was carried out on 5-week-old tomato seedlings cv. Cuore di Bue di Albenga. Tomato seedlings were transplanted into pots containing pasteurized soil after the roots had been dipped in a conidial suspension of Fusarium oxysporum f. sp. lycopersici. Immediately after transplanting, the treatments were carried out in the soil surrounding the roots of tomato plants with essential oils at various concentrations. Control treatments were also carried out. In vitro tests showed that almost all the investigated products were able to inhibit mycelial growth and conidial germination. The best results were obtained with clove oil and its major component eugenol. Rosemary oil showed the lowest inhibitory activity. Greenhouse pot experiments indicated that all the tested products were able to reduce Fusarium wilt in tomato. The best results were obtained with clove oil, however rosemary oil was also effective in controlling F. oxysporum f. sp. lycopersici. The performance of the essential oils was lower than the performance of the reference product.