Essential Oils as a Control Alternative of Fusarium Falciforme, Responsible for Causing Onion (Allium cepa L.) Basal Rot Disease

Abstract

In Burkina Faso, onions (Allium cepa L.) are one of the main vegetable crops. It is a very important source of income for producers. However, its production is subject to loss, one of the main ones being disease caused by fungal pathogens, including Fusarium falciforme, which causes onions basal rot. This study aimed to contribute to the onion production improvement through agroecological methods by setting up a pathogenicity test and an antifungal test based on essential oils of local plants against Fusarium falciforme. For the pathogenicity test, a conidial suspension of each strain was produced at 1 x 106 conidia/ml using a haematimeter. It was carried out in the Biosciences Laboratory of Joseph KI-ZERBO University and in the greenhouse. A randomized block design with 04 replicates and 06 treatments was used. For antifungal test, the method by direct contact was used. The germination rate parameter was measured in the laboratory. The rate of emergence and damping-off were assessed in the greenhouse. The pathogenicity test results showed that the impact of Fusarium falciforme on onion seeds was relatively high in all pots. As regards the antifungal test, results showed a significant inhibitory effect of the essential oils used on the mycelial growth of Fusarium falciforme. All the essential oil concentrations of Cymbopogon citratus and Cymbopogon nardus were able to completely inhibit the fungus' growth. In contrast, the essential oil of Eucalyptus camaldulensis showed little mycelial growth at 1 %, 2 % and 3 % concentrations of 1.05 to 2.85 cm, with an inhibition rate of 63.83 % to 86.68 %. Based on these results, biopesticide-based biocontrol of Fusarium falciforme is therefore possible for onions basal rot management.