Fungitoxicity of Lippia scaberrima essential oil and selected terpenoid components on two mango postharvest spoilage pathogens

Lippia scaberrima, an aromatic shrub with medicinal properties, is indigenous to southern Africa. Essential oil obtained from aerial plant parts was assessed in vitro and in vivo for antifungal activity against Botryosphaeria parva and Colletotrichum gloeosporioides isolated from mango fruit. Exposure to oil vapour for 2 and 4 days caused inhibition of mycelial growth of both isolates. Three major terpenoids identified in the oil, limonene, R-(−)-carvone, and 1,8-cineole, as well as S-(+)-carvone, were individually evaluated in vitro. The two enantiomers of carvone, along with L. scaberrima oil, were found to have the highest fungistatic activity. Oil and carvone enantiomer fungicidal activities were less pronounced. The use of commercial wax coatings enriched with essential oils led to reduced fungal infection by both pathogens. Results of the in vitro and preliminary in vivo studies suggest that employing L. scaberrima oil to control postharvest pathogens is worthy of further investigation.