Evaluación in vitro del potencial antifúngico del aceite esencial del orégano contra lasiodiploida theobromae aislada de cultivos de banano.

Abstract

anana is a strategic crop for the Ecuadorian economy; however, it suffers considerable postharvest losses due to diseases such as crown rot, caused by Lasiodiplodia theobromae. The prolonged use of synthetic fungicides has led to pathogen resistance, chemical residue accumulation in fruits, and negative environmental impacts, which has driven the search for natural, safe, and sustainable alternatives. The objective of this study was to evaluate the antifungal effect of oregano (Plectranthus amboinicus) essential oil on L. theobromae under in vitro conditions as a potential postharvest control alternative. The essential oil was extracted through steam distillation, using fresh plant material with 2.8 L of purified water at 110 °C for two hours. Afterwards, PDA culture media were prepared with oil concentrations of 100, 200, 300, 350, and 400 ppm, and inoculated with the fungus. Mycelial growth was measured daily for eight days and quantified using ImageJ® software. As for the results, the essential oil yield was 0.042% relative to the fresh plant mass used. Mycelial growth inhibition was 71.98% at 100 ppm and 97.30% at 300 ppm. From 350 ppm onwards, complete growth inhibition was observed. Although no statistically significant differences were found between 300 and 350 ppm, visible growth was still detected at 300 ppm; therefore, the visual minimum inhibitory concentration was established at 350 ppm. In conclusion, the essential oil of P. amboinicus demonstrated strong antifungal activity against L. theobromae, possibly due to the presence of bioactive compounds such as carvacrol and thymol. These findings position the oil as a promising natural alternative to synthetic fungicides, with potential application in the postharvest management of bananas.