Curative and suppressive activities of essential tea tree oil against fungal plant pathogens

Abstract

Timorex Gold based on the essential tea tree oil (TTO) derived from the Australian tea tree oil (Melaleuca alternifolia) plant has demonstrated high efficacy and a strong curative activity against black Sigatoka in banana and controlled it in stages 1, 2, 3, and 4 of disease development. Transmission electron microscope (TEM) examination of infected leaf sections treated with Timorex Gold revealed disruption of the fungal cell membrane and destruction of the fungal cell wall in disease development stages 4 and 5. Mineral oil and the fungicide difenoconazole, when applied alone, had no curative effect and did not disrupt the fungal cell wall or membrane, similar to the untreated control tissue. A single spray of Timorex Gold effectively controlled and suppressed powdery mildew in cucumber by causing the disappearance of 99% of established colonies recorded 1 or 2 days after the application and was effective for up to 8 days after application. Scanning electron microscope (SEM) examination of infected and Timorex Gold-treated leaves indicated strong shrinkage and disruption of fungal hyphae and conidial cells. The curative and suppressive modes of action of the Timorex Gold may explain its success in controlling both diseases.