PLANT&FOREST

Suppression of melon powdery mildew and tomato leaf mold disease by the antifungal activity of tea tree (Melaleuca alternifolia) essential sil

Mun Haeng Lee1   Sang-Keun Oh2,*   

1Fruit Vegetable Research Institute, Chungchengnam-do Agricultural Research & Extension Service, Buyeo 32514, Korea
2Departmentof Applied Biology, College of Agriculture & Life Sciences, Chungnam National University, Daejeon 34134, Korea

Abstract

Essential oils (EOs) have been shown to be plant-extracted antimicrobial agents. However, there are limited studies investigating the efficacy of EOs against pathogens. Among them, tea tree oil (TTO) is extracted from Melaleuca alternifolia, which is also used as an antifungal agent. In this study, the effect of TTO was investigated on the suppression of melon powdery mildew caused by Podosphaera xanthii and tomato leaf mold disease caused by Passalora fulva. Both powdery mildew and leaf mold diseases were significantly suppressed by a spray of TTO. Eighty percent of powdery mildew and 81% of leaf mold disease of the control value were suppressed by 0.5% TTO liquid, when sprayed 3 times every 7 days on the melon and tomato leaves. Inhibition of mycelial growth was also greatly affected by different concentrations of TTO against four different fungal pathogens. Ninety-eight percent of Pseudocercospora fuligena, 97% of P. fulva, 95% of Botrytis cinerea, and 94% of Phytophthora infestans mycelial growth were inhibited by 0.2% to 1.0% of TTO contained in plate media, respectively. However, phytotoxicity in plants by the TTO treatments was revealed when melon and tomato leaves were sprayed with a 1% and 2% concentration of TTO, respectively. Therefore, our findings show that TTO has high antifungal effects against various plant pathogens that occur during crop cultivation. We also suggest that when applying TTO to plant leaves, it is necessary to establish an accurate treatment concentration for different crops.

Figures & Tables

Fig. 1. Effect of tea tree oil (TTO) on mycelium growth of four phytopathogenic fungi on potato dextrose agar (PDA). (A) , (B) , and (C) were grown at 25 ± 1℃ for 7 days (B. cinerea, and 20 days [ and ), respectively. was also grown at 20 ± 1℃ for 10 days (D). Each TTO concentration was 0.1, 0.2, 0.5, 1.0, and 2.0%, respectively. Control plates were 0.5% tween 20 alone.