Essential Oils for Alternative Teak Rust Control

ABSTRACT The objectives of this study were to evaluate the effect of lemon grass, citronella grass, Mexican-tea and noni essential oils on urediniospore germination of Olivea neotectonae , the agent responsible for rust in Teak (Tectona grandis L.f.); to evaluate the phytotoxic effect of these essential oils on teak seedlings; and to evaluate the use of essential oils to control rust in teak plants when preventively and curatively applied. We found that the noni and lemon grass essential oils inhibited 100% of urediniospore germination. On the other hand, the essential oils from noni and lemon grass caused phytotoxicity when applied to seedlings at concentrations of 2000 and 1500 μL L-1, respectively. The major constituents found in lemon grass essential oil were Geranial and Neral, while Octanoic Acid was found in noni oil. Lower values in the area below the rust progress curve were observed with the preventive application of lemon grass and noni essential oils.摘要 本研究设定三项核心目标：其一，评估柠檬草、香茅、墨西哥茶及诺丽精油对柚木（Tectona grandis L.f.）锈病病原菌橄榄斑锈菌（Olivea neotectonae）夏孢子萌发的影响；其二，测定上述精油对柚木幼苗的药害效应；其三，探究精油分别以预防性与治疗性施用方式时，对柚木锈病的防治效果。研究结果表明：诺丽精油与柠檬草精油可100%抑制夏孢子萌发。与之相对，当以2000 μL L⁻¹、1500 μL L⁻¹的浓度分别施用于柚木幼苗时，诺丽与柠檬草精油会引发药害。柠檬草精油的主要成分为香叶醛（Geranial）与橙花醛（Neral），而诺丽精油中检出辛酸（Octanoic Acid）。预防性施用柠檬草与诺丽精油的处理组，其锈病病程曲线下面积更低。