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Commercial plant essential oils obtained from 26 plant species were tested for their antifungal activity against Phytophthora cactorum and Cryponectria parasitica. Good antifungal activity against P. cactorum was achieved with the essential oil derived from thyme ( Thymus vulgaris) and bay ( Pimenta racemosa) at 28 × 10-3 mg/ml air concentration. Inhibition rates of bay and red thyme were 69.1% and 100%, respectively, at 28 × 10-3 mg/ml air concentration. In a test with C. parasitica, the inhibition rates of bay and red thyme oil were 75.2% and 100%, respectively, at 28 × 10-3 mg/ml air concentration. The inhibition rate of cade ( Juniperus oxycedrus) essential oil was 63.0%, but other oils were ≤40%. Analysis by gas chromatography-mass spectrometry led to the identification of 17 and 20 compounds, respectively, in the oils of bay and red thyme. The antifungal activity of the identified compounds was tested individually using standard compounds. Phenol and alcohol compounds were generally more toxic than hydrocarbons. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Medicinal plant essential oils and components from Asiasarum sieboldi were tested for their insecticidal activities against the rice weevil Sitophilus oryzae, using a fumigation bioassay. Responses varied with plant material and concentration. The LC50 value of A. sieboldi essential oil against rice weevil was 2.37 µg/ml air. Analysis by gas chromatography-mass spectrometry led to the identification of 20 compounds from A. sieboldi essential oil. Among identified compounds, five main compounds were tested for their insecticidal activity against rice weevil and compared to the toxicity of dichlorvos. Responses varied with compound and dose. Eucarvone was the most toxic, followed by safrole, with LC50 values of 3.32 and 11.27 µg/ml, respectively. LC50 values of other compounds were >25 µg/ml. The LC50 value of dichlorvos was 0.0081 µg/ml. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Commercial plant essential oils obtained from 11 Myrtaceae plant species were tested for their antifungal activity against Phytophthora cactorum, Cryponectria parasitica and Fusarium circinatum. Good antifungal activity against Phytophthora cactorum was achieved with the essential oil derived from Leptospermum petersonii at 28 × 10−3 mg/ml air concentration. Inhibition rates of Eucalyptus citriodora and Melaleuca quinquenervia were 35.4% and 33.6% at 28 × 10−3 mg/ml air concentration, respectively. In a test with C. parasitica, inhibition rates of E. citriodora and L. petersonii were 29.4% and 38.5%, respectively. Only L. petersonii essential oil showed antifungal activity against F. circinatum. Analysis by gas chromatography-mass spectrometry led to identification of 16, 15 and 12 compounds, respectively, in the oils of L. petersonii, M. quinquenervia and E. citriodora. The antifungal activity of the identified compounds was tested individually using standard or synthesized compounds. The inhibition rates of citronellol, neral, geraniol and geranial were 100% against P. cactorum at 28 × 10−3 mg/ml air concentration. In a test with C. parasitica, the inhibition rates of neral and geranial were 61.7% and 68.9% at 28 × 10−3 mg/ml air concentration. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]