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.

No abstract

No abstract

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 identi¼cation of 17 and 20 compounds, respectively, in the oils of bay and red thyme. The antifungal activity of the identi¼ed compounds was tested individually using standard compounds. Phenol and alcohol compounds were generally more toxic than hydrocarbons.

No abstract

Plant essential oils from 21 plant species were tested for their insecticidal activities against larvae of Lycoriella ingenua Dufour (Diptera: Sciaridae) by using a fumigation bioassay. Good insecticidal activity against larvae of L. ingenua was achieved with essential oils of Acorus gramineus Solander, Schizonepeta tenuifolia Briquet, and Zanthoxylum piperitum De Candolle at 25 microg/ml air. S. tenuifolia oil showed the most potent insecticidal activity among the plant essential oils. At 12.5 microg/ml air concentration, S. tenuifolia oil caused 96.6% mortality, but mortality decreased to 60% at 3.125 microg/ml air. Analysis by gas chromatography-mass spectrometry led to identification of three major compounds from S. tenuifolia oil. These three compounds were tested individually for their insecticidal activities against larvae of L. ingenua and compared with the toxicity of dichlorvos. Pulegone was the most toxic, followed by menthone and limonene with LC50 values of 1.21, 6.03, and 15.42 microg/ml, respectively. LC50 of dichlorvos was 8.13 microg/ml. Effects of S. tenuifolia and its components on growth of Pleurotus ostreatus (Jacq. ex Fr.) Kummer also were investigated.

Analysis by gas chromatography-mass spectrometry led to the identification of 26 compounds in Acorus gramineus essential oil. The antifungal activity of the identified compounds was tested singularly by using standard compounds. Allyl isothiocyanate and cis-asarone showed inhibition rates of 100% against P. cactorum at 28 mg/l air. In a test with C. parasitica and F. circinatum, allyl isothiocyante and cis-asarone showed moderate activity at 28 mg/l air.

Plant essential oils from 20 plant species were tested for their insecticidal activity against larvae of Lycoriella ingenua (Dufour) (Diptera: Sciaridae) by using a fumigation bioassay. Good insecticidal activity (>90%) against larvae of L. ingenua was achieved with essential oils of caraway seed Carum carvi (L.)], lemongrass [Cymbopogon citratus (D.C.) Stapf.], mandarine (Citrus reticulate Blanco), nutmeg (Myristica fragrans Houtt), cade (Juniperus oxycedrus L.), spearmint (Mentha spicata L.), cumin (Cuminum cyminum L.), and thyme red [Thymus vulgaris (L.)] oils at 30 X 10-3 mg/1 air. Among them, caraway seed, spearmint, cumin, and thyme red essential oils were highly effective against L. ingenua at 20 x 10(-3) mg/ml air. Analysis by gas chromatography-mass spectrometry led to identification of 4, 9, 8, and 17 compounds from caraway seed, spearmint, cumin, and thyme red oils, respectively. These compounds were tested individually for their insecticidal activities against larvae of L. ingenua, and compared with the toxicity of dichlorvos. Carvacrol, thymol, linalool, cuminaldehyde, p-cymen, terpinen-4-ol, and carvone was effective at 10 x 10(-3) mg/l. The insecticidal activity of dichlorvos was 60% at 10 x 10(-3) mg/ml. Effects of four selected plant essential oils on growth of oyster mushroom, Pleurotus ostreatus, also were investigated.