The fungitoxic activity against Penicillium digitatum, P. italicum, Botrytis cinerea and Alternaria citri of 12 essential oils (EO) distilled from medicinal plants is reported. The results of the in vitro trials show strong fungitoxic activity of Thymus capitatus (L.) Hofmgg EO, which inhibited the growth of the 4 fungi at a concentration of 250 ppm (v/v). The other 11 essences reduced the development of the fungi from 95% to 9% at 250 ppm (v/v). The fungitoxic activity of T. capitatus EO (75, 150, and 250 ppm) on healthy orange fruits, inoculated with P. digitatum (108 conidia ml-1) by spraying and placed in 10-litre desiccators, was weak at atmospheric pressure (3-10% inhibition at all 3 concentrations), while in vacuum conditions (0.5 bar) conidial mortality on the exocarp was high (90-97% at all 3 concentrations). These data proved not to be statistically different from treatments with thiabendazole-TBZ (2000 ppm). SEM observations showed that T. capitatus EO vapours altered the morphology of P. digitatum hyphae and conidia. The gas-chromatographic analyses of thyme EO indicated that carvacrol was present at 81-83%, p-cymene at 4.5-5%, Beta-terpinene at 2.6-3.3%, caryophyllene at 1.5-1.6%, Alfa-myrcene at 1.6%, linalool at 1.1-1.2%. Carvacrol proved to be the most important fungitoxic compound among the thyme EO constituents, but, unlike thyme EO, it caused alterations to the fruit at the concentration of 75 ppm.
Fungitoxic Activity of Twelve Essential Oils Against Four Postharvest Citrus Pathogens: Chemical Analysis of Thymus capitatus (L.) Hofmgg Oil and Its Effect in Subatmospheric Pressure Conditions
Arras G;
2001
Abstract
The fungitoxic activity against Penicillium digitatum, P. italicum, Botrytis cinerea and Alternaria citri of 12 essential oils (EO) distilled from medicinal plants is reported. The results of the in vitro trials show strong fungitoxic activity of Thymus capitatus (L.) Hofmgg EO, which inhibited the growth of the 4 fungi at a concentration of 250 ppm (v/v). The other 11 essences reduced the development of the fungi from 95% to 9% at 250 ppm (v/v). The fungitoxic activity of T. capitatus EO (75, 150, and 250 ppm) on healthy orange fruits, inoculated with P. digitatum (108 conidia ml-1) by spraying and placed in 10-litre desiccators, was weak at atmospheric pressure (3-10% inhibition at all 3 concentrations), while in vacuum conditions (0.5 bar) conidial mortality on the exocarp was high (90-97% at all 3 concentrations). These data proved not to be statistically different from treatments with thiabendazole-TBZ (2000 ppm). SEM observations showed that T. capitatus EO vapours altered the morphology of P. digitatum hyphae and conidia. The gas-chromatographic analyses of thyme EO indicated that carvacrol was present at 81-83%, p-cymene at 4.5-5%, Beta-terpinene at 2.6-3.3%, caryophyllene at 1.5-1.6%, Alfa-myrcene at 1.6%, linalool at 1.1-1.2%. Carvacrol proved to be the most important fungitoxic compound among the thyme EO constituents, but, unlike thyme EO, it caused alterations to the fruit at the concentration of 75 ppm.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
