The broad-spectrum, systemic fungicides propiconazole (1) and tebuconazole (2) are used to control rust in peppermint (Mentha piperita L.). An analytical method, using gas chromatography combined with detection by high-resolution mass spectrometry, was developed to allow for the simultaneous monitoring of both pesticides in peppermint leaves and oil. Field trials were established to determine the rate of dissipation of tebuconazole and propiconazole in peppermint crops. Three applications of each fungicide were trialed at two rates (125 and 250 g of active ingredient (ai)/ha). At harvest, 64 days after the final application, propiconazole was detected at levels of 0.06 mg/kg and 0.09 mg/kg of dry weight, and tebuconazole was detected at 0.26 and 0.80 mg/kg dry weight, in identical trials. Rates of dissipation of propiconazole and tebuconazole were lower at a second trial site, where three applications of 125 g/ha ai for each fungicide resulted in residue levels of 0.21 mg/kg for both pesticides, detected 89 days after the last application. Propiconazole and tebuconazole were detected in the distilled oil at levels between 0.02 and 0.05 mg/kg and between 0.011 and 0.041 mg/kg, respectively. Propiconazole had a higher tendency to co-distill with the peppermint oil, with 0.7% of that present in the vegetative material ending up in the oil, compared to 0.09% of tebuconazole.

Two more Tasmanian bryozoans belonging to the Amathia genus have been found to contain amathamide alkaloids. A. convoluta has given a new compound, amathamide G, while A. pinnata contains the previously described amathamide C.

The solvent extract of Tasmannia lanceolata from a small community of plants was examined over 230 days of the growing season. The results from gas chromatography were analyzed using cluster analysis and principal coordinate analysis. Two distinct groups of plants were identified, based on polygodial content and the entire range of components detected. The use of as many components as possible is recommended for the analysis, to give the most complete representation of the composition of the extracts. Within the low-polygodial group, the tendency was for polygodial levels to remain constant over time, whereas in the high-polygodial group, concentrations varied. Keywords: Cluster analysis; Tasmannia lanceolata; polygodial; gas chromatography

The broad spectrum, systemic fungicides tebuconazole and propiconazole are used to control rust in boronia (Boronia megastigma Nees). Gas chromatography combined with either a benchtop quadrupole mass spectrometer or a high-resolution mass spectrometer allowed for the monitoring of both pesticides in boronia leaves, flowers, and concrete. Field trials were established at two sites to determine the rate of dissipation of tebuconazole and propiconazole in boronia. At site 1, two application rates of 125 and 250 g active ingredient/hectare (ai/ha) tebuconazole were employed. Treatments were repeated 17 days later. At harvest, 286 days after the final application, tebuconazole was detected at levels of 0.06 +/- 0.05 and 0.5 +/- 0.1 [mg/kg +/- standard error, on a dry matter basis (DMB)] in the leaves collected from plots treated with 125 and 250 g ai/ha of tebuconazole, respectively. The oil produced from the flowers collected at the final harvest had residues of tebuconazole at levels of 0.06 +/- 0.03 and 0.10 +/- 0.08 mg/kg for the 125 and 250 g ai/ha application rates, respectively. Two repeat applications of 125 g ai/ha propiconazole were also used at site 1. Residues of propiconazole were detected at 0.09 +/- 0.03 mg/kg (DMB) 286 days after the final application. At site 2, treatments of 125 g ai/ha of tebuconazole were applied twice. At harvest, 279 days after the final application of tebuconazole, residues were recorded at 0.30 +/- 0.09 mg/kg in the leaves (DMB) while the oil produced had 0.20 +/- 0.07 mg/kg.

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