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The activity of two biofungicides based on Bacillus subtilis and Ampelomyces quisqualis alone and in combination with fungicides against Podosphaera xanthii on zucchini was tested in five experimental trials carried out under greenhouse conditions. The population of P. xanthii used throughout the work for artificial inoculation was able to cause slight infections on zucchini plants treated with the field dosages of azoxystrobin and penconazole. B. subtilis when combined with azoxystrobin against P. xanthii at the recommended field dosages provided better powdery mildew control than the two control measures alone. Such results were consistent throughout the different trials. A similar synergistic effect was shown by the combination of A. quisqualis with myclobutanil: however, in this case, more studies are necessary to confirm the consistency of that phenomenon. The results obtained in this study support the possibility of a synergistic effect among the biocontrol agent B. subtilis and QoI fungicides. Such interaction is very interesting because of the presence of resistance towards QoI in the populations of P. xanthii.

Two novel brominated metabolites, tribromocacoxanthene (3) and tetrabromocacoxanthene (4),have been isolated from a marine sponge of the Cacospongia genus (family Thorectidae ) along with 12-epideoxoscalarin (2). The structures of compounds (3), systematic name (2S,4aS,9aS)-2,7-dibromo-4a-bromomethyl-1,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene, and (4), systematic name (2S,4aS,9aS)-2,5,7-tribromo-4a-bromomethyl-l,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene , were deduced from analysis of 1H and 13C n.m.r. data and that of (3) was confirmed by X-ray crystallographic structure analysis which provided the absolute configuration. The two new compounds are the first tricyclic examples of a carbon skeleton previously isolated only from algae. The chemotaxonomic implication of the isolation of these new compounds is discussed.

Two novel brominated metabolites, tribromocacoxanthene (3) and tetrabromocacoxanthene (4),have been isolated from a marine sponge of the Cacospongia genus (family Thorectidae ) along with 12-epideoxoscalarin (2). The structures of compounds (3), systematic name (2S,4aS,9aS)-2,7-dibromo-4a-bromomethyl-1,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene, and (4), systematic name (2S,4aS,9aS)-2,5,7-tribromo-4a-bromomethyl-l,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene , were deduced from analysis of 1H and 13C n.m.r. data and that of (3) was confirmed by X-ray crystallographic structure analysis which provided the absolute configuration. The two new compounds are the first tricyclic examples of a carbon skeleton previously isolated only from algae. The chemotaxonomic implication of the isolation of these new compounds is discussed.