Studies on the nature of the synergistic effects of pyrazophos and propiconazole in Pyrenophora teres
1992
Zeun, R. (Hannover Univ. (Germany). Inst. fuer Pflanzenkrankheiten und Pflanzenschutz) | Sachse, B. | Buchenauer, H.
Investigations on the lipid metabolism of mycelium of Pyrenophora teres revealed that single treatments with pyrazophos and propiconazole as well as the application of mixtures of both fungicides reduced the total content of phospholipids after an incubation period of 2 days. In contrast to the effects of the single fungicides, pyrazophos-propiconazole mixtures induced an accumulation of lysophospholipids. Incubation of mycelium with pyrazophos or propiconazole for 21 days resulted in increased contents of di- and triglycerides in comparison to untreated mycelium. This effect was increased by the fungicide combination. Gaschromatographic analysis of sterols revealed a decrease of ergosterol contents and an accumulation of ergosterol precursors after propiconazole treatment, while the total sterol content was slightly increased. Pyrazophos had no effect on the composition of different sterol fractions, however, the total sterol content was slightly reduced. Application of the mixture of both fungicides resulted in a more severe reduction of the ergosterol contents than the single treatment of propiconazole. Ergosterol precursors were accumulated in mycelium treated with both propiconazole and the fungicide mixture. While the individual fungicides did not induce ion efflux in mycelium of P. teres, membrane permeability of the mycelium was increased in the presence of the fungicide mixture. Toxin production of P. teres was almost completely suppressed by propiconazole and by the mixture pyrazophos-propiconazole. With extended incubation periods of the fungicides in the liquid cultures of P. teres, propiconazole content decreased less rapidly when pyrazophos was present compared to a single treatment of propiconazole
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