Fungicides Nuarimol Research Articles

Effects of soil temperature on the efficacy of ergosterol biosynthesis inhibitor fungicides for control of Ustilago bullata

AbstractThe effects of different soil temperatures on the efficacy of ergosterol biosynthesis inhibitor (EBI) fungicides applied as seed treatments for the control of seedling infection of prairie grass Bromus willdenowii (Kunth) by the head smut fungus Ustilago bullata (Berk.) were measured in a glasshouse experiment. The fungicides nuarimol, triadimefon and triadimenol+fuberidazole controlled infection at 17.5deg;C and below, but were less or non‐effective above 20.0°C. In a second experiment, nuarimol and propiconazole seed treatments reduced seedling emergence and caused stunting of seedlings, but these effects occurred equally over a range of temperatures from 15.0 to 27.5°C. Soil temperatures (3 cm depth) at a typical field site often exceeded 20°C during early autumn and late spring. Although EBI fungicide seed treatments show promise for U. bullata control, care will be required with their routine use because their efficacy in warm soils may be reduced, and they can have growth retardant effects on prairie grass seedlings.

The ultrastructure of sporidia of Ustilago avenae after treatment with the fungicides nuarimol and imazalil nitrate

AbstractUltrastructural changes were observed in sporidia of Ustilago avenue (Pers.) Rostr. after treatment with the fungicides nuarimol and imazalil nitrate. Electron microscopic studies of ultrathin sections, as well as of freeze‐fracture replicas, showed that nuarimol caused the following marked changes in the ultrastructure of the cells: increased cell wall thickness and invaginated plasmalemma, with concentrations of extracytoplasmic vesicles in some places between plasmalemma and the cell wall; pores were visible in the septa. Nuarimol‐treated sporidia were characterised by vacuolisation and accumulation of lipid bodies. Compared with nuarimol, imazalil nitrate caused small cytological changes; elongation of the sporidia and enlarged cell diameters, as well as an increased thickness of the septa, were observed, and an enhanced number of mitochondria with reduced diameters were found.