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Mildew symptoms seen recently in Piedmont on Origanum vulgare, Campanula rapunculoides, and Oenothera biennis.

Abstract

This article describes the symptoms of powdery mildew observed recently for the first time in Italy on Origanum vulgare, Campanula rapunculoides, and Oenothera biennis. During the month of January 2011, about 30 000 plants of O. vulgare about 3 months old were grown in plastic pots. Approximately 90% of the cultivated plants were presented with the symptoms of an intense attack of powdery mildew that had already begun to emerge during the previous autumn. Both leaf pages (especially the top) appeared colonized by whitish mycelium of the fungus that spread unevenly and caused small necrotic areas. ITS analysis identified the causal agent as Golovinomyces biocellatus. In the summer of 2011, 50 plants of C. rapunculoides of 6-9 months, grown in a private garden in a location Biella, were affected by whitish mycelium which colonized both leaf edges (especially the upper). The leaves and stems dry up and the most affected plants appeared very emaciated. Based on ITS analysis, the isolated causal organism was identified as Golovinomyces orontii. In the summer of 2011, about 30 plants of Oenothera biennis, grown in large containers placed in a partially shaded, in a private garden in the province of Biella, were affected by powdery mildew. The mycelium of the fungus stretched over the leaves, along the stems, on peduncles and tubules. Based on morphological characteristics, the pathogen was identified as Erysiphe sp.