First report of powdery mildew caused by Golovinomyces cichoracearum on Tragopogon dubius in Korea.
In July 2015, dozens of plants of T. dubius exhibiting powdery mildew symptoms were found in Daegu, Korea. Powdery mildew colonies first appeared as thin, white patches, but soon progressed to abundant hyphal growth on both sides of the leaves and stems. Severe infections caused leaf withering and premature senescence. Based on morphological characteristics, sequence analysis of the rDNA internal transcribed spacer region and pathogenicity, the causal agent was identified as G. cichoracearum. Associations of T. dubius and Golovinomyces have been reported in Europe. This is thought to be the first report of powdery mildew caused by G. cichoracearum on T. dubius in Korea. The field observations suggest powdery mildew could limit expansion of this invasive weed in Korea.