First report of powdery mildew caused by Golovinomyces orontii on Galium aparine in China.
From April through June 2014, a powdery mildew was observed on 40% of the Galium aparine plants in a nursery in the city of Shangqiu in Henan, China. The adaxial surfaces of leaves and stems were covered with small white colonies that expanded and eventually covered whole leaf surfaces. The abaxial leaf surfaces and flowers were covered by white mycelium very rarely. The causal pathogen was identified as Golovinomyces orontii based on morphological, molecular and pathogenicity analyses. This is thought to be the first report of powdery mildew caused by Golovinomyces orontii on Galium aparine in China.