First report of powdery mildew caused by Golovinomyces biocellatus on Origanum vulgare L. "Compactum" cultivated in Italy.
During January 2011, a new powdery mildew was observed on potted plants of Origanum vulgare "Compactum" cultivated in a farm near Albenga (SV), in Liguria region (northern Italy). Symptoms of the disease are reported. The perfect stage of the microorganism was not observed. Morphological characteristics of the pathogen observed on the microscope and the ITS (Internal Transcribed Spacer) analysis permitted to classify the causal agent of the disease as Golovinomyces biocellatus. Finally, the main causal agents of powdery mildew previously reported on Origanum species are listed and some strategies to prevent and to control this disease are given. This is the first report in Italy of G. biocellatus on O. vulgare.