Outbreak of downy mildew caused by Peronospora belbahrii on Ocimum basilicum var. polosum in China.
In July 2016, downy mildew symptoms (grey and furry growth on the undersurface of infected leaves) were observed in sweet basil (Ocimum basilicum var. polosum) in the Shunyi and Daxing districts of Beijing, China. In less than 10 days, disease incidence increased from 30 to 100%. The causal pathogen was isolated and identified as Peronospora belbahrii based on morphological, molecular and pathogenicity analyses. This is thought to be the first report of P. belbahrii causing downy mildew on sweet basil in mainland China.