First Report of Powdery Mildew of Onion (<i>Allium cepa</i>) Caused by <i>Leveillula taurica</i> in the Pacific Northwest

Fig. 2. Internal mycelium (hyphae encircling host mesophyll cells) of Leveillula taurica parasitizing Allium cepa.



Image from Plant Health Progress article:
First Report of Powdery Mildew of Onion (Allium cepa) Caused by Leveillula taurica in the Pacific Northwest