1. UC IPM
Oval-shaped tan lesions with concentric zones on onion leaf blades, caused by purple botch or Stemphylium leaf blight, <i>Stemphylium vesicarium.</i> Spores of downy mildew, <i>Peronospora destructor,</i> are also present.
Oval-shaped tan lesions with concentric zones on onion leaf blades, caused by purple botch or Stemphylium leaf blight, Stemphylium vesicarium. Spores of downy mildew, Peronospora destructor, are also present.
Credit: R. Michael Davis