1. UC IPM
Purplish discoloration caused by downy mildew, <i>Peronospora sparsa,</i> a plant-pathogenic oomycete infecting a rose leaflet (right of center).
Purplish discoloration caused by downy mildew, Peronospora sparsa, a plant-pathogenic oomycete infecting a rose leaflet (right of center).
Credit: John F. Karlik