Galls, Diseases, and Pests - Toyon Scab
Venturia inaequalis
Scab fungi cause spotting on many parts of plants, but it is usually not a problem unless they develop on fruit trees. The spotting is actually a small area of tissue overgrowth. Scab seems to be more prevalent in years with wet Springtimes.
This toyon leaf not only shows scab fungi but also evidence of Toyon Thrips. Read more about the thrips here.