Brown dead leaves on limbs of Raywood ash limb that were killed by drought stress in combination with a weak pathogen, Botryosphaeria stevensii. This disease complex is called Raywood ash canker and decline.

Raywood ash orange leaves dying from Raywood ash decline of 15-year-old street trees. Caused by drought stress in combination with a secondary (weak) pathogen (Botryosphaeria stevensii). Modesto CA by JKC Credit: Jack Kelly Clark
Credit: Jack Kelly Clark