Avocado leaves with brown lesions due to the fungi that cause branch canker and dieback, formerly called Dothiorella canker. The disease is caused by Phomopsis (=Diaporthe) species and various fungi in the Botryosphaeriaceae family.

Dothiorella canker, Botryosphaeria dothidea = Dothiorella gregaria. Brown necrosis along margins and tip of avocado leaves, foliage close-up. Ventura Co.  Credit: David Rosen
Credit: David Rosen