Coniothyrium bartholomaei on yucca looks similar to Mycosphaerella leaf spot. Photo is of C. bartholomaei. Photo found at: http://ipmnet.org/plant-disease/disease.cfm?RecordID=1160

Fruiting bodies (pycnidia) of C. bartholomaei on yucca are the black structures in center of the tan area. Photo found at: http://ipmnet.org/plant-disease/disease.cfm?RecordID=1160

Iris leaf spot on the plant. Photo provided by: R.K. Jones, North Carolina State University, Bugwood.org

Close-up of iris leaf spot. Photo provided by: R.K. Jones, North Carolina State University, Bugwood.org

Wilting caused by botryosphaeria canker on rhododendron. Photo found at: http://www.umassgreeninfo.org/fact_sheets/diseases/botryosphaeria_canker.pdf and taken by R. K. Jones, Diseases of Woody Ornamentals and Trees. APS Press