Petiole rot of hosta, caused by the soilborne fungi Sclerotium rolfsii and S. rolfsii var. delphinii, appeared first in the southern United States. The rapid spread of petiole rot in the Midwest U.S. during the past decade has caused increasing concern among wholesale producers, retailers, and buyers.
Iowa State University
Xu, Zhihan and Gleason, Mark L., "Evaluation of Hosta Cultivarsfor Resistance to Petiole Rot" (2007). Iowa State Research Farm Progress Reports. 856.