There have been several reports of hosta crown rot recently. Symptoms of the disease include marginal yellowing and browning of the leaves, beginning with the lower leaves. As the disease progresses, the leaves discolor entirely and wilt. In the final stages of the disease, most of the leaves completely collapse and lay flat on the ground. Because the bases of the petioles are rotted, the leaves can be easily pulled away from the crown of the plant.
Signs of the disease also can be observed. Small round fungal fruiting structures, about the size of mustard seeds, appear at the base of the infected petioles. These structures, called sclerotia, are a cream color when young, but then progress to a dark, brick red color. The sclerotia are long-term survival structures of the fungus.
Images of the symptoms and signs of hosta crown rot can be found on the Plant Disease Clinic website . Click on the "Special Feature" section.
Crown rot is caused by the fungus Sclerotium rolfsii and is a very serious disease of hosta. Unfortunately, the fungus has a wide host range, so it can be a problem on many garden plants. Good sanitation practices are therefore important in preventing the spread of this fungus. Many gardeners choose to eliminate infected plants and the surrounding soil. Some fungicides are available to help control the disease, but they are not readily available to the home gardener.
Detailed information about crown rot on hosta and other ornamentals can be found in the Iowa State University bulletin, SUL 8 Crown Rot - A Serious Disease of Hosta and Other Ornamentals . This bulletin is available through your local extension office or from the Iowa State University Extension Distribution Center, 515-294-5247. Contact the Center by e-mail at firstname.lastname@example.org .
This article originally appeared in the 7/23/2004 issue.