Studies on the Host Range of Sclerotium delphinii Welch

Abstract

In a note published previously (8) the writer mentioned that A. J. Mix had made an isolation of Sclerotium delphinii Welch from Ajuga reptans. The organism was observed in a rock garden where in addition to Ajuga it was parasitizing Sedum acre and Lysimachia nummularia. This marked the first time this species had been isolated in Kansas, although Sclerotium rolfsii Sacc., a closely related species, is listed by Bartholomew (1) as occurring in the state. Figure 1, left, is a photograph of the strain of S. delphinii isolated from Ajuga, and, right, a typical culture of S. rolfsii growing on potato dextrose agar slants. In the course of a general study of this isolate from Ajuga it was decided to investigate the host range and make a few comparisons with S. rolfsii. The latter, because of its wide geographical distribution and economic importance as a plant pathogene, has received considerable mention in the literature and is known to be parasitic on nearly two hundred hosts. Sclerotium delphinii, on the other hand, has been reported on only about forty species. These have been compiled and are listed in Table I. Unfortunately some workers gave only the common names for some of the hosts, and where there was doubt as to the correct scientific name, either just the genus name or common name is listed.