Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2016
Publication Date: 11/23/2016
Citation: Lupien, S.L., Dugan, K.M., Ward, K.F., O'Donnell, K. 2016. Wilt, crown, and root rot of common rose mallow (Hibiscus moscheutos) caused by a novel Fusarium sp. Plant Disease. 101(2):354-358.
Interpretive Summary: This study reports on the discovery and characterization of a novel wilt and stem rot disease of several rose mallow cultivars (Hibiscus moscheutos L.) in a Washington state landscape. Hibiscus spp. are economically important ornamentals that rank third highest in the sales of deciduous shrubs within the U.S., with an estimated wholesale value of 23.2 million dollars annually. Therefore, given its value to the ornamental industry, emergent diseases of H. moscheutos could have important implications for the industry. Thus, the main focus of this research was to identify the pathogen using genetic data and assess whether it could induce disease on H. moscheutos cultivar Luna Rose in a pathogenicity experiment. The genetic data indicated that the Hibiscus pathogen was a novel, undescribed Fusarium species closely related to F. buharicum. The latter species, like the Hibiscus pathogen, is pathogenic on members of the mallow family (Malvaceae). Results of the pathogenicity experiment demonstrated that the novel Fusarium species was able to induce wilt and rot symptoms on cultivar Luna Rose. This study will be of interest to plant breeders and plant disease specialists because it alerts them of the need to take proactive phytosanitary measures to minimize the impact of this novel pathogen on the ornamental industry.
Technical Abstract: A new crown and root rot disease of landscape plantings of the malvaceous ornamental common rose mallow (Hibiscus moscheutos) was first detected in Washington State in 2012. The main objectives of this study were to complete Koch's postulates, document the disease sypmtoms photographically, and identify the causal agent using multilocus molecular phylogenetics. Results of the pathogenicity experiments demonstrated that the novel Fusarium sp. could induce vascular wilt and root and crown rot symptoms on H. moscheutos 'Luna Rose'. Maximum-likelihood and maximum-parsimony phylogenetic analyses of portions of translation elongation factor 1-a (TEF1) and DNA-directed RNA polymerase II largest (RPB1) and second largest subunit (RPB2) indicated that the Hibiscus pathogen was a novel, undescribed Fusarium species nested within the F. buharicum species complex (FBSC).