Submitted to: IMA Fungus
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2015
Publication Date: 11/20/2015
Citation: Demers, J.E., Romberg, M.K., Castlebury, L.A. 2015. Microcyclic rusts of hollyhock (Alcea rosea). IMA Fungus. 6(2):477-482. Interpretive Summary: Rust fungi cause many serious diseases of ornamental and crop plants around the world. Several species are known to cause disease on hollyhocks and are frequently intercepted by quarantine inspectors. One species, Puccinia heterogenea, is subject to strict quarantine regulations as it is not present in the United States. Another similar rust fungus, Puccinia malvacearum, is already present in the United States. In this study, DNA sequences and spore characteristics were used to distinguish between the two pathogens, as well as four other species occurring on hollyhocks. Images and descriptive information are included. Plant pathologists, quarantine officials and other scientists will be able to use this information to accurately distinguish between these fungi and prevent the spread of P. heterogenea to the United States and other countries where it does not yet occur.
Technical Abstract: Rust fungi infecting hollyhock and other plants in the Malvoideae are frequently intercepted at ports of entry to the United States, particularly the species Puccinia malvacearum and P. heterogenea. These two species can be difficult to distinguish and can be further confused with other, less common species of microcylic rust fungi infecting hollyhock: P. heterospora, P. lobata, P. platyspora, and P. sherardiana. Molecular phylogenetic analysis showed that P. malvacearum and P. heterogenea are closely related, along with P. sherardiana and P. platyspora. A key to the six microcyclic Puccinia species infecting hollyhock is presented.