Rust on Commelina diffusa in Hawaii. D. E. Gardner, Research Plant Pathologist, National Park Service Cooperative Park Studies Unit, University of Hawaii, Honolulu 96822. Plant Dis. 65:690-691. Accepted for publication 19 May 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/PD-65-690.

The uredinial state of a rust disease pathogen is widespread on Commelina diffusa, a common ground cover in Hawaii, and sometimes causes death of aboveground portions of the host. No telia have been observed. Although this rust on Commelina in Hawaii has been attributed to Uromyces commelinae, the rust fungus reported here is Phakopsora tecta or Physopella tecta. Sphaerellopsis filum produced prominent pycnidia in many uredinia. Voucher specimens were deposited in the USDA National Fungal Collection Herbarium in Beltsville, MD.

Keyword(s): Phakopsora commelinae.