Occurrence of Breadfruit Rust, Caused by Uredo artocarpi, in Hawaii. D. E. Gardner, National Park Service CPSU, Department of Botany, University of Hawaii at Manoa, Honolulu 96822. Plant Dis. 75:968. Accepted for publication 8 April 1991. DOI: 10.1094/PD-75-0968A.
In December 1990, a rust was found on fallen leaves of breadfruit (Artocarpus altilis (S. Parkinson) Fosb.) in an ornamental planting at Panaewa Zoo near Hilo, Hawaii. In February 1991, conspicuous russeting associated with rust infection was found on otherwise healthy leaves of young, vigorous trees at the same site. The fungus, identified as Uredo artocarpi B. & Br., is known on Artocarpus in India and the Philippines and on islands of the South Pacific, but this is the first report of its occurrence in Hawaii. Uredinia are minute, phakopsoroid, and scattered singly or clustered in small groups on lower leaf surfaces. Urediniospores are prominently echinulate, broadly ellipsoid or ovoid, and hyaline, or nearly so. Small, irregular leaf spots, visible on both surfaces, are associated with uredinia and may be discrete or coalesce to produce the observed russeting. The potential impact of U. artocarpi on breadfruit production is not known.