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Ecology and Epidemiology

Biology of Puccinia chondrillina in Washington. E. B. Adams, Area Extension Agent, N 222 Havana, Spokane, WA 99202; R. F. Line, Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Pullman, WA 99164. Phytopathology 74:742-745. Accepted for publication 20 March 1984. 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, 1984. DOI: 10.1094/Phyto-74-742.

Puccinia chondrillina is an autoecious, macrocyclic rust fungus, but in Europe where it is indigenous, pycnia and aecia are rare. In Washington, where P. chondrillina was released in 1978 for control of rush skeletonweed (Chondrilla juncea), all stages of the life cycle of the pathogen were consistently found. Uredia and telia were observed each year subsequent to release of urediospores in weed-infested areas, and pycnia and aecia were observed in the spring of 1980 and 1981. All stages of P. chondrillina were also produced in the greenhouse. Teliospores collected from field sites germinated and produced basidiospores that infected leaves and stems of C. juncea, but teliospores produced in the greenhouse did not germinate. Pycnia appeared 16 days after basidiospore-producing teliospores were placed over the plants, and uredinoid aecia appeared in a circle around the pycnia 14 days after cross-fertilization. Several uredial generations were observed. Teliospores developed in stem lesions on plants in the field beginning in July and were capable of germinating in November. Pycnia and aecia, however, were not observed in the field until early spring. During the unusually mild winter of 1980- 1981, the rust also overwintered as sporulating uredia and latent uredia and pycnia.