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Epidemiology of Lirula abietis-concoloris on White Fir in California. Robert F. Scharpf, Pacific Southwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Berkeley, CA 94701. . Plant Dis. 72:855-858. Accepted for publication 26 April 1988. 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, 1988. DOI: 10.1094/PD-72-0855.

The disease cycle of Lirula abietis-concoloris, a needle pathogen of white fir (Abies concolor) in the central Sierra Nevada requires about 2 years for completion. New foliage was infected in the spring of 1984, but symptoms and signs did not appear until the summer of 1985. Hysterothecia began development in needles in late fall of 1985 and appeared mature by early spring. Opening of hysterothecia and release of ascospores did not occur in the field until May and June, and only then during periods of rain or overhead irrigation. In the laboratory, hysterothecia collected before May failed to open and cast spores under all temperature and moisture regimes tested, whereas those collected in May and June opened and dispersed spores at temperatures ranging from 5 to 28 C and for 11 days at 515 C. New foliage on trees receiving irrigation in June 1985 showed symptoms of heavy infection in 1986, whereas new foliage not receiving either rain or irrigation in May and June was nearly disease-free.