Eutypa Dieback of Sweet Cherry and Occurrence oiEutypa lata Perithecia in the Central Valley of California. G. P. MUNKVOLD, Assistant Professor, Department of Plant Pathology, Iowa State University, Ames 50011. J. J. MAROIS, Professor, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 78:200-207. Accepted for publication 28 October 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0200.

Eutypa lata was recovered from cankers on sweet cherry trees in three California counties. E. lata ascospores or mycelial isolates from these trees were inoculated into wounded sweet cherry branches or stems, grapevine stems, and apricot branches. With mycelial inoculum, cankers developed on 19 of 30 cherry branches. Inoculation date (April vs. November) did not affect the incidence of cankers or mean canker length, but did affect the extent of xylem necrosis. With ascospore inoculum, infection of pruning wounds ranged from 0 to 100%, depending on pruning date and the time between pruning and inoculation. Of six E. lata isolates from three different hosts (sweet cherry, grape, apricot), four caused cankers and/ or dieback of potted cherry trees within 14 mo after mycelial inoculations. Canker incidence ranged from 50 to 100% among the four isolates. An isolate from sweet cherry was as virulent to grape and apricot as isolates originating from each of these hosts. The teleomorph of E. lata was discovered in several locations in the Central Valley of California, a semiarid region previously believed to be too dry to support formation of the teleomorph. The abundance of this stage of the fungus was determined to be sufficient to provide a large amount of inoculum for infection of grapevines in the Central Valley. A large proportion of the newly discovered perithecia was on sweet cherry; smaller proportions were on grape and apricot. Sprinkler irrigation of orchards and vineyards apparently provided sufficient moisture for development of perithecia

Keyword(s): disease spread, Eutypa armeniacae, host range