Phyllosticta multicorniculata on Abies spp. in the Northeastern U.S

Several needle blight fungi affect natural regeneration and Christmas tree plantations of Abies spp. in northeastern North America. Of these, Phyllosticta multicorniculata Bissett & Palm has been reported from A. balsamea (L.) Mill. in Ontario and Prince Edward Island, and from A. concolor (Gordon & Glend.) Lindl. ex Hildebr. in Wisconsin (1). In Quebec, P. multicorniculata was reported as an endophyte on symptomless needles of A. balsamea (2). In 1994, we collected this fungus in Grafton County, NH, defoliating lower branches of A. balsamea Christmas trees. In July and August 1996, we examined infected A. concolor Christmas trees in Lamoille County, VT. In July, approximately 50% of the 1996 needle complement on the lower 1 m of the crowns was infected and by August the incidence of infection on these branches increased to 75 to 100%. Less severe blighting occurred up to 1.5 m. Dead needles of the 1995 complement bore abundant, mostly empty, pycnidia of P. multicorniculata. The dead and dying distal ends of the 1996 needle complement bore abundant pycnidia of P. multicorniculata in various stages of maturation. This is the first report of this pathogen on Abies spp. in the northeastern U.S. The conidia from actively-sporulating pycnidia bore more numerous and longer appendages (1 to 16, average 7, up to 38 µm long) than the dried herbarium specimens of various ages used in the species description (1 to 5, up to 7 µm long) (1), or similarly reported from culture (2). References: (1) J. Bissett and M. E. Palm. Can. J. Bot. 67:3378, 1989. (2) L. Petrini et al. Sydowia 43:148, 1991.