First Record and Notes on Pleiochaeta Setosa in Minnesota

Abstract

Lupinus albus L. (white lupine) is a newly introduced crop in Minnesota. Throughout the 1989 and 1990 growing seasons, dark brown, sunken lesions developed on leaves, stem, pods, and roots on being grown under irrigation. The lesions were observed only on leaves under non-irrigated conditions. The fungus isolated from these lesions and roots was Pleiochaeta setosa (Kirchn.) S. J. Hughes, which is known to be a major root and foliar pathogen on Lupinus spp. in Australia (Wood, 1982); It is also pathogenic on Lupinus spp. and other genera of the Fabaceae from New Zealand (Dingley, 1969), South Africa (Du Plessis and Truter, 1953), Europe (Germar, 1939; Gondran, 1988; Moral et al., 1981; Pulselli, 1928), North America (Pirozynski, 1974) and South America (Diehl et al., 1982; Orlando and Orlando, 1983). Weimer (1952) reported P. setosa in North America on blue lupines from Alabama, Florida, Georgia, and Louisiana. Crop loss attributed to P. setosa elsewhere merits noting the occurrence of this fungus on cultivated in Minnesota. We provide an expanded formal description including new observations on septate appendages and conidiogenous cells. Koch's postulates (1884) were completed in an environmental growth chamber set at 21 C, 93% RH, with an alternating 12 h light regime. The fungal inoculum was twice-autoclaved millet seeds upon which P. setosa isolated from roots was grown for 3 wk. The P. setosa ramified millet seeds were layered immediately below L. albus