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Disease Note.

First Report of Powdery Mildew (Oidiopsis taurica) of Gazania. S. T. Koike, Santa Barbara County Department of Agriculture, Santa Barbara, CA 93110. T. E. Tidwell and K. L. Kosta. California Department of Food and Agriculture, Sacramento 95814. Plant Dis. 72:546. Accepted for publication 16 March 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0546E.

Chlorotic blotches were observed on adaxial surfaces of older lanceolate and pinnatifid leaves of gazania (Gazania splendens Hort. ex E. G. Henders. & A. Henders.) in Santa Barbara County, California, during 1986-1988. Oidiopsis taurica (Lev.) Salmon was identified on abaxial leaf surfaces corresponding to the lesion sites (1,2). Conidia were borne singly, rarely catenulate, on branched conidiophores that emerged from host stomata. Terminal conidia were obclavate and measured 54.7 X 19.0 µm; secondary conidia measured 54.7 X 19.1 µm. Cleistothecia were not observed. This fungus caused numerous yellow blotches or lesions on gazania leaves; infected leaf tissue did not become necrotic, however. Powdery mildew occurred on gazania in many ornamental plantings and was found extensively throughout 10 acres of commercial plantings grown for seed. This is the first report of any powdery mildew disease on gazania. Voucher specimens have been deposited at the California Department of Food and Agriculture as Gilbert Stout Herbarium specimen 701.

References: (1) H. J. Bosewinkel. Bot. Rev. 46:167,1980. (2) J. C. Correll et al. Plant Dis. 71:248,1987.