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.