Smut of Manchurian Wild Rice Caused by Ustilago esculenta in California. T. Watson, California Department of Food & Agriculture, Pest Detection Branch, 1700 Herndon Road, Ceres 95307. T. E. Tidwell, and D. G. Fogle. California Department of Food & Agriculture, Analysis & Identification Branch, 1220 N St., Sacramento 95814. Plant Dis. 75:1075. Accepted for publication 17 May 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1075D.
An illegal 0.05-ha planting of Manchurian wild rice (Zizania latifolia
(Griseb.) Turcz. ex Stapf) infected with the smut fungus, Ustilago
esculenta Henn., was discovered near Modesto, California. The original
plants had been brought into the United States in violation of
federal quarantines that prohibit entry of the host and of the fungus
that poses a threat to native wild rice. The plants were being grown
for the edible "galls" (enlarged culms) resulting from infection by the
smut fungus (1). When the galls, which measured up to 3 cm in
diameter, were cut open, dark sori measuring 1 × 5-10 mm filled
with teliospores typical of the fungus (2) were found. Specimens of
the infected plants were submitted as herbarium material to the USDA/
APHIS/PPQ facility in Beltsville, Maryland, and the rest of the plants
were eradicated. This is the first report of the disease in a field situation
in North America.