Disease Note

An Outbreak of Stewart’s Bacterial Wilt of Corn in Ontario, Canada. T. R. Anderson, Agriculture Canada, Harrow, Ont. N0R 1G0. Plant Dis. 70:603. Accepted for publication 11 February 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-603f.

Stewart’s bacterial wilt caused by Erwinia stewartii (E. F. Smith) Dye occurred on dent and sweet corn (Zea mays L.) in southwestern Ontario in 1985. A gram-negative yellow bacterium isolated from diseased leaves produced chlorotic streaks typical of Stewart’s bacterial wilt when inoculated on corn seedlings in the greenhouse. A disease survey in Ontario Corn Performance Tests indicated mild to severe foliar symptoms in Essex and Kent counties. Disease severity was lower in cooler areas of the province. Disease severity in Essex County was greater than expected on the basis of a winter temperature index of 77 during 1984–1985. This is the first report of Stewart’s wilt of dent corn in Ontario since 1932.