Incidence and Severity of Stewart's Bacterial Wilt on Sequential Plantings of Resistant and Susceptible Sweet Corn Hybrids. J. K. Pataky, Department of Crop Sciences, University of Illinois, Urbana, 61801. J. A. Hawk and T. Weldekidan, Department of Plant and Soil Sciences, University of Delaware, Newark, 19717-1303; and P. Fallah Moghaddam, Department of Plant Biology, University of Illinois, Urbana 68101. PLANT DIS. 79:1202. Accepted for publication 23 August 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-1202.

Naturally occurring Stewart's wilt, caused by Erwinia stewartii, was monitored in nine trials in Delaware, Illinois, and Missouri on sequential plantings of resistant, intermediate, and susceptible sweet corn (Zea mays) hybrids. Disease incidence and severity differed among trials, among early and late plantings, and among hybrids differing in resistance. Resistant hybrids were easily differentiated from susceptible hybrids by incidence or severity, but reactions of intermediate hybrids were not always distinguishable from those of resistant and susceptible hybrids. Development of Stewart's wilt differed among plantings within and between years. Incidence of Stewart's wilt on the early planting of the susceptible hybrids did not reliably indicate subsequent levels of disease. Nevertheless, it seems prudent to implement control measures for late plantings if Stewart's wilt is abundant at seedling stages of early plantings.