Resistance to Maize Dwarf Mosaic Virus, Severity of Symptoms, Titer of Virus, and Yield of Sweet Corn. J. K. Pataky, Associate Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. J. F. Murphy, and Cleora J. D’Arcy. Former Graduate Research Assistant, and Associate Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. Plant Dis. 74:359-364. Accepted for publication 17 November 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0359.

Nineteen sweet corn hybrids were evaluated in field experiments for symptoms of maize dwarf mosaic (MDM), titer of maize dwarf mosaic virus (MDMV), and yield. Weak associations were observed between yield of sweet corn and titer of MDMV (r = ns to –0.79), yield and symptoms of MDM (r = –0.43 to –0.84), and titer of MDMV and symptoms of MDM (r = 0.66 to 0.92). All associations were influenced strongly by MDMV-resistant hybrids. Titer, symptoms, and yield were not associated among susceptible hybrids. Three types of resistance to MDMV were observed. Terminator and 87-5134 had resistance in which all plants remained asymptomatic and titer of MDMV in the youngest, fully expanded leaves did not differ from that in uninoculated plants. Plants of Seneca 258 segregated for symptom development. Titer of asymptomatic plants of Seneca 258 did not differ from that of uninoculated plants. Titer of symptomatic plants of Seneca 258 was lower than that of the most susceptible hybrid. Sundance and Wintergreen had partial resistance in which titer of MDMV and ratings of MDM symptoms were lower than those of the most susceptible hybrids but higher than those of uninoculated plants.