Effects of Propiconazole on Exserohilum turcicum in Laboratory and Field Studies. Kira L. Bowen, Former Graduate Research Assistant, Department of Plant Pathology, University of Illinois, Urbana 61801. W. L. Pedersen, Associate Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. Plant Dis. 72:847-850. Accepted for publication 7 June 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0847.

Propiconazole inhibited mycelial growth of Exserohilum turcicum, the causal organism of northern leaf blight, but did not inhibit conidial germination. Conversely, mancozeb inhibited only conidial germination. In greenhouse experiments, lesion numbers on plants and rates of lesion expansion were inversely proportional to the rate of propiconazole application. Propiconazole slowed lesion expansion for 17 days, and reduced the rate of disease development in the field when applied at 3-wk intervals, relative to weekly applications of mancozeb.