Examining Resistance to DMI Fungicides: Research at the University of Guelph

Dollar spot disease on Kentucky bluegrass showing the tip yellowing and a dark band at the base of the lesion. Photo courtesy Tom Hsiang

By Tom Hsiang, PhD

Propiconazole, a DMI fungicide, became registered for use on turfgrass in 1994. Due to the recent discovery of DMI-resistant isolates of the dollar spot pathogen in the Great Lakes States, there was concern resistance would develop in Ontario. This author started a study in 1994 to look at baseline sensitivity of the dollar spot pathogen to DMI fungicides. A graduate student, Wayne Barton, worked on sensitivity to propiconazole, while other students and lab members worked on sensitivity to other DMI fungicides.

From eight locations throughout southern Ontario, the team found most populations of the dollar spot pathogen were sensitive to DMI fungicides. However, there was one population near the U.S. border with reduced sensitivity to DMI fungicides, and the team suspected there had been previous exposure to DMI fungicides in this population.

Read the full article: Examining Resistance to DMI Fungicides

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