Increase in Incidence and Severity of Target Turfgrass Diseases by Certain Fungicides

Field and laboratory studies were conducted to determine if in a situation of fungicide resistance, the use of the fungicide in question might increase the severity of the target turfgrass disease. Applications of either a mixture of cycloheximide and thiram or triphenyltin hydroxide to tall fescue (Festuca elatior var. arundinacea) colonized by a strain of Rhizoctonia solani resistant to these fungicides increased the incidence of Rhizoctonia blight