Dollar spot is the most economically important disease on golf course turf in the New England region. Fungicides are an important tool for dollar spot disease management along with effective cultural practices such as dew/guttation removal, fertilization, rolling, and increasing air circulation.
Resistance to four fungicide classes [benzimidazole, dicarboximide, demethylation inhibitor (DMI), and succinate dehydrogenase inhibitor (SDHI)] has been documented in dollar spot. Reduced in vitro sensitivity to fluazinam (no field resistance observed, yet) was recently published (Shi et al., 2023). Cross- and multiple-resistance to the fungicides makes managing the disease even more challenging.
Dr. John Kaminski of Penn State University has stated that if managers can learn to assess the fungicide resistance of dollar spot and choose the most effective fungicides, he estimates that they might avoid, on average, three fungicide applications a year. "You are looking at $7,500 to $10,000 per course," (source: ScienceDaily)... not to mention overall reductions in fungicide use and good IPM.
Our UMass Turf Pathology Lab offers a fee-based service to golf course superintendents and the turf industry with in vitro sensitivity assays to multiple fungicide classes (DMI, SDHI, dicarboximide, benzimidazole, and fluazinam). We also provide a written report outlining specific recommendations for managing fungicide resistance tailored to specific golf course properties.
If you experience lack of control (e.g., shorter interval) using the above-mentioned fungicides, please consider submitting samples to the UMass Turf Pathology Lab. If you have any interest in this service or have questions regarding the assays in dollar spot, please contact Dr. Geunhwa Jung at jung[at]umass[dot]edu (jung[at]umass[dot]edu)
Submitted by: Dr. Geunhwa Jung