For golf courses already experiencing active dollar spot outbreaks this year, it is crucial to reassess the dollar spot management plan for this season and prepare accordingly. Last year, we encountered unprecedented pressure from dollar spot due to consistently favorable conditions, such as prolonged periods of leaf wetness. Predictions indicate that localized heavy rainfall and higher relative humidity may increase due to global warming. Consequently, managing and controlling dollar spot disease in turf, which thrives in prolonged wet conditions, will likely become more challenging.
In May of this year, for instance, the average relative humidity was 5% higher than in May 2023, and the onset of conditions conducive to dollar spot occurred two weeks earlier than the previous year. As a result, we have already received two samples and five additional inquiries for dollar spot resistance assays, and this is just the beginning.
To manage dollar spot effectively on meticulously maintained turf areas like golf courses, fungicides are a primary tool, although cultural practices and biological controls can help to mitigate severity. However, the emergence of fungicide resistance complicates chemical control efforts, posing challenges to superintendents who invest substantial resources in fungicide applications. This resistance leads to increased stress, financial costs, and reduced playability.
Identifying effective fungicides and excluding ineffective ones is foundational to devising successful chemical control strategies. Dollar spot resistance assays are crucial in evaluating the efficacy of various fungicide classes. The UMass Turf Pathology Lab offers assays for five highly utilized fungicide classes (DMI, SDHI, Dicarboximide, Benzimidazole, Fluazinam). The assay report provides insights into which fungicide classes to use or avoid.
We strongly recommend conducting these assays early in the season. Failing to control dollar spot effectively with ineffective fungicides can accelerate pathogen resistance development against effective treatments under favorable conditions. This narrows your options for chemical control, emphasizing the importance of proactive management strategies.
If you notice a decline in the effectiveness of fungicides, such as needing to apply them more frequently, consider submitting samples of dollar spot to the UMass Turf Pathology Lab. This step not only helps you explore alternative disease management options but also supports ongoing research and monitoring of resistant fungal populations. Take action early to enable more effective disease management and cost savings. For inquiries about dollar spot resistance assays or to utilize this service, please contact Mr. Soonhong Min at soonhongmin@umass.edu or Dr. Geunhwa Jung at jung@umass.edu.
Here are some general guidelines for submitting samples:
- Collect 2-3 cup cutter plugs from affected areas and wrap them with a wet paper towel to prevent drying.
- Soil samples are not necessary for submission.
- Ensure the samples contain visible dollar spot infection centers.
- Overnight shipping is recommended, except on Fridays.
Submitted by: Dr. Geunhwa Jung and Soonhong Min, Graduate Student, Jung Lab
