Last December saw record warmth across the upper Midwest, igniting a debate about whether to reapply snow mold fungicides or not. Based on the results of previous research we had conducted, my opinion was that most superintendents in the region had lost much of their fungicide protection during the month. However, whether disease would develop over a wide area still depended on a number of things that we couldn’t predict (snowfall, temperature, etc). With how warm the winter had been to date and the proclamations of a very warm ‘El Nino’ winter, we felt that in general snow mold wouldn’t be that severe and course-wide reapplications wouldn’t be needed. As the snows melted in March, very little snow mold was apparent and it was clear that the environmental conditions just hadn’t been favorable for disease.
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As luck would have it, last November we also initiated a follow-up research project to the one mentioned above that looked at the persistence of Banner MAXX (with and without the anti-transpirant Transfilm) throughout the winter…and how that persistence translated to Microdochium patch suppression in the growth chamber. As shown in Figure 1, the warm temperatures and frequent rainfall caused propiconazole concentrations to plummet in the 14 days following the application and by 28 days following the application there was no detectable fungicide present. Not surprisingly, disease development on cores transferred from the field to the growth chamber increased correspondingly, with a significant jump 14 days following the application and near 100% disease by 28 days following. The inclusion of Transfilm did not have any impact on the persistence of propiconazole or the development of disease in this particular year.
What seems quite clear from this first year of research is that most snow mold fungicide applications made last year in November were completely gone from the turf system by the end of 2015. However, it was also quite clear that just because you don’t have fungicide present doesn’t mean you will necessarily get disease…which was the case with most Midwestern superintendents this past spring. We hope to learn more about the persistence of snow mold fungicides in various environments during the next two winters.
Special thanks to the Canadian Allied Turfgrass Research Group, Wisconsin Golf Course Superintendents Association, Syngenta Professional Products, and PBI Gordon for providing funding of this project. Please feel free to call (608-576-2673) or email (email@example.com) if you have any questions or want to discuss the research results further.