Which fungicide class provides the most effective snow mold control?
The switch from August to September doesn’t only signal the onset of football season, for many superintendents it also signals the onset of snow mold season. There are a host of factors that go into choosing an effective snow mold program at your facility: budget, course expectations, disease pressure, etc. Further complicating matters is that there are a number of products and product mixtures that provide effective snow mold suppression. Over half of the 108 treatments tested in our snow mold trial last winter provided exceptional control under extreme pink snow mold pressure at Wausau CC in central Wisconsin.
If you look at most of those effective treatments, they have two things in common. First, they all have multiple active ingredients, which is required under the heavy snow mold pressure that central and northern Wisconsin experiences. Second, most include an active ingredient from the demethylation inhibitor (DMI) class. In fact, if you could only use one fungicide class for snow mold control, I would argue that the data supports the DMI fungicides as the most effective one. Highly effective snow mold products and mixtures including Instrata, Interface + Triton FLO, Torque + 26/36, Lexicon + Trinity, and Turfcide + Concert all include DMI fungicides. Further, removing just the DMI fungicide from a 3-way mixture causes a disproportionate decrease in disease control. The Torque + 26/36 shown in the figure above provided exceptional control as a 3-way, and when Torque (a DMI fungicide) was applied alone disease severity increased from 1.8% to 34%. However, when 26/36 (a 2-way mixture) was applied in the same trial without the DMI, disease severity jumped all the way to 72%! The same phenomenon was observed with Interface + Triton FLO; as a 3-way mixture there was 4% disease, with Triton FLO alone there was 31% disease, and with Interface alone there was 63% disease. Under the lower snow mold pressures commonly observed over much of the country, a DMI applied alone may provide all the protection you need.
Now I am not saying that DMI’s alone will provide adequate protection under moderate to heavy snow mold pressures when applied alone, they won’t. However, our research suggests that they may be the most important part of that 2, 3, or even 4-way mixture. So if you are looking to reduce costs this fall with your snow mold program, I wouldn’t recommend doing so by eliminating the DMI.
For more information about Wisconsin’s snow mold research, including full reports and pictures of each treatment, please visit www.tdl.wisc.edu/results and come to your own conclusions about what products may be best for your situation.