Page 14 - GreenMaster Fall 2022

or two applications of iron sulfate made prior to snow cover didn’t provide any snow mould suppression. However, we hypothesized that if we made repeated iron sulfate applica- tions throughout the fall, it would more effectively suppress the snow mould fungi prior to snow cover and provide disease suppression.
In 2019, we made six applications of Extreme Green 20 iron sulfate heptahydrate at the rate 183 g per 100 sq m (6 oz per 1000 sq ft) to locations in northern Wisconsin (Minocqua), central Wisconsin (Wausau), and southern Wisconsin (Madison). We then came back and rated the plots for snow mould severity the following spring. The results from this study were very clear and indicated that no snow mould suppression was observed at any of the three locations, even with 6 applications of iron sulfate made to each site (Figure 5).
It also didn’t matter the type of snow mould, since speckled snow mould (Typhula ishikariensis) was observed in Minocqua, pink snow mould (Microdochium nivale) was observed in Wausau, and gray snow mould (Typhula incarnata) was observed in Madison. It’s not entirely clear why iron sulfate didn’t suppress snow mould, but it’s likely that any initial knockback of the snow mould fungi in the fall wasn’t sufficient to suppress fungal and disease devel- opment for the entire winter.
MORE SNOW MOULD RESOURCES
Changes in product and climate are making snow mould suppression more unpredictable, and it’s impor- tant to stay up to date with the latest research. My program posts all of our research, both for snow mould and summer diseases, at our Turfgrass Diagnostic Lab research webpage (https://tdl.wisc.edu/ results/). I encourage you to visit the site and look over the research results for yourself to get a better under- standing of the most effective products on the market and how best to use them. If you have any questions, please email me at plkoch@wisc.edu. GM
Figure 4. The cutoff between no snow mould suppression and excellent suppression can be very sharp, as evidenced by this picture from Timber Ridge GC in Minocqua, WI, in spring of 2020.
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Figure 5. Not much ambiguity in these results. It didn’t matter the type of snow mould or the location, iron sulfate did not provide any appreciable suppression of snow mould in areas with extended snow cover.