As you can see in these pictures, coming out of this record-setting winter we most likely will be dealing with a lot of snow mold issues. Most snow mold preventative applications will last you 120 days or right around that magic number. With this extended snow season, we are gearing up and ready for the advanced snow mold presence on the course. I anticipate a lot of my time this spring will be spent tank-mixing and spraying diseased areas. Lets say you sprayed PCNB and Iprodione around mid October... 120 days from Mid October gets you to mid February, and as we all know, its LATE APRIL and we still have plenty of snow on the ground. Our attempts at clearing the greens were in vein; not two days after clearing greens and trying to melt the ice on them Mother Nature dealt us a good 6 to 8 inches of heavy snow...Even though the right precautions were taken last fall, snow mold is something that we will deal with year in and year out. I will try and educate and elaborate on what these two diseases are and some of the means of curing the problem.
There is a major difference in the two diseases. Gray snow mold is caused by two species of Typhula: T. incarnata and T. ishikariensis. (1) Pink Snow Mold is caused by Microdochium nivale.
For the sake of this post and me not wanting to get too crazy with details, I will focus primarily on Gray Snow Mold.
The symptoms of Gray snow mold develop under continuous snow cover of usually more than 60 days, something that we have obviously encountered this year. As I write this post, it is yet again snowing!!! Although this is a typical rule, there are always cases where there was not continuous cover and gray snow mold still popped up.
Gray snow mold has sclerotia (black or brownish, naked-eye visible bodies) that survive from year to year. This is a great way to ID gray snow mold from pink snow mold because pink doesn't have these bodies. As you can see in the photos, there is a cobweb-like appearance near the edge of the melting snow. That is referred to as the mycelial mass, something that in these pictures is highly visible, even from a distance. Usually, snow molds form circles, but can coalesce to take over very large areas. The ideal growth for gray snow mold is long periods of wet, cool weather on unfrozen ground. If you get a large amount of snowfall before the grass is able to "harden-off" and freeze the soil, this is another scenario that is favorable to disease development. Heavy fall applications of Nitrogen with lush growth before the plant hardens-off makes that area susceptible to the disease after the snow melts off. When you think about it, there is a lot more leaf tissue due to the excessive fertilizing, which makes more areas for these sclerotia to hide and over-winter. This excess tissue ( not always directly correlated to fertilization in the fall) also leads to more thatch. Increased height of cut before the snowfall and accumulations of leaves will also harbor the pathogen and increase the amount you will see in the spring.
Notice how some of the spots have joined together to form irregular patches? This is called coalescing and accounts for why snow molds can take over large areas of turf.
Check out the mycelial mass ( puffy, almost like light snow) that is raised up off the crown of the plant and up on the leaf blades.
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Comments and questions or corrections are encouraged! I am not claiming to be an expert and if there is something that sounds wrong to you, please leave a comment! I love to learn more about what we are all experiencing and every one's thoughts are welcome.
