Over the years, Nature Safe users have reported a significant reduction in the incidence of snow mold on turf that is treated regularly with Nature Safe the previous growing season. It is particularly noticeable where, for one reason or another, the normal application of snow mold preventative fungicide was not applied. Normally, if no preventative treatment is made, and the winter conditions are severe, the result is a considerable amount of dead grass from snow mold. Snow mold can be devastating even where a preventative treatment is applied. So, it is especially remarkable that very little damage occurs when no chemicals are applied in the fall.
That is exactly what happened at The Woods Golf Club in Green Bay, Wisconsin this past winter. Due to poor weather conditions, Ed Hoover, the Superintendent at The Woods, was unable to make an application of snow mold control fungicide on his Poa annua fairways. Poa is one of the most susceptible species to snow mold.
We know that Green Bay winters are usually bad from watching the famous Green Bay Packers play on the “frozen tundra,” but the winter of 2007-2008 was one of the most severe. Several feet of snow blanketed the area all winter and there were many periods where cold snow melt water ran across the underlying turf. You could not imagine better conditions for a severe infestation of snow mold.
When the snow finally melted, Ed was sure that his fairways would be devastated. Much to Ed’s surprise there was only superficial damage on the leaf tips. Ed said that in previous years snow mold completely killed the grass and he had to either seed or sod. This year was different. All the turf was alive and it grew out of the superficial leaf damage. Naturally, Ed and the club were ecstatic.
How did this “miracle” occur? The only thing Ed did differently last summer was to use Nature Safe 15-2-8 on his fairways. He made three applications at the rate of ¾ pounds of nitrogen per 1,000 square feet. These applications were made in May, June and August. Ed felt that his fairways last summer were the best they have ever been, but he had no inkling of the extra benefits that he was going to get from his Nature Safe usage.
What happened here is really no mystery. Research conducted by Dr. George Lazarovits1 shows that as beneficial soil microbes consume the energy contained in the high levels of amino acids in Nature Safe, they give off gasses that are toxic to many pathogens in the soil. These gasses are more toxic to pathogens that are in a dormant stage than they are to actively working pathogens. When Nature Safe is applied on a regular basis during the growing season the toxic gasses kill more and more of the dormant pathogens (such as snow mold) each time it is applied. That means that the inoculums normally available to start an outbreak of disease would not be present to create a problem when weather conditions become ideal.
Nature Safe will not eliminate snow mold and it will still be necessary to apply a snow mold control fungicide. It is safe to say that any snow mold that occurs will be much less of a problem than it would be on areas not treated with Nature Safe and that any applied snow mold control fungicides will be more effective.
It’s important to make sure that no one is being misled as to the winter benefits of Nature Safe. For winter disease benefits, Nature Safe should be applied at least three times during the summer months so that the gasses being given off by the microbes have a chance to kill as much inoculums as possible. One late fall application will certainly help, but it will not be sufficient to achieve the kind of results that were observed at The Woods Golf Club. For turf that is susceptible to snow mold, the time to get it started on Nature Safe is to apply it first thing in the spring and continue throughout the summer.
More About Snow Mold
Snow mold is a fungal disease that appears in early spring as the snow melts. There are two types of snow molds, gray and pink, that become active under the snow cover.
Gray snow mold survives hot summer temperatures in the soil or in infected plant debris as sclerotia, resistant fungal structures, while pink snow mold survives as mycelium or spores in infected plant debris. Fungal growth begins in the winter, beneath a cover of snow on unfrozen ground. Growth can take place at temperatures slightly below freezing and may continue after snow melt, as long as the grass remains cool and wet. Gray snow mold activity stops when the temperature exceeds 45°F or the surface dries. Pink snow mold activity may continue during wet weather in the fall and spring, as long as the temperature is between 32°F and 60°F.
Symptoms first appear in the turf as circular, straw colored patches when the snow melts in the spring. These patches continue to enlarge as long as the grass remains cold and wet. Grass within the patch often has a matted appearance and colored fungal growth. The fungal growth may cover the entire patch or develop along the margins, with gray snow mold being white to gray in color and pink snow mold being white to pink in color. Occasionally, fungal fruiting bodies (mushrooms) may be seen emerging from infected turf. Hard structures, called sclerotia, may also develop on the leaves and crowns of plants infected by gray snow mold, not pink. The sclerotia are spherical in shape and roughly the size of a pinhead. Their presence helps to distinguish gray snow mold from pink snow mold.