It is that time of the year again where for the most part turfgrass maintenance activities have slowed, but not completely stopped. What you see above is a very common turfgrass disease called Gray Snow Mold. This is a fungal disease that, on golf courses or sports fields with shortly mowed turf, it can be more impactfull than normal 2" or higher turfgrass. For locations with short mowing heights there can be some type of protective fungicide application performed late in the fall to help prevent the disease. We don't do any kind of fungicide application, for many reasons, but more importantly this is a disease that is not much of a problem for our turf height .
Gray Snow Mold is a fungal disease which is dormant fungi in the turf canopy in the summer. Then as temps drop in the late fall and winter months, the fungi becomes active. Gray Snow Mold forms under prolonged snow cover and will continue to propagate as long as the snow continues to cover the canopy. This desease is usually only found on north sides of builds where the snow has a chance to last for long periods of time. Recently with warm winds, areas that have been under snow cover since the November storms have finally started to open up so I can take a look. As you can see we have some Gray Snow Mold.
Gray Snow Mold grows like many other fungal infections and requires cool damp conditions for growth. I had a good feeling we would get a fair amount of Gray Snow Mold this year because the turf was not completely dormant when the first heavy snow fall hit. This provided a perfect scenario for fungal growth. If the turf and soil had been completely dormant or frozen prior to the snow we would have much less infection.
Initially these infections tend to be circular patches roughly 6-8" in diameter and will continue to grow until individual colonies coalesce into larger patches that can cover entire areas. Looking closer, the patches have a white to gray color and have hair like structures called Mycelia that envelope the leaf blades. This fungus feeds primarily on the leaf tissue of the plant and usually does not go after the crowns of the plant and for this reason it is usually not a major problem in taller turfgrass.
Here on campus when these areas become open, we send our staff out with lawn rakes to literally rake the turf to break up the matted areas which allows dry air into the canopy. This will quickly shut down the fungus and will prevent further damage. We then will go back to the hardest hit areas in the spring to do heavy slit-seeding to regenerate any turf we may have lost during the event.
Having snow cover is great for moisture in the long dry winters to protect plants from drying out but as you can see there can be a downside to a good snow cover.
Never a dull moment in the Turfgrass industry.