Hopefully, you didn't forget the preventative application for snow mold caused byTyphulafungi this winter. If you did, keep it in mind for next winter, especially if you anticipate cold temperatures and heavy snowfall.

Quick Tip

Typhulablight strikes fast. You can be fine in autumn and then overwhelmingly get lost at seeing grayish-brown dead circles on putting greens or fairways during snowmelt. Fungi causingTyphulablight have been growing in the turfgrass thatch and rootzone as soil temperatures drop to 50 degrees Fahrenheit (F). You even don't know the fungi are there during autumn when cool-season grasses grow well until the harsh winter front hits, and snow covers the grasses.

Winter hardiness of turfgrass can be maximized through a combination of maintaining mowing heights, fertilizing and slowly reducing irrigation during autumn, but fungicides are often required to preventTyphulablight from killing closely mown turfgrass in the Northern states (Stier, 2005). The pre-emptive approach is a smart idea for those who simply cannot take a month or more to recuperate turfgrass damaged byTyphulablight in the next spring. Fungicide treatment is most effective if applied before onset of symptoms or before the fungi begin actively growing. It reduces initial fungus inoculum potential and alleviates the disease severity.

Figure 1. Sporocarps fruiting structures of Typhula incarnata observed at our snow mold field plots established at Gateway Golf Course in Land O' Lakes, Wis., on Oct. 28, 2005. T. incarnata produces pinkish, club-shaped sporocarps that are 0.5-1 inches in height.

Typhula incarnataandT. ishikariensisare two major causal fungal pathogens ofTyphulablight on most turfgrasses cultivated in the United States (Smiley et al, 2005). The fungus survives as tuber-like hardened mycelium, called sclerotia, throughout the summer. In late autumn sclerotia geminate and mycelium begins growing from them. Club-shaped sexual fruiting structures (sporocarps) are formed from sclerotia under certain environmental cues, including light, temperature, soil moisture and soil microorganisms.

BothT. incarnataandT. ishikariensisare often present together and cause snow mold damage at the same time, althoughT. ishikariensistends to be more dominant in the northern regions of Wisconsin, Minnesota and Michigan.Typhulablight becomes severe, with more than 60 days of snow cover, which provides the fungi with favorable conditions of high moisture and temperature above freezing (34-36 degrees F). Winter-stressed plants are slowly taken over byTyphulafungi, and eventually infected areas turn into patches of white to gray dead turf as snow recedes in early spring.

Quick Tip

Typhulablight season in Wisconsin and Minnesota varies depending on the latitude and winter weather conditions, but turf damage becomes apparent in March and April. Early fungicide applications are started in mid-October when the activity of the fungi is at its peak. Usually, more than one chemistry with multiple applications are recommended in areas where snow cover is longer and temperature is lower in winter.