Snow mold season approaching
Even with above normal temperatures for most of the United States this week, snow mold season is almost upon the northern United States. The two major snow molds are gray (pathogen: Typhula incarnata, Typhula ishikariensis) and pink snow mold (pathogen: Microdochium nivale). Gray snow mold requires snow cover since pathogen development is optimum under wet, cold (32-40 degrees F) conditions. Long matted turf can provide an environment favorable for gray snow mold (and thus the reason to continue mowing until the turf ceases growth) but the severity is not as great as with a snow cover. Generally speaking, moderate gray leaf spot severity occurs if snow cover is less than 40-60. Severe gray snow mold damage occurs when snow cover exceeds 90 days.
Pink snow mold is active under cool (just above freezing) wet conditions. These conditions exist under snow cover but can also occur without snow cover. Pink snow mold is especially severe if it attacks the crowns of the turfgrass plant. If snow mold is a concern fungicide applications will need to be made. If snow cover is not present, if conditions remain wet and cool (40 to 45 degrees F) additional applications may be required.
Soil temperature map
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