TURFGRASS DISEASE IDENTIFICATION (P8)

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Snow Molds

Gray Snow Mold (Typhula Blight)

Causal Agent: Typhula incarnata, Typhula ishikariensis, Typhula idahoenis, and Typhula canadensis

Susceptible Turfgrass: All species of cool-season turfgrass

Symptoms: The symptoms of gray snow mold are evident after snow melts. It causes patches that are light brown, gray, or straw-colored and that measure less than 10 inches in diameter. The patches can increase to several feet and coalesce. Rust-, brown-, or black-colored sclerotia also appear on the infected leaves.

Snow Molds

Conditions Favoring Disease: Snow cover usually is necessary for this disease to cause damage. Gray snow mold is most severe when snow cover lasts more than 90 days.

Management Tips:

  • Mow turf regularly until dormancy.
  • Avoid heavy applications of water-soluble nitrogen sources in late fall prior to dormancy.
  • Prevent excess snow from accumulating by using shrubs, windbreaks, or a snow fence.
  • Prevent snow compaction on the turf.
  • Remove snow from turf in the spring.
  • Lightly fertilize turf in early spring to encourage new growth.
  • In the fall, use fungicides prior to snow cover, and in late winter, use them to promote a quick spring recovery if snow cover melts or is removed.

Occasionally occurs in: CA, DE, IL, IN, KS, KY, MD, MO, NC, NV, OR, TN, VA, WV.

Frequently occurs in: CO, CT, IA, ID, MA, ME, MI, MN, MT, ND, NE, NH, NJ, NY, OH, PA, RI, SD, VT, WA, WI, WY.

Labeled products:

Microdochium Patch (Pink Snow Mold)

Causal Agent: Microdochium nivale

Susceptible Turfgrass: Most species of cool-season turfgrass

Symptoms: Pink snow mold causes water-soaked patches that are yellow, tan, or salmon-colored and that measure 1 to 8 inches or more in diameter. The patches, which can coalesce, are pale pink around the edges. Spores are produced in white or salmon-colored sporodochia that are found on the dead tissue. Blighting can occur in streaks from spores tracking on the equipment wheels.

Microdochium Patch

Conditions Favoring Disease: Pink snow mold favors temperatures of less than 60°F. It is more severe where snow has fallen on unfrozen soil or in cold, rainy weather. Microdochium nivale is commonly called Fusarium patch (see page 46) in the absence of snow cover—but the causal organism is the same.

Management Tips:

  • Regularly mow turf until dormancy.
  • Avoid heavy applications of water-soluble nitrogen sources in late fall prior to dormancy.
  • Maintain balanced fertility.
  • Avoid using lime. Alkaline soils enhance disease development.
  • Reduce thatch.
  • Prevent excess snow from accumulating by using shrubs, windbreaks, or snow fences.
  • Apply contact and/or systemic fungicides in the fall and reapply during periods of no snow cover.
  • Shade and leaf wetness are also key factors in disease severity.

Occasionally occurs in: AL, AR, AZ, CA, GA, NC, NM, OK, TN, TX, VA.

Frequently occurs in: CO, CT, DE, IA, ID, IL, IN, KS, MA, MD, ME, MN, MO, MT, ND, NE, NH, NJ, NV, NY, OH, OR, PA, RI, SD, UT, VT, WA, WI, WV, WY.

Labeled products:

 

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