Microdochium Patch (Pink Snow Mold)
Pink snow mold develops during periods of snow cover, with symptoms of the disease becoming evident as the snow melts. The disease appears in roughly circular patches from 2 inches to 1 foot in diameter that are white or light tan in color. A ring of salmon or pink-colored growth is present on the outer edge of patches when the disease is actively developing. The infected leaves within the patches are usually collapsed and matted down upon themselves.
Microdochium nivale may also infect turfgrasses in the absence of snow cover during periods of cool, wet weather; in these cases, the disease is referred to as Microdochium patch. The symptoms of Microdochium patch are slightly different than pink snow mold. The patches are similar to pink snow mold in size and shape, but are reddish-brown or salmon-colored and greasy in appearance. When the disease is actively developing, the patches may be surrounded by a dark brown or bronze ring.
Host Grass Species
bentgrass, bermudagrass, bluegrasses
Month(s) with symptoms
November to March
spots, circles, patches (4 to 12 inches)
Foliar Symptoms - Location/Shape
blighting of entire leaves
Foliar Symptoms - Color
pink, white, tan
mycelium, jelly-like spore-masses
Note: Still not sure if this is the right disease? The Turfgrass Disease Identification program may be helpful. Or consult the experts at the Turf Diagnostics Lab. Check the TurfFiles glossary for definitions of unfamiliar terms.
FACTORS AFFECTING DISEASE DEVELOPMENT
Disease activity is most severe when snow falls on unfrozen ground; however, activity can occur without snow cover during cool (less than 60°F) wet weather. Excessive foliar growth and thatch buildup are the most important factors encouraging development of pink snow mold and Microdochium patch. Restricted air movement, poor soil drainage, inadequate levels of potassium, and heavy traffic can also enhance the disease. The disease may also develop under tree leaves that remain on the turf for long periods during cold, wet weather.
Do not apply nitrogen when cold weather is expected or before the first expected prolonged snow cover. Continue mowing in the fall until foliar growth stops completely. These steps will prevent a buildup of lush foliage that is highly prone to pink snow mold or Microdochium patch.
Improve surface drainage, control traffic patterns, reduce thatch accumulations, and aerify regularly in areas that have been severely affected by the disease in the past. Prune trees and remove unwanted vegetation that impedes air movement. Frequently remove leaves and other debris during autumn and winter from turf that is not covered with snow.
In regions where heavy snow is anticipated, take steps to minimize the duration of snow cover. Erect snow fences or plant landscape plants in strategic locations to prevent excess snow accumulation. Prevent traffic on snow-covered turf, as compacted snow will melt more slowly and increase damage from pink snow mold.
Fungicides are effective for control of pink snow mold and Microdochium patch. In the case of pink snow mold, apply fungicides before snow cover to prevent disease development. Mapping and spot-treatment of areas where pink snow mold is most severe can significantly reduce fungicide expenditures. In regions where prolonged snow cover does not occur, apply fungicides when symptoms of Microdochium patch are first observed.
Resistance Risk (2)
chlorothalonil + propiconazole + fludioxonil**
DMI + nitrile + phenylpyrolle
iprodione + thiophanate-methyl**
26/36, Dovetail, Fluid Fungicide
3336, Fungo, Systec, T-Bird, T-Storm, Tee-Off, TM
flutolanil + thiophanate-methyl
benzimidazole + carboxamide
chlorothalonil + thiophanate-methyl**
benzimidazole + nitrile
Spectro, ConSyst, Peregrine, Tee-1-Up, TM/C
pyraclostrobin + boscalid**
carboxamide + QoI
26GT, IPro, Iprodione Pro, Raven
Banner MAXX, Kestrel, Kestrel MEX, ProPensity, Propiconazole, Propiconazole G-Pro, Propiconazole Pro, Savvi, Spectator, Strider
chlorothalonil + propiconazole**
DMI + nitrile
azoxystrobin + propiconazole
DMI + QoI
triadimefon + trifloxystrobin
mancozeb + myclobutanil**
dithiocarbamate + DMI
Bayleton, Granular Turf Fungicide, Systemic Fungicide
Daconil, Chlorostar, Chlorothalonil, Echo, Legend, Manicure, Pegasus
Fore, 4 Flowable Mancozeb, Dithane, Mancozeb DG, Pentathlon, Protect, Wingman
mancozeb + copper hydroxide**
dithiocarbamate + inorganic
fluoxastrobin + myclobutanil
chlorothalonil + fluoxastrobin**
nitrile + QoI
Disarm, Disarm G
** Not for application to residential lawns.
excellent control when conditions are highly favorable for disease development
good control when disease pressure is high, or excellent control when disease pressure is moderate
good control when disease pressure is moderate, excellent control when disease pressure is low
good control when disease pressure is low
does not provide adequate control under any conditions
cannot be rated due to insufficient data
Rotating and tank-mixing not necessary, but recommended to avoid potential side effects from continuous use of same chemical class.
Rotate to different chemical class after 3-4 applications; tank-mixing not necessary.
Rotate to different chemical class after 2-3 applications; tank-mixing not necessary.
Rotate to different chemical class after 1-2 applications; tank-mixing not necessary.
Rotate to different chemical class after 1-2 applications; tank-mixing with low or moderate risk product recommended.
Rotate to different chemical class after EVERY application; tank-mix with low or moderate risk product for EVERY application.
Continual use of fungicides with similar control mechanisms (modes of action) can result in fungi that are resistant to some chemicals. Poor or ineffective disease control can be expected when this occurs. Managers can reduce the chances of this happening by mixing or alternating fungicides belonging to different chemical classes.
Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data. When more than one brand name exists for an agricultural chemical, the name of brand that first came onto the market is listed first. Otherwise, brand names are listed in alphabetical order. The order in which brand names are given is not an indication of a recommendation or criticism.
Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services does not imply endorsement by North Carolina State University or discrimination against similar products or services not mentioned. Other brand names may be labeled for use on turfgrasses. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county's Cooperative Extension agent.
© North Carolina State University. This information sheet was prepared by Lane P. Tredway, Gail G. Wilkerson, Bridget R. Lassiter, Jenifer J. Reynolds, and Gregory S. Buol. Departments of Plant Pathology and Crop Science, College of Agriculture & Life Sciences, North Carolina State University. Prepared April 4, 2011. Available on-line at www.turffiles.ncsu.edu. This publication was made possible through a grant provided by the Center for Turfgrass Environmental Research & Education (CENTERE) whose purpose is to support worthwhile projects that will benefit both the private sector and the public, and protect the environment.