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Gray Snow Mold on Turf

March 10, 2021

Gray Snow Mold is a common winter disease that affects a number of cool-season grass species in the northern region.  It is caused by the fungi Typhula incarnata (and a few other species) It occurs during the winter, usually under snow cover.  We generally see circular patches of cottony mycelia six to eight inches in diameter as the snow melts in the spring. 

This year was particularly bad for Gray Snow Mold because of the heavy snow and extended snow cover of turf areas.  There is also a Pink Snow Mold that attacks turf in the winter.  It is caused by fungi in the Microdochium genera.  One of the main, visible differences between the two is that Gray has sclerotia.  These are large, leathery fruiting bodies that appear on the tissue (see below).  Pink does not have sclerotia.

I have had a lot of calls this spring on the snow mold, both from golf course superintendents and lawn care specialist.  On golf greens and fairways, it can cause damage that will be present until as late as June.  For that reason, we generally treat these areas with fungicide in the fall to prevent it.   On golf course roughs and lawns, the damage can be very apparent in the spring as the snow melts, but it usually goes away quickly as the areas come out of dormancy.  Fungicides are very expensive and we generally do not treat lawns and golf course roughs.  In the rough, spring fertilizer and mowing will help to clear these areas.  Once you see the symptoms in the spring, it is too late to apply a fungicide.  This needs to be done in the fall.

If you are in lawn care, explain to your customer that the damage will recover quickly with a little fertilizer, mowing, and warm-weather.  Raking some of the debris away may improve the appearance of the areas, but it is not necessary.

Figure 1.  Circular Patches of mycelia on golf course rough.  Picture by Timothy Christians.

Figure 2.  Close up of mycelia.  Picture by Timothy Christians.

Close up of mycelia.

Figure 3.  Picture of snow mold on Kentucky bluegrass lawn in Des Moines.  Picture by Nicolas May of Trugreen Lawn Care.

Gray Snow Mold on lawn in Des Moines.

Figure 4.  Sclerotia on Kentucky bluegrass.  Pictue by Nick Christians.

Picture of sclerotia on Kentucky bluegrass.  Picture by Nick Christians.


Figure 5.  Close up of sclerotia.  Picture by Nick Christians.

Close up of sclerotia.


Fall Armyworm

August 31, 2021

The past two months I have been watching various social media stories about how bad fall armyworm (Spodoptera frugiperda) pressure is in the states to the south of Iowa. There has been extensive damage in Alabama, Tennessee, Georgia, Kansas, and Missouri to name a few. As time has progressed the damage has moved north into Ohio, Indiana, and Maryland. The fall armyworm caterpillar will devour turfgrass by eating foliage down to the crown. The crown is then left exposed to desicate in warm temperatures. Golf course fairways, athletic fields and home lawns have all been damaged by fall armyworms in these states. On Monday I got the first picutres of egg masses of fall armyworms in Iowa.

We don't regularly see fall armyworms in Iowa, and they arrive with storms and winds from the southern U.S. The southeastern part of the U.S. has seen prolonged damage from multiple genrations of fall armyworms. Storms the past week or so have brought these pests to Iowa. The female moths have seemed to lay the eggs in places such as on the flag and flag stick of a golf course, trash cans, golf carts, and sides of houses. This is not normal. The eggs can hatch in a few days. Many of the young caterpilars will not make it to the turfgrass and will die. If you see the egg masses you can scrape them off with soapy water. Scout for damage and feeding once the eggs have hatched. Blanket applicaitons of insecticide are not recommended, and scouting for damage is best.  

As of writting this blog I have yet to see any of the adults, however there have been some reports of damage from other ISU Extension Specialist. For more information check out this article in Horticulture and Home Pest News.