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June 29, 2018

It is Slime mold time again in central Iowa and I have had several questions on it in the past week.

Wet weather increases the occurance of slime mold in turf.  This problem is caused by primitive fungi that exist primarily as saprophytes (organisms that live on dead organic material) and use living grass plants for support.  Fungi in the genera Muctlaga and Physarium are usually the causal agents.  They can take on a wide variety forms.  Sometimes people describe it as something that looks like the dog threw up on the lawn.  Other times it looks like gray slime on the leaves.  Then, it can take on some truly strange appearances that you would not associate with a fungi.

The fungi can be washed off with a hose.  It will usually go away after the wet dreary weather changes.   We generally do not recommend fungicides for this problem.


I have attached two new pictures from this week.  The first is from Larry Ginger of American Lawn Care in Des Moines.  The second is from Bruno Novotny who works at a course in Forest City.




The others, come from an older post on slime mold (June 4, 2013)






Whats going on in my lawn

August 1, 2018

Many questions have come in over the past couple of weeks about what is going on in people's yards. Many of our previous blogs have covered these topics, so here are links to some of the issues in lawns.  The first issue is due to the wet state to the growing season in some of the state pre-emergence herbicides have not held up as long as typical, also know that applying a crabgrass preventer now will not help. There are some post-emergence herbicides available, but the crabgrass is very mature right now and will take a few applications. If you do have crabgrass please realize that it will die with the first frost, so if you can hang on a while longer it will die in the coming months.  Windmill grass and bremudagrass are also growing with crabgrass, check out this blog on how to identify these warm-season weeds. There are also numerous other weeds that are growing right now, including quackgrass and thistles. Quackgrass is a grassy perennial, and now is a good time to start to eliminate it so you can reseed that area in the fall. Non-selective herbicides work best to try to eliminate quackgrass, and because of the long rhizomes it may take a couple applications to control this grassy weed.

Another issue in many parts of Iowa is a lack of water. Turfgrass needs about an inch of water per week to sustain active growth. Here is a blog from last year on drought and if your yard is dead. Along with drought are several diseases including brown patch, pythium, and summer patch just to name a few of the more prevalent diseases.


Remember that grub damage will start to show up in the next couple of weeks, so keep an eye out for that. If the grass has roots that are gone and the turf just pulls up by the handful it is grub damage. Typically the grubs need to be over 10 per square foot to cause damage.

Good luck and hang in there, better weather is coming for lawns this fall hopefully.


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.