Fungus can be both a good and a bad thing.  Mushrooms on pizza are an example of good fungus. Fungus in lawns, on the other hand, are nearer the other end of the spectrum.  If your turf is looking a little thin and brown in spots; you are not alone.  Fungus and hot temperatures will wreak havoc on lawns this year, but there is still time to make your lawn look full and lush for this fall.

With all of the wet weather, mushrooms are popping up in lawns all over.  Do not get overly concerned about these mushrooms.  These fungi are taking advantage of organic matter in the soil and the wet weather.  Once we dry out, they will begin to disappear.  In the meantime, you can remove them from the yard by pulling or knocking over.  They are not edible so don’t consider using them in your next meal.  No fungicide applications are recommended for controlling these occasional mushrooms in the turf.

Dollar spot is a fungal disease that is common in lawns.  This fungus doesn’t discriminate in the type of turf that it infects, but it is most common in Kentucky bluegrass.  The symptoms will be 4-6 inch straw colored patches in the lawn.  The grass blade itself will have a bleached lesion, or spot, with a reddish-brown margin that extends across the grass blade.

There are several practices you can use to deal with dollar spot.  Recommended cultural practices include irrigating in the early morning to remove the dew from the turf and irrigate enough to maintain plant vigor and avoiding drought stress.  Limit the amount of traffic that goes across the turf in the early morning.  Cultural practices can be used to reduce the potential for dollar spot in turf, but in some cases a fungicide treatment may be needed for control.  If fungicides are used, treat the lawn as needed at the first sign of the infection.  There are several products on the market labeled for the treatment of dollar spot, read and follow the label instructions for mixing instructions and reapplication intervals.

Heavy infestations of fungi like summer patch and brown patch is likely in cool season turf like Kentucky bluegrass and tall fescue. The disease cycle of these fungi started in the turf long before the symptoms are visible.  The roots are infected by the fungi in early spring to early summer.  Patch diseases doesn’t have any leaf spots, but the infected plants may have dark brown to black roots. When the hot summer temperatures hit, the roots are not able to take up moisture needed to support the rest of the plant.  The symptoms start out as yellow-tan arcs, rings, or ‘frogeyes’ in the affected turf.  As the season progresses, the yellow turf turns brown. The symptoms are often seen in areas of full sun or in areas that are high stress, like near sidewalks and driveways.  The dead turf will have dark brown to black roots and will secure in the ground, unlike with grubs where the turf will roll up or lift up like a carpet.

Changing cultural practices can decrease the occurrence and severity of the infection.  Turf should be irrigated to maintain plant vigor and avoid drought stress, but avoid over-irrigating.  Maintaining a good fertility program and keeping your mowing height tall, 3-3.5 inches, throughout the entire season will also help decrease the severity.

There is no curative treatment for your lawn once infected.  If your lawn has a history of fungal infections, a preventative fungicide application can be effective, but control of the problem can be patchy.  If you choose to apply a fungicide to control summer patch, applications should be made after the 2 inch soil temperatures reach 65 degrees F in mid-afternoon for 5 consecutive days and repeated a month later.  Applications should be done by professionals for best control.  Focus the applications in the areas that have had problems in the past.

Keeping an eye out for the fungus among us is always a good idea to know the progression of the infection, the timing of the occurrence, and an opportunity to change our cultural practices to help prevent further problems.

 Elizabeth Killinger is the Horticulture Extension Educator with Nebraska Extension in Hall County. For more information contact Elizabeth at elizabeth.killinger@unl.edu, her blog at https://huskerhort.com/, or HuskerHort on Facebook and Twitter.  For more Nebraska Extension science-based horticulture information visit https://communityenvironment.unl.edu/  

Dollar Spot, Brown Patch & Summer Patch, Oh My! (PDF)