I’ve added these pictures of the lawn problem. I hope this helps. Sorry I didn’t realize how to downsize the image until after I sent the first inquiry. Thank you. 

Hello Sue,

Thank you for entrusting your lawn care questions to us.

Fungus diseases in lawns are difficult to positively diagnose without lab tests. And once the humidity and temperature are favorable, the fungus spores that have overwintered in the soil can spread rapidly. The last week to 10 days have been perfect for the growth of lawn fungus disease.

The photos you shared help confirm that it is likely a fungus, but to determine which specific fungus, we need close-ups of the blades to look at the lesions. Even with close-up photos, experts can disagree about what the fungal disease is.

There are general cultural care recommendations that can limit the damage of a fungal infection. You can add a light dose of nitrogen fertilizer. Also, when watering, make sure you water early in the day so that the grass blades are dry by dark. Some fungus attacks when the grass is stressed, and some added nutrition can help fend off the pathogen. Fungicides are generally the defense against fungal infections, but there are limitations with them as well: Fungicide effectiveness is fungus strain dependent. By the time you see the damage it is essentially too late to treat with a fungicide. The damage has occurred in the weeks to a month preceding. Even when the appropriate fungicide is applied at the appropriate time, they are not 100% effective.

My thought is that the patterns you shared are consistent with Fungal Patch Disease. But the only way to confirm that is lab testing. Take a sample at a margin so that you have the dead grass, the dying margin and good grass all in the sample. Send this sample to the MSU Diagnostic lab to have the type of grass and the type of fungus identified. The services and cost structure for MSU Diagnostic Services can be found at:

https://www.canr.msu.edu/pestid/ Tips on how to take a good sample can be found at:

https://www.canr.msu.edu/pestid/submit-samples/

The results from the lab will positively identify the fungus, so you know what fungicides you should apply and when they should be applied. It will also identify the type of grass, because maybe you can grow a different cultivar that is less susceptible to your type of fungus. Then finally, the soil test will give you specifics about pH and nutrients so that you can optimize your cultural practices.

Once you get your results from the MSU Diagnostic Lab, feel free to answer with the results, so that we can suggest a treatment plan.