When you mean fungus, do you mean Dollar Spot (straw colored spots on the lawn, few inches across)? I too am from Michigan and I started organic last year with Soybean meal. Everyone in my neighborhood was affected by Dollar Spot, organic or not. Last year we experienced weather conditions conducive to Dollar Spot - sustained hig humidity day and night, not too hot (burn off fungus), and not cool enough at night to help dry things up. We had about 5 days of this in early July and that started it.
What helps get rid of Dollar Spot is a boost of nitrogen fertilizer. I used composted cow manure. I put that on the affected spots and that gave the grass a nitro boost which helped stop the fungus. This worked much better for me than corn meal.

Yes it was dollar spot, I will try cow manure this time as you suggested. Is this something I can pick up in home depot?

Kind Regards
Dan

Maybe. I found it at a local hardware store. Just make sure its COMPOSTED cow manure and not straight manure. I'm not saying straight manure won't work, but my success was with the composted version. Check with Home Depot, Lowes, Ace, DoItBest, garden center, etc. Its also easier to use, and like most good compost, it doesn't stink.