There is nothing fun about fungi

Well, if you are into microbiology (which I am) then fungi is fun.  The names are fun... Bipolaris sorokiniana and Drechslera poae and Leptosphaeria korrae. See?  Those are fun to say. And I love how they work, act, spread and multiply... it's incredible to watch under microscopic cameras. Unfortunately the effects they have on a beautiful expanse of green grass is NOT.   Here is some information I found for you about a few common grass fungi on gardeningknowhow.com  

Melting Out   - This grass fungus is caused by Drechslera poae. It is frequently associated with Leaf Spot because a lawn affected by leaf spot will be highly susceptible to Melting Out. This lawn disease starts out as brown spots on the grass blades that move rapidly down to the crown. Once they reach the crown, the grass will begin to die in small brown patches that will continue to grow in size as the fungus progresses. This disease commonly appears in lawns with major thatch presence.
Melting Out grass fungus treatment is to dethatch the lawn and apply a grass fungus spray to the lawn as soon as the disease is spotted, the earlier, the better. Proper lawn care will help prevent this lawn disease from appearing in the first place.

Necrotic Ring Spot -   This grass fungus is caused by Leptosphaeria korrae. This fungus is most likely to appear in the spring or fall. The lawn will start to get reddish-brown rings and you will be able to see black “threads” on the crown of the grass.
Necrotic Ring Spot grass fungus treatment is to dethatch the lawn vigorously. As with Melting Out, the thatch is how the fungus spreads. You can try adding a fungicide as well, but it will not help without dethatching regularly. Also, lower the amount of nitrogen fertilizer that you give the lawn. Even with dethatching and proper care, it may take up to two years for this lawn disease to come under control.
 
Dollar spot is caused by the fungal pathogen Sclerotinia homoeocarpa, in the Sclerotiniaceae family. The pathogen blights leaf tissues but does not affect turf grass roots or crowns. The disease is a common concern on golf course turf, but is rare in sports turf and professional landscapes. Disease symptoms commonly result in poor turf quality and appearance.  The disease occurs from early spring through late fall, but is most active under conditions of high humidity and warm daytime temperatures 59–86 °F (15–30 °C) and cool nights in the spring, early summer and fall. The disease infects by producing a mycelium, which can be spread mechanically from one area to another.

So the effects are not nearly as much fun as the names.  Yes yes. I AM a science geek.  I find it all fascinating (way more fun than bugs! Blech!) But really, the first step in waging a war on something, whether it’s fungus or bugs or weeds is to know how it works.  Then you can find a chink in the armor and go for the weak spots!  Yes, I’ve also read way too many medieval times novels! But you get my drift right??  Here’s a picture of the Bayer product.  It comes in a liquid concentrate - you attach your hose to the bottle and spray away - or in a granule that you spread the same way you would dry fertilizer or grass seed.  For a happy lawn, detatch, wash you mower and tools and use a fungicidal product. Good luck!