Forgot to mention, i am in southern ca. Temecula area.

Close up of the lovely brown spots.

And want to confirm what type of grass this is.

Sooo, Temecula means this grass is one of the Marathon blend of fescues, right?

What kind of fertilizer did you use? Chemical or organic?

The weird pattern of death in the second picture may be indicative of one of the Marathon species getting a disease while the others did not. Also the dark green in and among the dead part on that second pic indicates a fungal disease. With that in mind, you need a fungal disease treatment. This time of year, I believe your daytime temps are below 85, so any of the broad spectrum chemical fungal treatments should work. My preference is to use an organic treatment of ordinary corn meal. The best place to get it in Temecula is at the grocery store in the aisle catering to Mexican food. It comes in 25-pound bags. Be SURE you don't get the bags that are tortilla premix. Those have baking powder in them. All you need is plain ground corn. As an alternative to the grocery store, you can try calling the feed store out on 79 at Butterfield Stage, but last time I was there, they didn't have much of anything, nor were they interested in selling actual feed. There's a real feed store in Winchester that was much more helpful in selling real feed. It also helps if you don't look too Anglo when you walk in, there. They didn't realize I speak Spanish and said things about me they would not have said had they known. The application rate for corn is 20 pounds per 1,000 square feet. Give the corn full weeks to see a difference. You should see new grass coming in with no disease and remaining green. If no new grass comes in, but you see the grass at the fringes still coming in green, then you will need to reseed.

You likely need to reseed anyway. In your area you can still do that this year. To do that you'll have to know whether you have Marathon I, II, or III. Get the wrong one and you will have tall or short grass where you don't want it. You cannot remove plugs from the good grass and put them into the dead areas. That will leave holes in your good grass. Fescue does not fill in like, say, bermuda grass does.

If you use a chemical fungicide, follow it up in a month with a light layer of compost to replenish the dead beneficial fungi in your soil. No need to do this if you use corn. The compost app rate is 1 cubic yard per 1,000 square feet. Then sweep it down into the turf with a push broom.

You can fertilize all summer long if you use only organic fertilizer. It looks pretty yellow now, so you might want to get something going. If you use the corn meal on the disease, corn meal is also one of the ingredients in some organic fertilizers. It is considered the lowest protein value along with used coffee grounds (Starbucks is your friend). A better organic fertilizer is alfalfa pellets (rabbit chow) or soybean meal. You can get both of those at either feed store...hopefully. App rate is 20 pounds per 1,000 square feet. You can apply any day, or every day, of the year. If you are going to use a chemical fungicide, I guess I would wait and use an organic fertilizer at the same time as the compost.

Very informative. I appreciate the advice. I will do what you suggested and see what happens. Thank you very much for taking the time to respond.

I am afraid I take issue with dchall's advice. While I agree this appears to be a bad case of fungal disease, it is pointless to use a lawn fungus treatment after the fact. They are meant to be preventive, not curative. The best way to avoid turfgrass fungal diseases is through good cultural practices with proper watering, fertilizing and mowing.

I also dispute the effectiveness of cornmeal as a treatment.The websites that promote it provide anecdotes and no science. I used it myself for a few years, and I think I just wasted a lot of corn meal.

I no longer use any fungal treatment on the lawn. If my cultural practices don't prevent it (and they almost always do), I simply wait for the disease cycle to be finished and then repair as needed. If I were to use a turfgrass "fungicide", I would use a commercial product that has been university tested and I'd save the corn meal for cooking.

To the O.P. -- mow up as much of that as you can and remove the clippings. Verticut, seed, feed, water, water, and water. Then apply better cultural practices next year so this doesn't keep happening.

The link I'm adding is interesting, and it's from WSU Extension. Read it to the end, and you will see why corn meal is not highly touted as a lawncare product by uiniversity researchers.

Here is a link that might be useful: Deconstructing the corn meal myth