Try again with the picture.

Twice the web site rejected the picture. I've reduced the file size. Maybe it will work this time.

That darker grass has thicker courser foliage, you likely have some patches of another species of grass among your fescue. Now, you could spot spray and later reseed these areas, this is what I do, as I have the same problem.

Thank you FrozeBudd_z4 for your comment about similar experience and suggestion. To me the coarser grass looks like Kentucky 31. My lawn was sodded five years ago when the house was new. I’m no expert but I think that turf grass tall fescues, like my sod, are mostly cultivars of Kentucky 31. I was thinking of doing as you suggested but hesitated because I do not know for sure what caused the spots to die in the first place. I have been thinking either (1) urine from dogs or other visiting animals, or (2) fungus. If urine, then the spots would be high in nitrogen. In this case, perhaps the “Kentucky 31” was best able to thrive in this condition. It is dark green, a sign of high nitrogen. On the other hand, if the original grass was killed by a fungus, would reseeding be expected to work without first using fungicide? I’m inclined to follow your suggestion to kill and reseed, but would be more comfortable if I knew exactly what is occurring.

Interesting ... okay, I was gonna say that the die out areas could be caused by dog urine and the dark green simply being a consequence of the higher nitrogen in the immediate area ... but, those those dark grass blades do look wider and as you say resemble blue grass. You might have a fescue / blue grass lawn and the latter being a bit more resistant to dog urine. If simply caused by dog pee, the bald area will fill in by themselves and the dark green will subside in time.

I notice the grass along the asphalt being lighter in color, has the weather been hot and dry?

Summer here has not been unusually hot, but during a dry spell, the edges next to the asphalt road and driveway are the first to dry up and go dormant. I'm retired so I can keep an eye on it. When the edges start to go, I irrigate them with the hose. Re the fungus vs. dog pee question, I may just buy a nitrate test kit and compare the spot with its surround. Kentucky 31 is actually a fescue, not blue grass. It is a very rugged, physical abuse and drought tolerant grass but is a bit lacking in aesthetics.

I have the same issue in my Kentucky 31 only I have Bermuda grass coming up in the middle of my patches.

The man who takes care of Main Street and the Court House lawns told me to over seed with perennial rye this fall. That is what he does and those lawns are beautiful !

I will spot spray also

Good idea to rule out the fungus verses dog pee issue, that'll help point you in the best direction as for correcting the matter. I had a fescue lawn at my previous residence, nice enough, though drying to a crisp most summers. Now, my blue grass turf also does the same, though mostly only where the soil is the poorest and driest. I had been thinking of planting one of the new drought tolerant blends, though a friend had done so and her turf is tooo course for my liking, though there likely exists superior blends.

I think cutting your grass so that it's a bit on the long side may help in dry conditions. It seems to work with my lawn. As I understand it, leaving it longer encourages deeper root growth and better drought tolerance. I started leaving my grass longer when I saw that my ground surface is uneven. Having a too-wide mower deck doesn't help either. If I cut my grass at, say 3", some of it ends up scalped.

You know, I was indeed thinking the same today, that I tend to cut my lawn tooo short, so up will now go the mower deck! I also must get around to having the grass sprayed for dandelions and whatnot. I have a very large acreage yard and worked hard to obtain a good looking high quality lawn and starting from the ground up with a thickly forested lot .... BUT, darn for those lawn weeds and nasty poa that seeds out everywhere with a vengence!