I think it is one of two things. It could be brown spot (a fungus) which would come in a green, moist lawn with warm humid weather. The other option is...a dog. Have you noticed a dog in your yard? My front lawn has no spots, but my back lawn (where the Yorkie plays) has brown spots where the grass just pulls right up like you described. Eventually it goes down to bear soil and I either have to overseed or wait for the other grass to fill it in. These spots are right where my dog pees. It's a small dog so the spots are small. You won't have big thick rings around it if your lawn is already pretty green and also if it is a small dog. I hope you kind find out what it is!

Thanks for the input so far. A few other pieces of info. 1) I increased the amount of water (sometimes sequential days, sometimes longer duration) starting about 3 weeks ago when I first noticed the problem (thinking it was not ENOUGH water that was the problem - I'm sure that's a common response). 2) On the edges of the lawn where there is treated lumber edging I've been dowsing the lawn w/ a hose since that seemed to be more yellow a few weeks ago and/or I thought perhaps my Melnor fan sprinkler wasn't hitting the edges enough. Those edges seem very lush and green. 3) On some spots near the Yucca palm I have where I drove in palm food spikes, the lawn is also noticeably greener (circles 8"-12" right where the spikes went in). So I'll experiment a little w/ the watering volume & frequency (less of each, though maybe in a small patch I'll do more.) Will keep apprised.

Ahh. Something I might actually have an answer for.... If the ground around the dead strips is soft and raised then it sounds like you have a Mole or Vole problem. They love to dig tunnels in your lawn looking for good food. A pain in the but they are

My house was on the back of a 1-acre lot on the edge of town. The only tall grass was back by the house, so you had to stop and look kinda hard to see that the grass was that tall. If you were going to be offended, you had to stop and make a big deal out of it. When it's all the same height, it still looks manicured, especially at a distance. Well it turns out there was an ordinance against eyesore lots. The ordinance had words to the effect that you could not have piles of junk with weeds, grass, or plants growing 18 inches high. We all know what this ordinance is there for - so people will not toss their junk on the street and let grass and weeds grow up through it. I did not have piles of junk. I could walk down my street and find at least 5 other houses with piles of trash and weeds growing up through them for 6 months or more. The problem with my house is that it used to belong to a prominent lady in local politics and the church. She was one of those "GET OFF MY LAWN" people who took exceptional pride in the appearance of the yard. She passed away and it went to hell. A guy bought the house to rent the rooms and I bought from him. He let half the lawn die completely. All this happened so fast that the neighbors and friends of the original lady seriously resented my "letting the lawn go." So I was selected for one-time enforcement of the ordinance. I showed up at a city hall meeting and convinced them they needed to print a lot more signs and enforce the rules everywhere in town. They did that and quickly overwhelmed the enforcement employees. I also took issue with the word, plants, in the ordinance. Strict wording of the ordinance would prohibit any plants taller than 18 inches. Everyone has plants taller than that. I started mowing the lawn down to 17 inches to test my skills at passive aggression. A year later they rewrote the ordinance taking the plant/grass/weed height down to 12 inches. So I mowed at 11 inches. Mowing that high takes a string trimmer and actually goes pretty fast - much faster than mowing with a mower. So it was nice for awhile and then not so much fun, but I did learn a lot about lawn care.