My wife and I bought our new home two years ago (We live in Portland, OR), which had new sod. The first couple years the lawn was great, then late last summer it started to feel very "spongy" and thatchy. About a month later we started to notice brown "rings" or spots in our yard and the grass became very fragile. I could pull it out with very little effort by just grabbing the blades and giving a light pull. I thought it was grubs, so I applied a grub killer, which didn't help much.
Over the winter the grass has continued to get worse and now is almost completely white, VERY spongy and comes out with almost no effort. I'm hoping I can turn this thing around, but I have no idea where to start. Any help would be GREATLY appreciated.