http://www.ipm.ucdavis.edu/PMG/weeds_intro.html maybe someone here has a better eye.

At least for me, the electronic gizmos worked, though we used them indoors to teach our cat to not go upstairs. It was motion triggered and made a noise that was aversive to the cat though we couldn't hear it. A better bet outdoors might be one of the motion-triggered sprinklers since most cats have an aversion to water. Scattering shredded orange peels around the yard perimeter might also help since the scent of citrus isn't something most cats like. Here's a link to the type of sprinkler that I imagine would work well to discourage your visitor. Here is a link that might be useful: scarecrow motion activated sprinkler

I laid sod about three weeks ago in seattle and was told to put starter fertilizer down before hand. You could probably do some after the fact. I watered mine once in the early morning for the first two weeks (it was somewhat warm) and that seemed to be going well. Until the raccoons hit (see post a little farther down if interested). I don't know what part of Seattle you are in, but 6+ raccoons found my yard two weeks after I laid the sod and have done a number on it.

Do not use Medina Soil Activator unless you know for sure you have a magnesium shortage. That product is sold as if it's organic but it's chemicals. You would need a good soil test (Logan Labs, not Texas A&M) to find that out. Just don't do anything with chemicals until you think the problem has stopped. It only needs enough moisture for the sod and the top level of the underlying soil to remain moist. For most people that means to water 3x per day for 5-15 minutes each time. If you have a high flow system, then even 5 minutes might be too much. If it rains and the soil remains moist, you don't need to do anything. It does look like a fungal disease. At this point you need to try to keep it from spreading. Cutting back on watering and letting it dry out a little is the biggest step. My soil prep would have looked like this: Grass Type: Emerald Zoysia Soil prep: no-Tilled possibly Raked depending on how bumpy it looked No extra Topsoil or Compost Leveled with the rake if needed No Insecticide