I wouldn't use apply anymore nematodes and generally there is no reason to apply any grub treatment unless you can actually see the beasts in your soil.

Summer patch is a tough one. Re-seeding is the cheapest way to deal with it, but you'll be doing a lot of it.

I question whether it's a fungus. Unless you're really overwatering, you shouldn't get hit with fungus in Utah. It's just too dry. And if you're overwatering, the fungus would probably be more widespread.

The parking strips can get hot pretty easily and they're also harder to get the sprinklers adjusted to spray enough water on them. I think it's more likely that the parking strip is drying out faster than the surrounding area. You could also have stuff under the surface so that there's not much soil for the grass to root in.

After watering the next time, stick a screwdriver in the soil in that area and see how far you can get easily get the screwdriver to go in. I'll bet it doesn't get very far, which will mean either that you're not getting enough water there or that there's something under the surface.

I also live in SLC and have south-facing parking strips similar to yours. I gave up trying to grow grass on mine because the underlying soil was so poor, they dry out so fast in the summer heat, and were a pita to mow.

I killed the existing grass, installed a drip irrigation system and some bubbling sprinkler heads, mulched to retain water in the soil, and planted Blue-chip junipers and St. John's Wort groundcover. The junipers and groundcover seem to thrive in the poor soil with very little water (relative to thirsty bluegrass) and require no maintenance other than a little pruning a couple times per year.

Just an idea if you aren't attached to the idea of having grass growing in your parking strips.

Great great great suggestion above. I couldn't say if this was the OP's problem or not but generally speaking a great many lawn issues people have really amount to nothing more than trying to grow grass where it doesn't want to be. It's heretical to say I know but the less lawn you've got the better. Less turf and more landscape.

There might be another reason. How old is the house?

It turns out that the issue seems to be that area wasn't getting enough water. I started spot watering and it greened up a lot better. There's still some bare spots but they are much smaller now. I no longer think this was summer patch just poor sprinkler design.

Regarding the age of the house it was built in 1904.

Glad that you figured out your problem. The reason I asked the age of your house relates to newer construction and sloppy workers who toss paint thinners and whatever around during construction. It is quite common to have a spot or two just outside the entrance/garage doors where nothing will grow because the soil has been rendered sterile by some unknown dumped there. Also, in those states that still allow open burning the workers very often set up a metal barrel and burn wood scraps for months. This can cause a frustrating sterile spot, usually in the middle of the lawn you are trying to grow.