I also have S.A. and live in the St.Pete area so I can relate. I completely agree with giventake about the watering. My front yard has 4 rotor heads and it takes 80mins to apply 3/4in of water. Here are a Few thing that work for me. 1. Mow High (3-4+in) and Frequently with a Sharp Blade 2. Postpone Fertilize and Herbicide Applications 3. Irrigate Uniformly 4. Irrigate Early (between 4-9am) 5. Let Your Lawn Tell You When It Needs Water You'll see spots in the lawn that turn bluish-gray, footprints that remain in the grass long after being made, and many leaf blades folded in half lengthwise. For Florida's sandy soils, 3/4 to 1 inch of water is generally sufficient. Do not water the lawn again until 30 to 50 percent of the lawn shows signs of wilt. There is a simple test you can do to determine how much time it takes to apply 3/4 to 1" of water. (see link below) I put my cans out the night before the sprinklers are set to run then measure in the morning. Here is a link that might be useful: How to Calibrate Your Sprinkler System

I have a sloped back yard around my pool, which is much more steep than your slope in the pictures, covered in St. Augustine. I too detest lawns, but I have no money right now, so my St. Augustine is here to stay. I water my St. Augustine with an irrigation system on my allotted days and once yearly treat with weed/feed. Yes, my St. Aug is great on bare feet and very healthy looking. I have no problems with maintaining it on the slope. I'm not bragging, I'm just trying to explain that I have personal experience with this situation. I think your first problem is with the underlying sand. My underlying soil is a thick layer of decayed organic material, on top of a thin layer of sand, on top of a thick layer of loose clay. It's clear from your photos that the mower tires are disturbing the St. Aug's growth. That is very easy to do regardless of the underlying soil, but especially easy in sand such as you have. I think your second problem is with your lawn guy. Seriously. And, I mean absolutely no offense. Your lawn is covered in weeds. It didn't happen overnight, although sometimes it might seem that way. Your lawn guy should know (1) how to mow on a slope without destroying the roots, (2) how to point out a weed problem before it becomes a massive weed problem like you have. How convenient for him that you need sod replacement?!?! Isn't his job routine lawn care, not routine lawn destroying and replacement? That being said, I have a cheap temporary solution for you. I see in the first picture, to the left of the hose/brick path, you have a bush/tree surrounded by a small circle of mulch. And, in the second picture, you have another tree just down slope from the pool, surrounded by another small circle of mulch. I would take a sharp straight-edged shovel and cut away shovel sized squares of sod in a circular pattern around those trees. Making much, much larger circles around the trees. Take a section of the sandy/weedy area, cover thickly in newspaper, wet newspaper, then lay your homemade sod squares on top of the wet paper. Water daily until they take root and can survive on their own. Go back and extend the mulched area around the two trees, so your weed problem doesn't extend under the trees. This should really be done in stages, because the sod squares that you cut out and move need to be kept wet during the moving process. I say my solution is cheap, because you can buy mulch for $1.68 at the big box stores these days, and you would probably need 10 bags. Less than $20. Of course you will have a little extra water expense from having to water daily to establish the newly sodded sections. It is a little bit back breaking, but I'm sure you can either do it or find someone to help. I say my solution is temporary because, ideally, you could eventually plant some sort of hearty, Florida friendly ground cover over that entire area. In the long run it will not require as much water or care as St. Augustine, and you can get rid of the expensive lawn guy! Things to remember: Don't put any weed and feed down on the newly sodded sections either immediately before or after laying the sod. Don't forget to water daily until the new sections have taken hold. Especially during this, our driest time of year. If you choose to use RoundUp on the weedy areas before moving the grass squares, don't lay the grass squares directly on the area treated with RoundUp unless you put in a layer of newspaper or cardboard first. If you can get your hands on some liriope, you could make a border along the brick walk (at the top of the slope), to help hold it all together. Their roots tend to spread out rather than down, so it will keep slope erosion in better check. Lastly, don't let that man with the mower anywhere near the new section. Weed-whacker only until it's established. You probably won't need to mow this area for the next 6 weeks anyway. Maybe someone else will have a better/easier solution, but this is what I did and it works. I certainly welcome any criticism or comments on my suggestion.

Because it has a fungal disease. Those dark spots on the dead blade are a dead giveaway. Where do you live? What is your watering schedule? How often and for how long?

Okay then good news about the top dressing. It could be so old that it was never graded properly the first time. Or it could be optical illusions. My inlaws in El Monte had a perfectly flat lawn where the soil met the concrete at the driveway and sidewalk with no bulges, so in that respect it was perfect. They didn't water, so it was a mess, but... Yes, dig for grubs just for your own edification. You might find as much as a few per square feet. That's fine up to a dozen per square feet. If you find it squishy with hundreds of grubs, then you should have treated it in July. Treating now is like closing the door after the horses are out. They have stopped feeding for this year. Hot? Okay here's the watering schedule broken down by temperatures. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall. If once every 5 days works in Phoenix at 115 degrees, then 2x per week would never be right for the San Gabriel Valley. It is likely, too, that 1/2 hour is not enough to get an inch. Here's another tip: spray the yard with any clear shampoo at a rate of 3 ounces per 1,000 square feet followed by 1/2 into to 1 inch of irrigation or rain. That will help the soil absorb the water much deeper. j4 is a non-believer in corn meal. I don't know if he's tried it, but it has worked for me every year for the past 14. I have never let my lawn get as bad as your mother's is. It does look dead. I have recovered a dead lawn, but it was from the outside in and required serious patience. Mine was in the Texas (almost) desert and caused by a broken sprinkler system before I moved in. St Aug only spreads when temps are in the 70s, so fixing it in the heat took a little longer than I had hoped. I fixed it with deep and infrequent watering. You might be surprised to see new grass popping up in the middle of the dead. Or not. Just because everyone is mowing short in the area, that won't make mowing short the right thing to do. St Aug will absolutely thrive at 32 inches tall. Here's a picture of my dog walking through my semidesert St Aug. You can see her tail and ears. That grass was never fertilized (or mowed) in the 2.5 years I lived there. When the grass grows up tall it grows deeper roots which can get moisture and nutrients from much deeper in the soil. These roots were in uncharted territory picking up nutrients from way deep down. As it turns out you don't have to water nearly as frequently when the grass is up tall like that. I had one spot that grew up to 32 inches quickly. I never watered that area in 30 months through a full year of drought and then some rains. This hyperinfrequent watering was the point of growing the grass that tall.