I used to live off of Aviation Blvd in Hawthorne. Wish I knew then what I know now. I would have bought every house on the block. My fertilizer recommendation would be ordinary corn meal bought at a feed store, but I realize you are more synthetic oriented. If you were thinking of a chemical fertilizer, I can't help you with names. You can probably use anything that does not say "Weed and feed" but does say "Safe for St Augustine." Weed and feed is a general no-no around here (you didn't ask so I won't get into it). Just buy a St Aug-safe granular fertilizer and you should be okay. If you are interested in an easy, effective, and inexpensive organic program, go to the Organic Gardening forum, find the FAQ, and look for the one on Organic Lawn Care. If you keep the turf irrigated (no more than once a week, but deeply each time) and mowed at your mower's highest setting, your St Augustine will crowd out almost all the grasses and weeds. It will have trouble with clovers, dichondra, dollar weed, oxalis, and some other broadleafed weeds. Those will have to be spot sprayed or hand pulled as soon as you see them. If you pick a spray, be sure it is safe for St Aug. St Augustine should grow and fill a 10 food diameter area each season. A few strategically placed flats of sod should cover a lawn in one season. Most growth is in the spring where it gets summer heat, but 3 miles from the Pacific is pretty mild. You may get growth all summer.

No need for sand. Sand is sometimes used to help level a hole or depression. Try to make your yard as smooth as you can before laying the sod. Make sure the sod has good ground contact. Exposed edges usually die back and take a long time to recover. Putting soil in gaps and around the outer edges of the sod helps sod grow and spread much quicker. Keep it watered well.

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.

That is weird that all over the net nobody recognizes fungal disease in St Aug. The first and last pictures show it crystal clear with the lesions running up and down the brown tipped blades. I have had rousing success fighting fungal disease with ordinary corn meal applied at 20 pounds per 1,000 square feet. Call your local feed stores to check availability. The cost should be well under $10. They might think you want corn gluten meal. You don't. The difference in price will tell you they are selling you the wrong product. CGM sells for roughly $30 per bag. When corn meal decomposes it attracts a fungus which attracts a predatory fungus causing the predator to over populate. Once the initial host fungus is gone, the predator goes after the disease fungus. Your alternative is to use chemicals. I can't help you with that. I've never needed them. But if you use chemicals first, then you cannot come back and try the corn meal later. The chemicals will kill off the predatory fungus from the soil. Try the corn meal first. If, after 3 weeks you don't like the results, either apply the corn meal again or try chemicals. Corn meal was the only thing that worked for me and was good enough to convince me to go full organic with my fertilizer. If you are happy with the corn meal after 3 weeks, you might just use it every month this summer to make sure you got it all. Corn meal is an organic fertilizer, so apply to the entire yard. Otherwise as the grass comes in over the dead areas, it would be much darker green. 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 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.