Wow, I am very aware of the brown spot problem and it has absolutely NOTHING to do with water your St Augustine. It is grubs that are laid in the lawn by the Japanese beetle in the spring. At the end of summer towards fall the grub from the eggs feeds on grass roots. It looks like round brown spots like your dog pissed there. If you pull on the brown spot and it comes up like a patch that's further proof. I treated my back yard and it stopped. I didnt treat the front and it has brown patches and bare spots. Dig around before it gets too cold and you will find grubs......Organic treatment is Milky spore

Been there done that..I hate SA/Florida lawn care....look out for that take all root problem too...if you spot it when it first hits you might be able to reduce the impact....I did the organic thing too...I sprayed Corn Gluten meal on my yard and it really works well...really greened it up...if you spray that in early March it will reduce the weeds for about 8 weeks..but otherwise..it's a great fert. HD used to sell it but not lately...sprinklers and getting water on everything is the key to survival... The fungus will turn your grass yellow/brown..dies....You can toss corn meal on it to prevent or maybe cure it...but I got better results using the commercial fungus cure from Scotts.... You could toss corn meal on your yard a few times a year..I get it at the local ethnic food store...24 dollars for big bag..50 lbs I think... I'm trying a hybrid commercial and organic lawn care now..have to put down commercial weed preventer...that is what killed me before when I went totally organic and the cost of corn gluten meal was way too expensive...now I use the liquid corn gluten meal..found a different supplier...5 gal for 54 dollars via UPS...I get the soybean meal up in Sanford...actually pretty cheap but 50 miles round trip.... I do think in FL we have to put down a lot of fert. If you go organic you will have to use a lot of SBM or Ringers....the rain and sand wash away the nitrogen...also you can toss down Alfalfa pellets too...helps the roots...I get that at Farm city...15 dollars for 50 lbs... Organic is good for results but those darn weeds...difficult to control.... I have a PH of 8.2 which is high but I don't see how I can lower it much...I'm not keen on tossing sulpher on the yard which is recommended way to do it...

After the roots are knit into the soil, once a week watering is far too frequent with temps in the 50s. Depending on the weather, you might not need to water it again until June or July - seriously! Last summer in the Texas Hill Country, it was early July for me. That was a bit of a fluke, but our rains were spaced out nicely. Normally watering frequency depends on air temperature. In Florida it also depends on humidity, which tends to stretch out the watering frequency. As a rule of thumb we water once per week when the temps are above 90 degrees F, once every 2 weeks when temps are above 80, once every 3 weeks with temps above 70, and once a month the rest of the year. The taller you let the grass grow the less water it will need. The reason for that is the roots grow deeper and can get moisture from much more volume of soil. Set your mower to the highest setting and mow every other week until the grass starts growing fast in the spring. Then you might want to mow 2x per week until it slows down again. After it slows down in the spring, you can fertilize.

You picked a doozy of a topic to reference. I don't think I've ever seen so many people piggybacking onto one thread. The spots you see on your grass are the same as those I posted in that other topic. The corn meal should help. Give it 3 full weeks. This is not a shade issue or a watering issue. St Aug will be thinner in the shade but it should be healthy looking with zero spots or yellow blades. Here's a picture of my lawn in San Antonio growing in deeper shade than you had. The point of this picture is 1) no spots, and 2) lots of shade. I took this picture to illustrate chlorosis in St Augustine caused by too much rain. The yellow blades in the center are from the rain. The point you cannot see is that this area looked horrible a month earlier from disease. You could see the soil, leaves, stolons, and spots on the few living blades of grass. Note that you can still see through the turf a little to the stolons underneath. If this was in full sun it would be so packed in the blades would be growing straight up. I'll get a picture of my new lawn in Bandera looking straight down. It's very hard to push a mower through that stuff. Okay I have to comment on the TAMU pamphlet on growing St Augustine. Generally when I see something from TAMU I read it and do the opposite. Truth! Here's my experience this year. I live in Bandera now, so think Texas Hill Country. Our temps ran in the mid to high 90s this year. We got our first rain on Memorial Day and it nearly washed my belongings out of the garage. It was 11 inches in 3 days with most coming the first night. That's too much rain so I was expecting to get some disease. I did but only about 1 square foot was affected. But since Memorial Day I have watering the actual grass one time. Fortunately we got some rain relief last week, so from June 1 to Aug 19 I did not water. Had I followed TAMU I would have watered it every 5 days. Had I followed my own advice (below) I would have watered it every 7 days. What the TAMU people did was over simplify watering, but then they went into too much detail on how to achieve the simple watering. Watering is slightly harder than they suggest but setting it up is easier than they suggest. Here's my take on watering after reading and moderating lawn forums for 10 years. 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. I guess I should add that if it rains 11 inches, reset your calendar back by a month at least. Mowing height. If you read the topic you referenced you saw pix of my dog in the tall grass. (We found her and she's up at the new house in Bandera). From those pictures you can see that tall St Aug is pretty healthy. I seriously did not water, mow, fertilize, or weed that lawn from October 2011 through Feb of 2015. All it got was rainfall. 2011 and 2013 were drought years, and it thrived. Point is keep your st Aug as tall as you can stand it. Set the mower to the highest setting and weld it in place. Contrary to what TAMU says, mowing it low does not make a better turf. Fertilizing. If I was on a rigorous fertilizer schedule I would use organics 5x per year following the federal holiday schedule (Washington's birthday, Memorial Day, 4th of July, Labor Day, and Thanksgiving). If I was on a casual schedule I would fertilize on Memorial Day, Labor Day, and Thanksgiving. If you decide not to use organic fertilizer, I would still strongly suggest you use it at least once a year in addition to, or in lieu of, one of your fertilizer apps. The general experience of the universe of lawn care websites is that lawns that get no organics for 10 years or so will develop issues where the chemical fertilizer seems to not be effective. One dose of organics will reset the soil biology and the chemical fertilizers will work again. I think you can avoid that issue by preempting it. Organic fertilizer is much less expensive per 1,000 square feet than compost. The fertilizer is also much easier to apply than compost.