In terms of excess moisture, I just poked around a bit this morning on my way to work and noticed that the soil in that area was very wet. I also noticed lots of little bugs flying around that area! Also should add that a couple mushrooms have popped up in other parts of the lawn. With that in mind, I'm thinking a fungus has attacked the KBG and is leaving the fescue plants alone (so far). If you are not watering like the following paragraph describes, you should go there gradually over the next month. 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.

As rifis alluded to, any pink color would likely be red thread. If not, I would guess dollar spot. Neither of which is very concerning. The fine fescue will likely weather it just fine. I do think you are overfertilizing. Fine fescues do better with less fertilization not more. I would also keep cut height long

My bad. You know I did see Houston when I first read the post, but then on second reading I blanked. Sorry for my mini-rant, but we get this a lot. But now I can take care of you. Also I did not see the shoes in the third picture. Unless those are clown shoes or Barbie shoes, it does appear to be St Augustine. Thanks for the watering plan. You are, at this point, ready to change that up...a lot. What you have now is a fungal disease caused by watering too much. Even though this grass is fairly new, you can move to much less frequency and watering much longer. Your weaning time will be short. Watering: Deep and infrequent is the mantra for mature turf. Yours is not quite mature, but it will be in a month as we get some deeper roots. Deep means 1 inch all at one time. Measure that with tuna or cat food cans. Place several around the yard and turn on the sprinklers. Time how long it takes to fill all the cans. If you get runoff, stop watering and wait 15 minutes to let it soak in. Then resume the clock until you fill the cans. That time will be your watering time from now on. But now that I think about this, please wait a week or so before doing this test. You just got a bunch of rain this week, so let that work for you. I got 2 inches and am not planning to watering again until late June (at least). Turn off your sprinklers completely and watch the grass. It should be perfectly fine for at least a week. If you see the blades folding together anywhere in the yard, then do the can test as I described. So what is infrequent watering? This has to do with the air temperature, and in your case, the humidity. For Houston this time of year (and I just checked your forecast) you should be deep watering no more than once every 2 weeks. Mowing: Always mulch mow St Augustine at the mower's highest setting. Always. You can go ahead and weld your wheels in place. Mowing high helps the grass to develop deeper roots which go hand in hand with deeper watering. Those roots will also be pulling nutrients from deeper in the soil. This is really important for St Augustine. Fertilizer: I like organic fertilizer for St Augustine, but I'm not going to drive over and force you. Fertilize it on Memorial Day, Labor Day, and Thanksgiving. I use either alfalfa pellets or corn meal at 20 pounds per 1,000 square feet. As for your current disease, I have had excellent success using ordinary corn meal from the feed store at a rate of 20 pounds per 1,000 square feet. The problem with chemical fungicides in Texas is you are not supposed to use them if the temperature is going to be higher than 85 degrees. Well...that's just about most of the year. Besides, corn meal has worked for me every year since 2002. It is not a problem at all to use it heavier in the areas where the grass is thin. You cannot overuse organic materials on the lawn...unless you bury the grass under them. This is a common problem when using compost. Don't use compost. Where to find a feed store? You very likely do not live in Houston but in a suburb. I don't make a big deal out of the suburbs like I do in the Los Angeles area, because Houston is much more homogeneous than LA. But when it comes to finding a feed store, go to Google Maps and search for "feed stores near (your suburb), TX" without the quotes or parens. Then start making calls to check on availability and pricing. Corn meal is getting cheaper every day. It should be well under $10 for a 50-pound bag. There is another corn product called corn gluten meal. It's a lot more expensive and does not work against the disease, do not let them sell you that. It is an excellent organic fertilizer, but does not work on the disease.

You should check out and do some reading on a place like lawnforum message boards. You don't give us a location. There is cool season grasses and warm season grasses. They behave and are treated somewhat differently. I'm going to assume you are somewhere in cool season grass country (fescues, kentucky blue grass, perennial rye grass). 1) never seed in the spring. The conditions needed to get grass to thrive get weeds to thrive. It can be done. But it's literally worlds easier and you'll have better success doing any seeding in late August into September and possibly early October depending on location. I had to temporarily seed in the spring last year after covid pushed back a yard grading project I had scheduled. It was cheap rye grass that sprouted then died in the summer heat. It was just to get roots down to prevent my yard from washing into the street. 2) never seed in the spring. If you do you'll have baby to infant grass (even when starting as early as possible in the spring) going into summer. The root system isn't well developed and it's certainly not deep and we'll established. Going into the recent above normal summers with infant grass is no recipe for success. You'll more than likely need to irrigate very long and very often to try and limp the immature grass through the heat. Some just won't make it. Additionally, the excessive watering (due to the shallow and underdeveloped root system will leave you vulnerable to fungal diseases) especially turf type tall fescue. Planting in the late summer or early fall gives your grass all fall, winter and spring to grow and develop better roots. It is still vulnerable to summer heat stress and typically takes one or two years for a lawn to root deep enough and hard off enough to be more heat tolerant. 3) unless you are organic only or have a good reason Developed over many years of experience, use a pre emergent in the spring when the soil gets to 50f-55f. The forsythia are typically blooming (bright yellow flowers on unassuming bushes). Assuming you did a spring seed, the heat that is here already in southern nj has my lawn which I seeded last fall already heat stressing since we have had an unusually dry april and may locally here. We typically don't need irrigation until June or so but I needed to run the sprinklers last night, roughly 4 hours a zone to get some deep water into the soil. And that was with me having a picturesque fall seeding with plenty of moisture and nice temps. I wouldn't waste your money reseeding now. By the time the seed germinates in 7-14 days for tttf and 21-28 days for kbg (you could seed with perennial rye and that should come up in 5 but isnt an ideal for most people) the summer heat will be full bore. I'd focus on proper irrigation. Keep why you have alive. Don't fertilize now with any conventional petro fertilizer. If your grass is indeed seeded this spring you may need to get some slow release organic down like espoma or milorganite or similar but not heavy as it'll stress the grass more. I'd also read up on fungal diseases and be watchful of your lawn for signs of fungus. Then when third week of August rolls around you can maybe start making corrections. In the meantime start reading and watching some content online. Fall is the time (assuming you are a cool season turf location) to not only seed but fertilizer heavy and push your lawn so it gets ready for the next spring/summer. You can also use fall to tackle any lingering broadleaf weed issues and if you aren't seeding, allows for another application of pre emergent to help break the cycle of any weeds you may be battling. Some weed grasses like poa annua and poa triv need year round pre emergent to attempt to break their pattern. It's discouraging to see new grass die but it's not uncommon for spring seeded turf to not be ready. It could also have been possible over watering during germination leading to damping off or possibly a fungal infection early on like pythium blight taking out some of those sections. Best of luck.