Wow! I'm glad this came back around. I think everyone has learned something since this thread was started. And now Houzz does notify you when messages you have posted on get more action. So maybe we can tune both of you up at the same time. You should not have to core aerate, ever, with very few exceptions. If you have hard soil there are chemistry reasons and biological reasons for that. The chemistry reason is most often an imbalance in the salts (magnesium, calcium, sodium, and potassium). Those can be addressed with a good soil test. The better lawn forums have been recommending Logan Labs in Ohio for soil testing for the past few years. Their $25 test is what you need. They will email the results to you. If you post them here morpheuspa will give you an extensive reading of the results and get you on your way toward soil perfection. The other reason the soil might be hard and clay-like is biological. There are fungi in the soil that will soften the soil for you once they have been well fed and watered. Spraying the yard with a surfactant will go a long way to allowing water to penetrate the soil and create the environment needed for healthy beneficial fungi. The surfactant can be anything but some are better than others. Ordinary shampoo is a good one. Any clear shampoo, like baby shampoo, will work. Spray the yard at a rate of 3 ounces of shampoo per 1,000 square feet and follow that up with 1/2 inch to 1 inch of water. Allow it 3 weeks to work. If you have other reasons for core aeration, please, lets discuss them. You should also not have to treat for insects unless you have found them in sufficient numbers to treat. The first clue you might have a grub problem is when you see beetles swarming your porch lights in May and June. If you see that then in July, before you see any damage, dig up a square foot of turf down to about 2 inches looking for grubs. If you see fewer than a dozen, then you don't have a grub problem. If you see an uncountable mass of them, then spray. Chinch bugs are more of a southern problem because they like hot soil, but it is possible to see them elsewhere. Spraying insecticide as a preventive measure is not good for the soil biology. Insects are an integral element of healthy soil. Spraying insecticide kills off the bad bugs, but if you don't have bad bugs, then it just kills the beneficial insects. I suspect both of you have watering and mowing height issues. Here's something I wrote a while ago that summarizes what I've learned over the past decade or so. Basics of Lawn Care After reading numerous books and magazines on lawn care, caring for lawns at seven houses in my life, and reading numerous forums where real people write in to discuss their successes and failures, I have decided to side with the real people and dispense with the book and magazine authors. I don't know what star their planet rotates around but it's not mine. With that in mind, here is the collected wisdom of the Internet savvy homeowners and lawn care professionals summarized in a few words. If you follow the advice here you will have conquered at least 50% of all lawn problems. Once you have these three elements mastered, then you can worry about weeds (if you have any), dog spots, and striping your lawn. But if you are not doing these three things, they will be the first three things suggested for you to correct. 1. Watering Water deeply and infrequently. Deeply means at least an inch in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. Do not spread this out and water for 10 minutes every day. If your grass looks dry before the month/week is up, water longer next time. If that does not work, then you might have to water more than once per week during the summer's hottest period. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds. You will have to learn to judge when to water your own lawn. If you live in El Paso your watering will be different than if you live in Vermont. Adjust your watering to your type of grass, temperature, humidity, wind, and soil type. It is worth noting that this technique is used successfully by professionals in Phoenix, so...just sayin.' The other factors make a difference. If you normally water 1 inch per week and you get 1/2 inch of rain, then adjust and water only 1/2 inch that week. 2. Mowing Every week mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. However, bermuda, centipede, and bent grasses will become the most dense when they are mowed at the lowest setting on your mower. In fact there are special mowers that can mow these grasses down to 1/16 inch. Dense grass shades out weeds, keeps the soil cooler, and uses less water than thin grass. Tall grass can feed the deep roots you developed in #1 above. Tall grass does not grow faster than short grass nor does it look shaggy sooner. Once all your grass is at the same height, tall grass just looks plush. 3. Fertilizing Fertilize regularly. I fertilize 5 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above. Follow the directions on the bag and do not overdo it (unless you use organics in which case you may overdo it without fear of hurting anything). At this point you do not have to worry about weed and feed products - remember at this point you are just trying to grow grass, not perfect it. Besides once you are doing these three things correctly, your weed problems should go away without herbicide.

This looks like nutsedge to me also. I have some of it in my newly renovated lawn. I did the RU "glove treatment" on it last weeekend and it's worked pretty well and didn't disturb much of my new grass. I wanted to knock it down prior to the first mowing of my new lawn. If I was the OP, I must considerer the same thing.

That is simply your bermuda grass entering dormancy. I live in middle Tennessee, where it's been pretty frosty the last few weeks. My hybrid bermuda yard is pretty much all brown now, but you should have seen it a few weeks ago. It looked like leopard skin! People were walking by my yard and staring! :-) It's been my experience that both hybrid and common bermuda do this, but the hybrid forms more striking patterns with greater contrast. As an interesting side note, the Celebration bermuda in my back yard is still green. It makes me wonder if Celebration has greater cold tolerance. It certainly demonstrated it has greater drought tolerance this fall when it didn't rain for almost three months.

I see you have a hose and oscillator sprinkler. That's an excellent start. What is your watering schedule? How often and for how long do you water? Did you fertilize yet this spring? Whether you did or not, now is the time to apply for the first time (or second if you did it in the early spring...which you should not have). Have you applied any herbicides or insecticides? If so, when, and what were they? As for your picture, we cannot see a thing at this altitude. You need to be 3 inches away, not 10 feet. And 3 inches needs to be in the shade or have someone cast a shadow where you are photographing. Get a picture with both green and gray grass. Rather than tease you, though, if this is a disease, regardless of which one, I would recommend applying corn meal at 20 pounds per 1,000 square feet. You can get corn meal at a feed store in 50 pound bags for roughly $12 or less this summer. Corn meal is a biological control that seems to work on St Augustine but not on other grasses. Try the corn meal before you try any chemical approach, because the chemicals ruin the biology rendering the corn meal useless as a bio control. Apply to the entire lawn, because you might not realize that the disease has infected the entire lawn. Also do the entire lawn, because corn meal is an organic fertilizer and it will leave deep green spots where you apply, so do the entire lawn. Once you use corn meal to cure St Augustine fungal diseases, you will completely stop worrying about it in the future. It is a complete solution and permanent...until you do something to let it happen again, which I seem to do annually :-( But at least I have a simple, safe, solution. Give the corn meal 3 full weeks to do the job. You will get very anxious about it for 2 weeks thinking nothing is happening. It simply takes 3 weeks, so relax. Between 2 and 3 weeks you will have forgotten about it. Then after about a month you will notice that "suddenly," the yard is perfect and deep green. Also if you are not already doing it, always mulch mow St Augustine at the mower's highest setting. You can let it go 2-3 weeks or longer if your mower can stand it. This will give you a deep rooted grass system that can withstand long periods of heat and go for days without watering. But do, please, tell us about your watering.