You can find better pre-emergents at suppliers like John Deere/ Lesco (they've merged) than the home improvement stores. I agree with dchall, in my own findings granular pre-emergents don't perform as well as the liquid. The field testing that that the manufacturers site (so take that with a grain of salt) suggest that they perform about the same. If you're after grassy weeds, such as crabgrass, dimension is a great pre-em. If you're seeing a lot of both grassy and broadleaf, Prodiamine is a good alternative. The advantage with Prodiamine is that it is much cheaper to manufacture and has a number of generic versions. The 2-4D that Dchall mentioned is definitely a safe alternative in cool-season grasses for broadleaf weeds. Another, if you have trouble with crabgrass this season is Quinclorac. Quinclorac has the major advantage of being safe on Fescue even when it has just been seeded. To my knowledge it is the only herbicide that can boast that. If you mix it with a methylated seed oil, you have a good crabgrass control. The only odd exception is crabgrass that is in the intermediate stage, between newly emerged and mature quinclorac won't give any control during this period. As for the bright green grass, it isn't uncommon when you've been seeding so see color differences. Tiemco is correct about KBG being a dark green when it matures. There is a definite possibility that what you've seeded has come up much darker than what was there before. I ran across this today with a Fescue lawn that I seeded last Fall. The cheaper Fescue that was in the lawn looked much brighter than the cultivars that I used which included Speedway, Davinci and Blackwatch. So it's entirely possible, that the brighter colored grass was a lower quality Fescue, such as K31 that was there before. All the same, make sure that you don't over-do the seeding, which can lead to over-crowding and cause die-back or pythium blight in the up-coming months. Also, it's good to use a blend. There are a number of improved varieties of both bluegrass and fescue on the market today, which offer advantages over the older cultivars. For example, you can buy a mix of thermal blue, which is 10% bluegrass and the other 90% is made up of 3 different Fescue cultivars. It's highly drought tolerant and disease resistant. Either way, good luck and thanks for sharpening our skills with your question.

Poa triv is pretty tough stuff, some even say Round-up won't kill it for good. It seems to come back the next year after that. Even if you get rid of it, then you will be left with bare patches. Some people have had success using Certainty, but I am pretty sure that will harm fescues. Seems like the only real fix is removing the top two inches of turf to get rid of the roots and stolons of triv, and start those areas over again.

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.

Thanks kimmq fall is coming around soon and hopefully the temp cools down it’s been hot here lately and I’m worried all the work I put into the lawn is going to waste