A healthy vigorous stand of turf grass will keep most of the poa anna out. First make sure that the weed is poa anna, and not a perennial cool season grass. Poa anna will not usually make it through the summer in your area. However, you must fix the underlying problems to keep the poa anna out of your yard. Does the bermuda get enough nitrogen fertilization at least a couple of pounds of nitrogen per 1000 square feet during the growing season. You said that the problem side of your yard has a lot of shade are tree roots also competing for water in this area? Also, bermuda grass needs at least 6 to 8 hours of direct sun a day. If that can not be achieved then maybe you need a more shade tolerant turf, such as zoysia, to be able to compete with the poa anna. If the area stays wet it might also be highly compacted so aerifiying during the summer would be a good idea. If some or all of these problems can't be corrected then you should just live with the poa anna because once you get rid of the poa anna another weed will take it's place if you don't have a healthy turf grass to fill in the area that the poa anna occupied. Eradicating the winter annuals from bermuda (poa anna, chickweed, and henbit) and keeping it out is not a difficult task.You can spray Roundup, buy the concentrate that contains just glyphosate and spray at the low rate, on your dormant bermuda grass at the end of January beginning of February.This is not as scary as it sounds just make sure you don't have any green tissue in the leaves, stems, and stolons. Maybe start small and just spray a couple of spots this year and see how it turns out. As for the henbit and chickweed, Bayer has a broadleaf product with 2,4-D, dimethylamine salt/ Mecoprop-p, dimethylamine salt/ Dicamba, dimethylamine salt. Spray this product mid/late spring when air temps are over 50 degrees. Pendimethalin is the best pre emergent option for the home owner, to keep out poa anna. Pendimethalin is sold as Halts by Scotts. Follow the labeled rate and apply around August 15th water in immediately with half an inch of water. Pendimethalin will also take care of your henbit and chickweed as well.

I need to know why you say that, formicburn. I put down Halts. Then, because my lawn didn't come back, I aerated the snot out of the yard (really chewed it up) and put down seed. I ran the aerator, then put down seed, then repeated the process several times. No new dirt, however. Nothing so far. I ask because I am now contemplating putting down sod. Not challenging at all. I don't know squat. Just wondering if there is still hope that the new seeds will germinate when - whenever that will be - it gets warmer. Thanks

Just moved into this house a little over a year ago so late spring I put down some weed n feed then late summer I put down some fertilizer can't remember the numbers but just nitrogen X-0-0. Controlled most of the Sandburs but by the end of the year I had some coming in in a few spots. Water at least once a week deep (sandy soil) with well water. Last year I mowed at around 2 1/2 - 3" going to see if I can do 1 1/2 or 2" this year( not the smoothest of yards but working on it). I only bag the first time after that I mulch. I attached a photo and the area in green is my main yard I want it to look as best as possible, area in red is what I keep mowed but it is relying on rain for its water. Blue is my property and cows take care of what I don't mow. Ramping up my operations this year I built a tow behind sprayer so I can't try to keep everything in red looking good. Blue area is around 9 1/2 acres

Crabgrass is a summer annual plant that only returns by seed the following spring. It has a quick-germinating seed, so if you try to establish grass in the spring, the first seedlings you see will almost always be crabgrass. Then if you think the new crabgrass sprouts are your target grass seed coming up, there is a tendency to stop the daily watering. Once you do that the target grass seed just sits there while the crabgrass fills in. It is adapted to heat, low mowing, and dry spells. It's also yellow and shaggy compared to more popular turf grasses. The best way to avoid getting crabgrass is to create a dense turf to begin with. The best way to do that is to make it dense in the fall after the crabgrass has stopped germinating seed. You can kill it out to create open space, seed into the open space, and the new grass will provide that density that keeps the spring weeds out. If you start early in the fall (in northern Utah that means August), then you will have time for the new seed to come in and still reseed if it was not dense enough. Continuing with the best way to keep crabgrass out, if you can withhold water in the spring and keep to a temperature driven watering schedule, that will deprive the summer annual weed seeds from the continual moisture they need to germinate. And the last thing you need is to provide as much shade on the ground as possible. Do that by mowing the grass at the mower's highest setting. Beyond those cultural practices you can use preemergent herbicide as has been discussed. Ideally you will develop a turf that is dense enough that you won't get crabgrass. I have not had crabgrass in forever with a dense St Augustine lawn. 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.