Poa Annua Control
You may have noticed this weed in your lawn during the spring months. It is a particularly troubling weed because it responds well to the care you give to your lawn. In the case of a fescue lawn, this weed germinates at the same time you are overseeding your lawn. From there it is happy to benefit from the follow up fertilizer applications that are sure to follow the overseeding effort. You won't notice this weed until late winter into the spring when this weed is at its peak and beginning to produce an abundance of seeds that will germinate in the late summer and early fall. Left to its devices, this weed will be sure to take over your lawn. Especially given that mowing will spread the seeds around.
However, there is good news. Recently, a new control product is now available to quell this weed. It is used in the fall while this weed is becoming established. It is safe to use during the establishment period of fescue plants. It is recommended to be used before your seeding date... even up to the day of seeding. Two timely follow up treatments are needed to complete the process.
Like other new products, I use them on a test basis to make sure I feel confident to approach my customers about using them in their lawns. I had a noticeable poa annua problem in my lawn but not any longer. Last fall I performed this service in some twenty lawns with excellent results. Some had just a small amount of the weed in areas of thin or non existing turf cover. In adequate turf cover, I got excellent control.
In the case of warm season lawns the control efforts are different and easier being that no overseeding takes place. If you overseed your lawn with ryegrass for winter color you should use a perennial rye, not annual rye since there are no label recommendations for annual rye. That means that when your warm season lawn breaks dormancy you will need an application to eliminate the perennial rye.
This is what the NCSU Turffiles website has to say about poa annua:
https://www.turffiles.ncsu.edu/weeds-in-turf/annual-bluegrass/
And some pictures: