How to get rid of Poa Trivialis
Before I learned what they were, they had taken over a big area of our side yard, and are very aggressive! I believe it requires a non-selective to get rid of them. If we can't use Roundup, what are the options? And is it too late if they have gone to seed/ are seeding. I don't know how to tell if they are shedding seeds or not.... Thanks!
Montgomery County Maryland
This is poa annua. Here is our page about it. Pay special attention to the conditions that for it: https://extension.umd.edu/hgic/topics/annual-bluegrass This is an annual that you can get ahead of. They are opportunists.
The trick is to change the conditions. Aerate the soil to alleviate compaction it loves. Thicken up your fescue (we don't see hardly any lawn fescue in the photo.) Do that in early fall--late August/early September.
Do a soil test to be sure the pH is right to give your fescue the best conditions you can.
Since you live in Montgomery County, check out their webpages about how to manage a lawn: https://www.montgomerycountymd.gov/lawns/