Every year brings at least one or two weeds that have a “banner year”. Last spring it was Orchard grass. This years spring winner is definitely Poa Trivialis in tall fescue lawns! Poa Triv is a PERENNIAL meadow bluegrass. It is claimed that it was introduced in the USA in1800s, but who really knows. I counted over 20 states that have some. It germinates really nice during fall aeration and overseeding. The question I am often asked is, was that in your seed blend in the fall? The answer I got from label says no! Poa Triv seed can lay dormant in your soil for years! When conditions are favorable, BAM! You get some! It spreads by stolons(above ground stems). During mid March through mid April, it grows faster than any cool season grass! Its crappy yellow color is genetic! Therefore, when you mow your fescue, the Poa Triv gets scalped because it grows 2x faster than the tall fescue. That leaves you a “nice” high yellow spot with a scalped white stem look as a kicker! The good news, as air temps climb into 80s, its growth almost stops! By June, the leaves turn brown and it looks like its dead! You can no longer find it by July! What sucks is, the stolons and crown survive the heat with irrigation and broken sunlight. Since you can’t see it, you can’t kill it! There is nothing I have tried that kills it without killing fescue in spring. So, I am telling you to “live with it”! I promise by May, you will be more concerned with nutsedge!