Certainty is no longer labelled for cool season grasses. Compared with Velocity, it is inferior but both leave much to be desired on poa triv control. It may be worth it to try if you are at your wits end and need something to try before a nuclear option is entertained. I personally think early spring selective roundup is the best way. But for poa triv that is young and intermingled with the desirable grasses... no way you can selectively apply roundup. My current experiment is to hit it with Tenacity until it bleaches, then spray primo maxx and follow up with Tenacity. We'll see. I would also urge you to NOT irrigate in the heat of summer. Poa triv is the least heat tolerant of your CRF, PRG, KBG mix. Hopefully much will bow out. Also be on the look out for seeding. If you don't frequently mow or let it grow too long, it will seed and then you have not just stolon spread but a seedbank to contend with.

Despite what I'm being told I am pretty much giving up hope that all these seed heads are coming from my turfgrass. I've been researching poa annua a little bit more and images I see online look very much like what I have going on in my lawn. Here are a few more pictures of my lawn... Opinions? If it is poa annua (I'm convinced that it is), I can't for the life of me figure out why this is happening. My lawn was started from seed in September 2013. I didn't have any poa annua problems in 2014 (nor any of these seed heads). I mow high and I water infrequently. And the kicker is I see nothing like this in any of my neighbors lawns, none of whom take lawncare seriously...so why would it take hold in my thick, high lawn but not in theirs? Was it mixed into the seed the landscaper used but didn't take hold until now? I overseeded last Sept but I know it wasn't in that seed because I had a few bare spots I fixed and those spots are free of these seed heads. And what do I do about it? Kill everything and restart? Keep spraying Tenacity in hopes I beat it? Or, since it's an annual, will it all die this summer, then use preemergents more aggressively?

I try and avoid using roundup unless it's a last resort, and/or lawn renovation; Because of the varying degrees of the half life of Glyphosate. Phosphorous levels have a profound effect on the degradation of Glyphosate. For example, Low Phosphorous contents of European soils decreased the degradation of Glyphosate (Laitinen et al., 2006; 2008; Borggaard and Gimsing, 2008). Another study (Laitinen et al., 2009) showed undecomposed Glyphosate, about 19%, as well as APMA (48%) 20 months after application. Overall, Glyphosate has varying degree of half-lives that depends on numerous things. (de Jonge et al., 2001; Gimsing et al., 2004a, 2004b; Mamy et al., 2005; Sørensen et al., 2006; Gimsing et al., 2007).

most desirable cool season grasses do not like wet and shady conditions. ultimately the conditions will dictate what will grow. you cannot will grass x to grow where the conditions dont favor it over species that love those conditions... at least when no selective herbicides can tip the scales for you. i have an area of wet and shady. i have tried everything. my final solution was to nuke it and sow improved poa triv and white clover. i do not ferilize that area and simply mow it at 3". i dont recommend it to others but it works for me for that particular area of my backyard of approximately 1000 sq ft.