Multiple hits of Tenacity looks promising. Still, what looks like dead Poa Triv might actually resurrect itself, so I'm not 100% sure it's completely effective. I am definitely trying to extend the time bleached to see if the control lasts.

I sprayed Tenacity in light applications over the areas of my lawn that are infested with Poa Triv (1x application per week with a very very low application rate) They slowly died off. I then cut out big chunks of the area with some tools (weedeater, etc) down to the topsoil, and I had to spot plant with some KBG/PRG/Peat Moss. I didn't want to take any risks.

Contrary to what people may say, Tenacity on Poa Triv does work, and it seems to have worked very well for me. I used a pump sprayer to spot spray the areas, but I went a little larger, about 6 inches to a foot beyond what I could see with Tenacity.

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).

Thanks for the help, guys. Unfortunately I already put down a pre emergent, so if I try to kill and remove it I'll have to live with a spotty yard until fall when I seed.

I also understand that I can lay a second round of pre emergent in the fall. That's a pretty tight window between seeding and preM app, correct?

I did overseed with KBG last fall. I am holding on to one final slight hope that it's young KBG. I am going to try to snap a few pics for you guys.

Lastly: I am near the end of a soil correction program...I plan on throwing down potash in a few days, then starter fert around memorial day. Should I reconsider?

For me the best time to kill Triv is early spring. It will wake up earlier and grow faster than KBG at this time and you can selectively apply roundup to the leaves. For heavy patches, I will just round it up and hopefully the KBG will fill in by end of fall. Tenacity works best on young Triv. You can identify that was very thin bladed leaves that grow as fast as KBG but intermingled in it. After your first spray with Tenacity, the bleaching will confirm it and you can then reapply Tenacity a few times. Because Tenacity only works if you reapply for a prolonged bleaching effect, you do have to have the discipline to apply it mulitple times.

Thanks so much for the replies, everyone. I just ordered some Tenacity, and I am going to carry on with my soil correction. Prepared to hit it a few times.