Posted the following review a little early. We did get some obvious damage to the truf but still glad we used it. Made our second application yesterday.

This is fabulous! We had completely renovated our lawn 7 years ago and the Nimblewill (Muhlenbergia schreberi) had started to creep back in. If not for the Tenacity we were facing another complete renovation (not fun)! We were careful to avoid the bed edges with desirable plants this year, next year we will spot treat closer to the beds. We know it will be a multiyear project, yet at least we will be making headway instead of watching the Nimblewill smother our grass.

The turf if Turf Type Tall Fescue and has shown no damage with the first application. We have had plenty of rain this summer, so it has not gone dormant. We would probably have watered before the application if the grass was dry.

I had a nimblewill infestation that had consuming 20-30% of my front lawn last year. After it nearly doubled in size, choking out fescue, I decided to spray with Tenacity starting in the spring. It took time to work, but after the 3rd application 3 weeks apart, the nimbleweed is dead - not just white, totally dead and matted. The fescue that got sprayed turned white for a couple weeks but came back to color and was mostly unaffected. I probobly would not have needed two applications If I had a better spray nozzle on the first two. The blades of numblewill are so thin that you need a good surfactant and a very fine mist to coat the blades. If you have larger droplets, it does not stick to the grass as well and I found results to be inconsistent with the same application rate. The lawn looks rough going into summer, but I am very glad to see this stuff is finally dead. I'll re-seed in the summer and likely continue to fight it along the property lines. My neighbor seems to think it's Bermuda grass and convincing him otherwise is a lost cause even as it climbs through his shrubs.

Kills like it should...doesn't work overnight, though. Takes several days to actually see the crabgrass dying. A cautionary note....this kills everything listed on the label..they are not kidding. I had no idea how weedy my lawn was until I used this. The fescues and such were perfectly fine. The weeds? DEAD. The only downside? I really need to plant more grass seed now!
It's pricey, but it really does go a fairly long way. I have an acre or so of "grass" and this bottle easily covers my need

Worked VERY well on late season crabgrass that was taking over my lawn. I applied it WAY after the crabgrass had taken my lawn hostage, so I wasn't expecting excellent results. The label says it is best to get the grass when it is still small. Mine had progressed to tillers several inches long (6-12) when I finally applied the Tenacity. It took 2-3 weeks to see results, but it eventually killed the crabgrass dead, and didn't hurt the rest of the lawn. It takes VERY little product (1 tsp / gal) so despite the price, this bottle should last a long time.

Great for Poa Annua - I planted new sod here in the Pacific Northwest a few years ago and everything was fine the first year. Then coming out of winter the second year I had these small light green patches that i have come to understand is poa annua or Annual Blue grass....a kind of grassy weed. I tried everything, including digging the stuff up and nothing worked. I research the subject to find articles and reports and found this report from Turf Grass Trend tilted poa annua Control from 2012. This report focused on the result of an experiment of applying Tenacity at different time of years under different temperatures and applications rates. The articles finds better results during colder months and temperatures and presents a hypothesis that Tenacity works better the longer that it stays in the plants system and this is best accomplished with two applications two weeks apart in the fall - October. Before I found this article I applied Tenacity from Spring to the fall with limited results. That is the poa annua would turn white, only to return soon after. Finally I applied Tenacity one late winter day when the sun was shinning in February when the temperatures were between 45-50 degrees with rain in the forecast. I bought a new commercial-grade 2-gallon sprayer with a fan-tip and applied Tenacity at a slightly higher rate than recommended two weeks in a row and waited. Within a week the poa annua turned white as normal, however, about 2 weeks later (Or 4 weeks in total from the first application), I noticed bare spots in the lawn - that is the poa annua was dying and not coming back. It's been about two months and things still look good - no poa annua. However, since poa annua is a dormant seed that waits until the perfect conditions - I made another preventive application and will soon replant the bare spots. You can apply Tenacity all year long in the Pacific Northwest - however best results appear to be in late winter when temperatures are between 40-50 degrees where the chemical can stay in the plants system longer due to slow growth. I will update this review - but I think I have cracked the code to control / eradicate POA ANNUA in the Pacific Northwest.

September 2017 update - I re-read the article and it appears that you can also get good control in hot weather as well, but with a different application rate. In hot weather apply half rates a 7 days apart for 2-3 applications will control / kill Poa Annua grass weeds in turf grass. I used this process starting in August, achieved a good kill rate and now I'm beginning the re-seeding process.