SyngentaTenacity Herbicide, Pre-Emergent and Post-Emergent Weed Control, Liquid Weed Killer for Lawns and Turf Grasses, Active Ingredient Mesotrione Herbicide - 8-Ounce Bottle

I will share my experience with this product since there is not alot of scattered information regarding it, and I had to piece together information before using it. I have your typical Bluegrass, Fescue, Ryegrass lawn that is common here in the midwest. I noticed that my weed population (creeping charly, clover, knotweed, splurge) kept increasing despite my endless efforts to irradicate them. It wasn't until I started to rake the lawn that I realized I have an intruder that was creeping OVER the top of my existing lawn, and in a lot of cases it was intangled thru the existing grass. Raking had exposed the extreme difference in growth pattern, and there was an obvious difference in the length since it was growing from the center out. Once raked, it was like wiry arms waving hello above the regular grass! It was killing my good grass, making it sparse, and allowing these other weeds to invade. It forms a mat, so it was also trapping moisture underneath- creating lawn fungus for the good grass!I researched extensively, and found that I had nimbleweed and bentgrass. Ugh!Despite the price, I chose to use Tenacity and save the good grass.You have to be patient with this product, it does work, and despite it working slow, it is powerful stuff, so follow the directions since they are specific to the weed you are applying them too. For Bentgrass and Nimbleweed you want to apply 3 weaker applications instead of 2 stronger ones due to the aggressive stolons that bentgrass produces. After about 10 days you will start to see the nimbleweed and bentgrass dying back. It becomes more apparent after the 2nd application. It did cause whitening on my fescue, which does recover, and it did a little damage to my rye.I lived in fear for weeks worried that this stuff was gonna kill my whole lawn, but it didnt. It did reveal to me that I had much more Bentgrass than I had originally suspected (apprx 70% of my lawn). Once all the intruders were dead, I bought a good dethatching rake, and highly recommend one if you have areas that are thick with dead bentgrass. In the areas where the amount of dead bentgrass is thinner, you can just leave it and the regular grass should grow back thru.A bonus to this product, is you can overseed right after your very last application, and your new seedlings will not have to compete with weed seeds when trying to establish. Since this product kills alot of other weeds in the process, I have less weeds in my yard than I have ever had. My pre-existing lawn also seems healthier now, since it is not competing with the bentgrass and nimbleweed for sunlight, water, and nutrients. I did overseed the bare areas and have a new thick beautiful lawn coming in. I have no regrets using Tenacity, and will do a follow up application in the spring to hit any missed stolens that might still exist.Some recommendations- The product comes with a syringe so you can extract the chemical directly out of the bottle. Though I appreciated it being included, I found it difficult to use being the bottle is small, and I almost spilled it a couple of times due to the mechanics. Maybe try a measuring spoon instead. In order for this product to work, you MUST apply it with surfactant. I used Bonide Turbo Spreader Sticker (bought from Amazon also) and was pleased with the results. You can also mix Tenacity with a other chemicals listed in the instructions, so I mixed Triclopyr in the 1st application to help irradicate the creeping charlie. I would be hesitant to use this product in mid-summer when it is extremely hot, only because our cool season grass in the midwest is already struggling during that time. I waited til mid/late August when the temps would start to drop. Do not spray this on any other plants or trees, it will hurt them, and possible kill them.My only regret is that I wish I would have found this stuff sooner! I hope this post helps anyone trying to battle nimbleweed or bentgrass.

I have been trying for some years to identify and control the undesirable lawn grass called nimblewill. I thought it was Bermuda grass, which is similar, but it is somewhat different.The nimblewill has been slowly and consistently spreading and taking over my lawn for a number of years. It probably had taken about 20% of the lawn (about 0.7 acre lot). I thought it was pretty much hopeless. None of the lawn weed killers or crabgrass killers that don't harm the desirable grass will phase it. I thought I would have to roundup huge areas or most of the yard to get rid of it.The Tenacity is expensive, $60 or so for 8 oz. But for the number of gallons it makes (you use a syringe to measure it out, and it only takes about 1/2 teaspoon per gallon), it's really not that much more expensive than any other lawn herbicides or general vegetation killers for that matter. I have mixed and sprayed 22 gallons of the Tenacity, 2 gallons at a time, and I have only used about 1/3 of the bottle. I also used a surfactant, which is relatively any expensive and is supposed to increase the effectiveness. The Tenacity is a tanish, milky liquid. You don't want to get it on you. I was careful not to, but if I got just a minute drop of overspray on the skin, I could feel it burn.Anyway, I walked around and sprayed the all the visible nimblewill in various sections of the lawn 2 or 3 times during late June and early July, when it was actively growing in the hot weather. It was a little slow and time consuming, but it was effective, and I didn't waste the tenacity or over apply it. I tried to do it when it wasn't too hot or dry or right before rain, although I don't know if that matters . Anyway I walked around and hit the nimblewill in the all the different areas of the lawn at least once, maybe hit some bad places a second time. I sprayed some big patches, and many more isolated clumps where it was just starting to spread among the other grass. It is relatively easy to spot even when it is green and growing. It is blueish, low growing, and the grass leaves are flat and up to about 1/8" wide. I had no trouble spotting it among the desirable grasses when I was walking around spraying.At least 3-4 days after spraying, the leaves of the nimbewill grass start to turn white on the ends, then the whole upper grass leaf will turn white. Kind of unusual. It stays that way for a while. It stops growing and eventually it turns brown and dries up, but it takes several weeks for the whole kill process to complete, even in hot, relatively dry weather. But you can see results pretty soon, and continued results over time, and it's gratifying.It's hard to say if the other desirable grasses were harmed significantly or not, because it has been very hot and relatively dry. There is no obvious evidence of it, but some of the nimblewill patches were thick, meaning big brown spots, and some of the rest of the grass is turning brown anyway now due to heat and lack of moisture this summer, which is a little worse than normal. I plan to slit seed the whole yard closer to fall, so I don't really care if I lose a bit of desirable grasses to collateral damage or not. I am gratified just to see very little living and actively growing nimblewill at this point.Anyway, at this time or the summer, when it is usually thriving and will soon go to seed, I have very little green nimblewill in my lawn. I plan to make another pass or two soon and hit any more that I see that is still green.Bottom line with about 1/2 of a 8 oz. bottle this summer I realistically expect I will kill at least 85-90% of huge nimblewill infestation in a 0.7 acre lot. I will have plenty of Tenacity left to spot treat any I see for the next couple of years, and I expect to see a lot less each year. I have hopes of essentially eradicating it. They don't claim this is possible and say you can only "control" it, but I think with some diligence you can eradicate it for practical purposes.I also learned that the Crabgrass and weed preventers that are applied in the early spring help control nimblewill and keep it from spreading from seed. I had stop using these crabgrass preventers several years back because I had the crabgrass under control in my lawn. Not a good idea, because I think that helped allow the nimbelwill to spread uncontrolled and infest the lawn. Nimblewill goes to seed in the hottest, driest part of the late summer when you aren't mowing often. So you inadvertently allow the seeds to form and spread before they are mowed down. But I started using the crabgrass preventer again this spring, mainly to help control the spread of the nimblewill via seed, and I plan to continue using it as part of my efforts.

Great product. Wish I came across this many years ago to solve my lawn maintenance woes. Scott's Tall Fescue seeding introduces so many varieties of weeds, is unbelievable. I have always struggled to address until now. I can now have a totally weedfree lawn going forward when I seed again in the Fall. This is just my preliminary review after one week of application. I am giving 4-stars now because it's so promising. I recommend Tenacity.