Tenacity on newly seeded lawn

Kentucky bluegrass, Fescue, Rye and Bent, etc
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nasonjo
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Tenacity on newly seeded lawn

Post by nasonjo » July 22nd, 2020, 8:35 pm

Hey all. First post here. I live in Southern Maine zone 5b and I have been planting about 12,000SF on my property over the summer and it came in great until the summer heat came in. It went from thick and green to overtaken by crabgrass in just one month. I am not sure what I should do. I don’t want to lose all the grass I planted.

I brought in all new loam about 6-8” thick to improve runoff and then seeded it with a mix of TTTF and Creeping Red Fescue along with some Perennial Rye and Annual Rye... I also used a starter fert with weed preventer on it... didn’t seem to help.

I just got my bottle of tenacity in and I am faced with a problem. Do I hit it now (1-2 month old grass mowed 5 times at 4” now height already) or do I wait until a month until late August when I plan to overseed again?

I don’t want the weeds running rampant for the next month but I also don’t want to spray the young grass during the extreme heat of the summer. Do I spray now then again in 4-5 weeks when I’m getting ready to overseed? Would the tenacity stress the newly grown grass out too much? It feels like a lose lose right now but I couldn’t put a whole lawn in during the fall, I have to do it one section at a time. Any advice would be appreciated!
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andy10917
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Re: Tenacity on newly seeded lawn

Post by andy10917 » July 22nd, 2020, 10:05 pm

Maine has extreme heat? You need to get away from the extreme heat to Houston or New Orleans for August - then we'll talk...

You can use Tenacity on the crabgrass, but while it does help, I find it is nowhere near as effective as Quinclorac. And on mature crabgrass, even Quinclorac + MSO isn't perfect. Now you have direct evidence as to why we discourage Spring seedings.

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MorpheusPA
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Re: Tenacity on newly seeded lawn

Post by MorpheusPA » July 23rd, 2020, 11:02 am

With an overseed coming, I might be tempted to simply push the Big Red Button and use Weed B Gon Crabgrass Killer. It'll probably take out some grass (it'll take out some grass would be the takeaway point here), but with an overseed in the works, I'd rather get rid of the crabrass.
Which I wouldn't want seeding out.
Then use Tenacity (or starter with Mesotrione, same thing) at seeding time to suppress sprout of crabgrasses.

schreibdave
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Re: Tenacity on newly seeded lawn

Post by schreibdave » July 23rd, 2020, 12:19 pm

I have been spot spraying my crabgrass with tenacity and I would say that 20% has been killed off, 20% showed whitening and then recovered and 60% showed no ill effects.

nasonjo
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Re: Tenacity on newly seeded lawn

Post by nasonjo » July 23rd, 2020, 3:42 pm

Yeah we have had 90’s with what feels like 100% humidity a lot this summer, which is a bit abnormal.

I know not to plant in the spring but I have way too much yard to plant and I couldn’t do it all in the Fall. Plus the wife was sick of looking at dirt.

I wish I knew that tenacity did nothing before dropping $100 on that and surfactant and dye... of well.

I will use some type of crabgrass killer then.

Should I start now or wait until I overseed? Can I use weed be gone crabgrass killer while seeding? If not how long do I have to wait before seeding?


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ken-n-nancy
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Re: Tenacity on newly seeded lawn

Post by ken-n-nancy » July 23rd, 2020, 5:01 pm

nasonjo wrote:
July 23rd, 2020, 3:42 pm
I wish I knew that tenacity did nothing before dropping $100 on that and surfactant and dye... of well.
It's not that Tenacity does nothing -- there are some things that Tenacity can do that no other "lawn tool" can do. It's just that Tenacity isn't the best tool for eliminating crabgrass from an existing lawn.

As Andy mentioned, quinclorac + methylated seed oil (MSO) is the tool of choice for crabgrass.

For the future, since you have it now, Tenacity is kind of in a class by itself for two common challenges,
  1. be a pre-emergent applied at seed-down of a new lawn to prevent weeds, particularly weedy grasses such as Poa annua and Poa trivialis, which are very hard to control in an established lawn, and
  2. elimination of bentgrass from an existing cool season lawn.
Tenacity has many other uses, but the two above are things it can do that really no other product can do half as well.

On the other hand, for crabgrass removal from an existing lawn, Tenacity is only about half as good as quinclorac + MSO.

KBGkicksazz
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Re: Tenacity on newly seeded lawn

Post by KBGkicksazz » July 25th, 2020, 3:55 pm

I’m going to disagree about Tenacity not wiping out crabgrass on an existing lawn. Ive had Quinclorac fail to kill the mature stuff.

Three apps of Tenacity and it wiped out my crabgrass and by late summer I had a weed free lawn. Spring seeding was my only option that year.

I documented the whole thing here on ATY.

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