# Post Emergent Crabgrass Control Suggestions



## beastcivic (Mar 26, 2018)

Hey everyone,
I've tried searching around before posting, but I didn't see a direct answer to my question, so here it goes:

I handle the herbicide/fertilization at my house and my in-laws home. Both yards were pretty over-run with crabgrass in the past. So, this year I put down 0.37% prodiamine mid-February (roughly 6-7lbs per 1k sq ft). Then about 6 weeks later I followed that up with dithiopyr 40 WSB (5oz over 15k sq ft). Both yards are Fescue.

My yard responded pretty well, I've pulled maybe 100 heads of crabgrass so far this year. Different story at my in-law's house, I spent 3 hours yesterday pulling 200+ heads, and that was only part of their front yard. I cannot pull the entire yard this year (the back yard is more over-run with crabgrass and much bigger square footage than the front yard), but want to kill off the crabgrass before they start seeding to keep the lawn renovation project going.

I'm looking for suggestions, do I get Tenacity, Drive, or Blindside? Do I spot spray or blanket? Or, should I just go the nuclear option and spot spray glyphosate, knowing the fescue will die around the crabgrass and the yard will be half brown for the next 5-7 months. Keep in mind I do want to overseed in the fall, so I need something that won't affect seeding in 6 months.

Thanks in advance for your advice!


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## Suburban Jungle Life (Mar 1, 2018)

Quinclorac with mso or coc?


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## g-man (Jun 15, 2017)

I'm not sure of the weather in Charlotte, but i think it is too early for that much crabgrass. How many tillers? 6 weeks later of dithiopyr was last week, right? Dithiopyr has a post-emergent effect to it too, so it should be controlling it. Could you calculate the ai/acre rate of the products?

Could you post some pictures? Quinclorac (Drive) is the right tool for crabgrass and it should not affect fall seeding.


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## stotea (Jul 31, 2017)

g-man said:


> Quinclorac (Drive) is the right tool for crabgrass and it should not affect fall seeding.


I second this and highly recommend using an MSO (methylated seed oil) surfactant.


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## beastcivic (Mar 26, 2018)

Thanks everyone!

I know it seems early for that much crabgrass, but Charlotte has had some crazy weather this year. We had 2 back-to-back weeks in February with 3+ days of 75-80 degree weather. Then 3 weeks of weather hovering in the 50's-70's, followed by 2 weeks of 60's - 80's. The past couple days have cooled off into the 50's again. But I think the several bumps into the 70-80 degree range (lasting 3-7 days each) kicked off the crabgrass germination.

I'll try to get some pictures, the cooler areas of the lawn (partial shade) have mostly immature crabgrass. But the full sun areas are well into the mature (5+ tiller stage).
I put down the dithiopyr about 10-12 days ago, I'm not sure if that's too soon to see any effect of the application?

AI/Acre of the prodiamine is roughly 1.1 lbs per acre
Dithiopyr was just shy of 0.38 AI/Acre

Looks like I need to get some Quinclorac and MSO to knock it out this season. Will spot spraying it will be sufficient? Or should I blanket spray the entire yard? I'm trying to keep this affordable because it's my in-laws house and they don't exactly have deep pockets.


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## g-man (Jun 15, 2017)

To keep cost down, you could use this: $6 right now at Lowes (until 11Apr2018) It has quinclorac. I prefer to spot spray but sometimes a blanket app is faster.

WBG +Crabgrass


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## Tsmith (Aug 11, 2017)

Are you sure it's crabgrass? I also agree that those numbers seem very high for crabgrass which typically isn't an early spring weed.

Did you spray or spread granules? Crabgrass is the easiest weed to prevent as any pre emergent will prevent it so something doesn't seem right here. Only things I can think of is you either didn't get complete coverage or it's not crabgrass and is actually Annua which is a different animal.


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## beastcivic (Mar 26, 2018)

I've got a 1-gal sprayer, so spot spraying won't be terrible to accomplish. That Weed B Gon product might be easiest (and cheapest). Will the quinclorac percentage be enough potency to kill mature crabgrass?

I'll get a picture of one of the more mature ones. I'm 99% sure it's crabgrass. Especially based on the seed head these things popped up in years past. However, I've been wrong before (maybe it's another crabgrass looking grass? I know I also have a Poa Annua issue as well, but trying to tackle one problem at a time. The Poa is less unsightly than what I think is crabgrass when it puts up that seed head a foot in the air just days after mowing. But again, I'll snap a picture (hopefully later today) and post it up.

The dithiopyr was sprayed (4 gallon backpack sprayer), the prodiamine was put down as a granule.

Thanks everyone for the help so far.


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## beastcivic (Mar 26, 2018)

So here's what I'm fighting. Let me know if I'm wrong about this being crabgrass. These are examples of some medium sized ones in the yard.


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## g-man (Jun 15, 2017)

Hmm, I'm not sure this is crabgrass. It is missing the purple stem.

I'm not sure what it is either. It looks like dalligrass or orchardgrass.

You said it had seed heads, that helps I'd it too. Compare it with this website: https://www.turffiles.ncsu.edu/weeds-in-turf/

Also, in that image there are other weeds. The $6 wbg would still be helpful.


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## social port (Jun 19, 2017)

I was also thinking dallisgrass, especially picture 1.


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## chrisben (Sep 11, 2017)

This weed may be K31 Tall Fescue.
https://www.youtube.com/watch?v=Uj32U9Nbfoo

If so, painting it with a non-selective (kills everything) herbicide like glyphosate (round-up) is the only thing I know that will kill it.
This is one of the clumping types of Fescues that gives fescue a bad name. (although there's a nice looking lawn photo around here that's strictly k31, it takes a bunch of maint to get it there.)

Edit: looked more at the zoom in, I think my vote is dallasgrass too. I think that's a dig it out with a trowel weed.


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## beastcivic (Mar 26, 2018)

Dallisgrass is definitely an option, I just could I sworn the seed head was crabgrass. The seed pods (for lack of a better term) were thin and had multiple forks to the stem. I always thought dalisgrass had those two fat seed pods. 
But either way, sounds like spit spraying glyphosate is my best bet. There's way too many to dig up (we're talking many hundreds at a minimum).
Does the standard pre-emergent work on dallisgrass like it does on crabgrass? Just wondering for next year.


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## thegrassfactor (Apr 12, 2017)

#1 is dallisgrass, can see rolled leaves and pronounced veins 
#2 is orchard grass, can see flat stems


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## beastcivic (Mar 26, 2018)

thegrassfactor said:


> #1 is dallisgrass, can see rolled leaves and pronounced veins
> #2 is orchard grass, can see flat stems


Wow, I was way off. Thanks!


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## 440mag (Jan 29, 2018)

This is a great "grassy Weed ID" (& Solutions) thread. Subscribing!


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