# Did a chemical burndown, but this grass wouldn't die. What is it???



## LsHay (Nov 4, 2020)

The burndown (Roundup, dicamba, 2, 4-d on July 21) stunted it but didn't kill it (last photo). It's also in my lawn (first photo), and the photo with sky is to show the seedhead.

What is it and how do I kill it???


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## blakjak (Aug 4, 2021)

Middle pic is a bit out of focus but could be redtop?


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## broadriverhay (Jun 13, 2014)

Could it be Vassey Grass ?


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## broadriverhay (Jun 13, 2014)

I’m sure Weedman will chime in and give some advice. No need for me to express my ignorance when he can get it all correct the first time.


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## weedman (Jul 12, 2019)

It is hard to tell from the pic of the seedhead. If you can grab a pic or two in better lighting I can probably tell you for sure. Right off hand, I’d say it looks like a Tridens species (ours down south I called purpletop), but the foliage doesn’t look quite right. Post up additional pics and we shall see.


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## LsHay (Nov 4, 2020)

Well, folks, it's been an interesting day. Turns out those are photos of two different weeds. My first clue was when I dug up the roots and they were not the same. The nice green one with the lovely purple seedhead (in the lawn, not sprayed) appears to be greasegrass which has nice, simple roots. I didn't find it in the burndown residue to I guess the herbicide killed whatever greasegrass might have been in the field.

The one that was sprayed but not killed appears to be beaked panic grass (panicum anceps).

The beaked panic grass had roots with rhizomes. It also had a different color seedhead but I put that down to the herbicide changing the color as the plant died.

Now, how to kill it? I'm told it takes a non-specific herbicide like... glyphosate! Been there, done that, it didn't kill it, now what? The local extension agent who helped me identify these two weeds suggested trying paraquat or another round of glyphosate. He said beaked panic grass is not known to be resistant to glyphosate but because of their extensive rhizome network, they can pull additional self-sustaining nutrients from one plant to another.

So at this point, I'm not sure how to proceed. Would a stronger concentration of glyphosate knock it out? Additionally, there is some nice, new dogbane popping up through the residue, the horsenettle was not completely killed first time around, and there are a few milkweed plants (which I thought I'd just dig up).

This is on 30 acres that I'm hoping to seed with orchard grass within a couple weeks. I contracted out the original spraying, but intend to spot spray myself where necessary. What else do I have to do, right? : /

If anyone is dying to see photos of the roots, I'll post those tomorrow.

Thanks, all.


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## danwi (Mar 6, 2015)

A few years ago I was going to spray out a field of orchard grass and alfalfa using glyphosate and 24d when I pulled into the field and started spraying it was taller and more mature then I was thinking, I sprayed the headland and started down the field and I stopped and decided to leave it in hay one more year because it looked so good. Where I sprayed it killed the alfalfa but the orchard grass just took off and grew nice hay.


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## LsHay (Nov 4, 2020)

Wow. Seems like this stuff is more art than science.


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## weedman (Jul 12, 2019)

LsHay, what rate of gly did you use the first time?


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## Markpnw (Dec 27, 2019)

Well the biggest thing is you applied it in July. The best time to apply is do an application in the fall then do 2 more in the spring. 2-4d and dicamba don’t kill grass only broadleaf. That said if I were you, I would spray glyphosate around 2pints an acre then plow it over in 2-4days. Then wait for any kind of regrowth and spray glyphosate with 24d or dicamba because you’ll probably have broadleaf pop up as well. That way you damage the grass and destroy the rootsystem and will not allow for recovery.


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## LsHay (Nov 4, 2020)

weedman said:


> LsHay, what rate of gly did you use the first time?


1 1/2 quarts/acre


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## weedman (Jul 12, 2019)

I would have thought that rate would’ve killed it. If it were stressed from drought, all bets would be off. Otherwise, I would’ve expected it to work. You are using relatively new glyphosate?


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## broadriverhay (Jun 13, 2014)

Does the age of glyphosate determine it’s effectiveness?


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## weedman (Jul 12, 2019)

it can. Certainly not a year old. A lot has to do with how it is stored. If in a hot barn, it can be affected. Same if it goes through freezing and thawing. Generally this isn’t a problem, though. Where I see it fail is when it is several years old, and it definitely can lose effectiveness over time.


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## rjmoses (Apr 4, 2010)

In one picture, it looks like Johnson grass. 

Johnson grass is highly invasive and EXTREMELY difficult to kill. It is one of the plants that grows from rhysomes, seeds, and tillers. Disking or plowing causes it to double/triple because it only takes about an inch of the root to start a new plant.

The mistake most people make went spraying Johnson grass is to go too heavy. Too heavy and it kills the top of the plant but leaves many root segments alive and you end up with more plants. One recommendation, which I follow myself, is to use a half rate which gets more of the roots.

Around here, it is spread mostly by the road districts who mow the roadsides after it has gone to seed but not yet dropped. It's a major problem hereabouts.

Johnson grass also produces cyanide when stressed, making it poisonous to livestock.

If I was to design the perfect plant--it would be Johnson grass.

Ralph


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## LsHay (Nov 4, 2020)

weedman said:


> I would have thought that rate would’ve killed it. If it were stressed from drought, all bets would be off. Otherwise, I would’ve expected it to work. You are using relatively new glyphosate?


I contracted the spraying out to a large, well-established and respected outfit. I'm confident they use fresh product.


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## LsHay (Nov 4, 2020)

rjmoses said:


> In one picture, it looks like Johnson grass.
> 
> Johnson grass is highly invasive and EXTREMELY difficult to kill. It is one of the plants that grows from rhysomes, seeds, and tillers. Disking or plowing causes it to double/triple because it only takes about an inch of the root to start a new plant.
> 
> ...


I've dealt with small patches of Johnson grass in the past. This is NOT Johnson grass. I am certain about that. I can see Johnson grass in my sleep. The rhizomes of this weed are much smaller, and the leaves are more delicate.


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## Markpnw (Dec 27, 2019)

LsHay said:


> I contracted the spraying out to a large, well-established and respected outfit. I'm confident they use fresh product.


A well established and respected outfit doesn’t make me confident in them. They might’ve had uncalibrated equipment or the outfit had to get rid of glyphosate that was old.one of the reasons they could’ve messed up the rate is if quite a bit of rinsate was put into the tank. I still find it odd why they would spray 24d to spray grass just very confusing. I would understand if it was infested with broad leaf.


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