# How much Prussic Acid does it take to kill an animal?



## Texasmark

Was out on my soon to be hay patch yesterday spraying fire ants. Noticed some Johnson grass popping up, not much but it's there none-the-less. Planting Pearl Millet and plan to graze it after haying.

Just wondering how much is too much? I know that it is reduced as the plant grows in height, but grazing can put you back to ground zero. May be a drought here again (stress), and later on cattle may still be on there when the first frost arrives.

Also, when you take your thumb and index finger and wipe a blade is the white powder you sometimes find Prussic Acid?

Thanks,
Mark


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## Waterway64

I don't believe millet should be a problem. Sudan and sorghum when stressed are culprits. I know nothing of johnson grass.


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## TNKid

I have turned cattle in on a pasture with a few spots of johnson grass (20 - 25 square feet each) with no problems. T get rid of it I cut it carefully with a weed eater. Then I pick up all of it, put it in a garbage bag and send it to the dump. It has stayed out pretty good lately. If it is isolated to a few small areas, you can weed eat it and let it dry for a few days before letting cattle in. I believe once it cures that the cyanide levels are low enough to not cause any problems.


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## Vol

Texasmark said:


> Was out on my soon to be hay patch yesterday spraying fire ants. Noticed some Johnson grass popping up, not much but it's there none-the-less. Planting Pearl Millet and plan to graze it after haying.
> 
> Just wondering how much is too much? I know that it is reduced as the plant grows in height, but grazing can put you back to ground zero. May be a drought here again (stress), and later on cattle may still be on there when the first frost arrives.
> 
> Also, when you take your thumb and index finger and wipe a blade is the white powder you sometimes find Prussic Acid?
> 
> Thanks,
> Mark


Here's a good read on Jgrass, with recommendations at the end of the summary.

Regards, Mike

Johnsongrass, Fall Grazing, and Prussic Acid | Farms.com


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## Vol

Texasmark said:


> Noticed some Johnson grass popping up, not much but it's there none-the-less.
> 
> Thanks,
> Mark


Mark, if you only have small amounts of Jgrass, now is the time to treat it to eradicate it as it spreads like wild fire. That may mean sacrificing spots in your fields or pastures for a year or so to treat the infected areas. It may be barren for a year, but for myself is much easier to deal with barren spots than the Jgrass.

Regards, Mike


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## rjmoses

Along road banks of I-270 in st. Louis County, JGrass has completely taken over. It has now spread across the river into our county. The state road guys mow it after it has started going to seed and spread it like mad. I have a continual battle every summer with my fields along the road. I start scouting around August 1st and check at least once a week. I clip the seed heads before they mature and then wack the plant with a Roundup weed wiper. I clip the seed heads because they can mature even after the plant is dead from Roundup.

Don't use too strong a Roundup solution because it will kill the top part of the plant, but not the rhizomes and then you end up with a bigger stand next year!

It's triple action reproduction process, seed, rhizomes and tillering, make it a perfectly engineered plant for taking over an area.

Here's some links to controlling it::

http://cropsoil.psu.edu/extension/facts/agfact4.pdf

http://ag.udel.edu/extension/IPM/ResourceGuide/WF5-Johnsongrass Control in Cropland.pdf

I wish my orchard grass, etc., had the reproductive traits of J-Grass!

Ralph


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## NDVA HAYMAN

Welcome to the wonderful world of Johnson grass. We have been fighting it for 30 or more years. That's why we use weed wipers to kill it. Cattle do love to graze on it. I always wondered why it had not spread out to you guys area. Guess it has. The only sure fire way that I have found to get rid of it is to crop it with roundup ready seeds. I have never heard of prussic acid but will google and find ouy. Good luck. Mike


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## JD3430

Hey guys is johnson grass ok for livestock to eat if it gets baled up in hay? Assuming it will lay on the ground, be allowed to dry and then raked & baled up. By then I was assuming that it would be dried up and the deadly gasses allowed to escape This stuff scares the crap outta me.


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## NDVA HAYMAN

Although we try to and have been successful at getting rid of it, people have baled it for years around here along with whatever hay has been in the field. Cattle do love to eat it in the bale and also graze it. Mike


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## Texasmark

TNKid said:


> I have turned cattle in on a pasture with a few spots of johnson grass (20 - 25 square feet each) with no problems. T get rid of it I cut it carefully with a weed eater. Then I pick up all of it, put it in a garbage bag and send it to the dump. It has stayed out pretty good lately. If it is isolated to a few small areas, you can weed eat it and let it dry for a few days before letting cattle in. I believe once it cures that the cyanide levels are low enough to not cause any problems.


JG has been used here for hay for years before and during the introduction of sorghum/sudans. Curing is said to, and apparently does, allow any poisons to evaproate in the curing process.

I know that Roundup will kill the rhysomes (spelling), the meandering roots that start all the trouble. I might just spray the small patches and be done with it.

Thanks,

Mark


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## bluefarmer

if it was'nt for jgrass i would have had a lot less hay.I personally like it some people think i'm nuts and maybe i am, mississippi state university has alot of info on jgrass


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## Vol

Johnson Grass typically does not start rearing its ugly head here in TN until sometime in May....about the time of first cutting cool season grass. My question is for cattlemen. Do you think that grazing beef on Johnson Grass can weaken or eliminate the rhizomes over time. Can you graze out a vigorous stand of Johnson grass over a period of years if you graze it early on all season?

Regards, Mike


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## bluefarmer

grazing Jgrass will kill it out if you can graze it that is the best economical way to kill it out


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## Mike120

I try to get it with roundup in my weedwiper. I've also used Maverick which works well but it's expensive.


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## cwright

If it isn't damaged by stress (drought/frost) it should be OK. All the reports say "potential". This article also lists other forage species with prussic acid potential.
I have a lot of Johnson Grass that has been put up in hay and fed to cattle with no ill effects.
prussic acid poisoning


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## Guest

Certainly. I join told all above. Let's discuss this question. Here or in PM.


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## darwood

To the op. The white stuff you rub off of the plants onto your finger is not the prussic acid. High Prussic acid concentrations are found in the leaves. Short leafy plants have a higher prussic acid potential than tall, course ones. For this reason, prussic acid poisoning is greater in immature plants or vegatative regrowth.

There is no risk of prussic acid poisoning with pearl millet.

You can reduce the prussic acid content in forages by cutting, wilting and baling. Extensive grazing for several years usually eliminates johnsongrass from pastures.

As far as how much it takes to kill a cow, well, that is variable. There are some things to ask. Have the cows been exposed to it before in a pasture situation? How mature is the grass? Is it more than 18 inches tall? Are the cows unusually hungry when turned into a pasture containing young, immature grass? How concentrated is the johnsongrass in the pasture? Some cows can tolerate grazing johnsongrass, others may not be able to. It doesn't take a lot of young, heavily prussic acid loaded grass to kill a cow.

Rule of thumb for here is, if the grass is under 18 inches tall, don't graze until it gets that tall. If the gass has been stressed by drought or frost, don't graze it until it comes out of the stress period, or dries out from the frost. If the grass has been recently fertilized with a N source, don't graze it until it reaches the maturity as previously.


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## knothead

OUTRIDER it kills johnson grass. Dead
Pastora did not work well for us
Roundup only burns it back


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## tommystunes

I live in se oklahoma and have utilized johnsongrass for years.
Prussic acid is not an issue if baling it for hay.
However, nitrates are an issue. Here the county extension will test for nitrates and give you an idea whether it is safe. Nitrates do not dissipate in the curing process and will remain in the hay.

Grazing is another story,as you will deal with both nitrate and prussic acid poisoning. To the OP: pearl millet will also accumulate nitrates,probably worse than Johnsongrass


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## Texasmark

Here we go again. Grin

I cut the hay patch. Had the regrowth. JG was 10 to 24". Had the string of 100+ days with no rain. Got some rain and cooler weather. Every day I would check the JG and other grasses. About a week after the rains came, I inspected the JG one day and lo and behold the leaves and stems of some of the JG plants were covered with a fine white powder that you could scoop off with your thumb and index finger.

I have had a hunch for a very long time that this is the PA so I cut off some of the leaves and stems, put them and $35 in the mail to TAMU for them to tell me if it is or isn't. You just couldn't get a more perfect scenario, checklist filled out if you will, on the right things to cause the poison.

Soooooo we'll see and I'll get back with their chemical analysis.

Mark


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## Texasmark

Texasmark said:


> Here we go again. Grin
> 
> I cut the hay patch. Had the regrowth. JG was 10 to 24". Had the string of 100+ days with no rain. Got some rain and cooler weather. Every day I would check the JG and other grasses. About a week after the rains came, I inspected the JG one day and lo and behold the leaves and stems of some of the JG plants were covered with a fine white powder that you could scoop off with your thumb and index finger.
> 
> I have had a hunch for a very long time that this is the PA so I cut off some of the leaves and stems, put them and $35 in the mail to TAMU for them to tell me if it is or isn't. You just couldn't get a more perfect scenario, checklist filled out if you will, on the right things to cause the poison.
> 
> Soooooo we'll see and I'll get back with their chemical analysis.
> 
> Mark


I sent in some leaves, stems, and a sample seed head that had something wrong with it.....looked like a cancer.

Analysis came back and told me what was wrong with the seed head, which isn't what I was interested in, and told me that the lab at TAMU did not have the capacity to test for PA. So much for that.

Mark


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## R Ball

Here in Kentucky where I live it gets baled up with everything else and fed. Once the frost hits it and kills it you have to be careful with it foe a couple weeks. Had a old timer tell me that you never see it in a pasture because they like to eat it when it's young.
My cattle get hay with it in it all winter. Our horses get a little sometime also.
Had no problems with it at all.
I might also add that JG is everywhere here. Along side roads, pastures, and etc.. Not sure 
It would be possible to get rid of it all.


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