# Johnson Grass - It's Coming.....



## VA Haymaker (Jul 1, 2014)

Over the summer around my neck of the woods, in addition to the usual milkweed, stick-weed, Queen Anne's lace that I see in fields as I drive around the area, this year for the first time, I really noticed small patches of Johnson grass taking hold. On our farm, we don't have it - yet, but killed a patch that was beside to our land next to a highway. I see a LOT of it along the roads.

Not sure where the seeds are coming from, maybe trucks hauling square and round bales through the area are dropping Johnson grass seeds. We have an autumn olive problem around here too and one of the main culprits over the years is wild life eating the seeds and poop them out onto other properties as they move around. Maybe that's where some of the Johnson grass is coming from.

So I want to be prepared for this potential invasion.

I understand the herbicide part of killing Johnson grass, but have some questions about toxicity of Johnson grass and how to understand/deal with it.

The concern is not necessarily stress and/or frost induced prussic acid. I think I might understand this. Sounds like the cure for prussic acid is to wait for a couple weeks after a post drought rain or a frost and it dissipates? If you bale Johnson grass, wait about a month and the prussic acid dissipates too? I can find much info Johnson grass and prussic acid issues, however, straighten me out if any of the above isn't accurate.

The concern is nitrate poisoning. How does it occur, is the toxicity permanent? In other words, we get a frost or drought stress period, will the nitrate levels go back down to a safe level prior to cutting/baling or is there another trigger for nitrate poisoning? I'm to understand that if the nitrates are in Johnson grass when cut, you're stuck with it whereas prussic acid dissipates over time?

I gather horses can tolerate Johnson grass better than cattle due to how they process gas. Sounds like cattle will bloat and suffocate on toxic Johnson grass?

When you find Johnson grass, how do you deal with the toxicity - especially nitrate poisoning side of it?

Some I read say it's great hay, some say it is a noxious weed. I don't want any part of it (I think), but would like to know the fall-out if there is a patch that comes up in my fields over next summer and beyond. I think in our area, ready or not - Johnson grass is coming....

Thanks,

Bill


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## Colby (Mar 5, 2012)

I don't care for Johnson grass, actually I hate it. If it was me I'd kill it and be done with it. Other people will argue with me on here that it's the best thing in the world.


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## Trotwood2955 (Sep 4, 2012)

Do whatever you can to kill it - spraying, clipping seed heads, digging up the roots - whatever it takes to not let it take hold. If you can keep it sprayed for enough years and never let it go to seed you should eventually get rid of it. I don't know why but I'm noticing a lot more patches along our roads too the last few years. Drives me nuts. I try to fight it with a vengeance. But some do/will not and I'm worried it's only going to get worse because of that complacency. I know some down south have fields full of it and make hay on it. Whatever works for them. In our area and my personal opinion it's an invasive weed pure and simple. If left unchecked it can take over a grass hayfield in only a few years. At that point you pretty much need to rotate the field to corn or beans.

As far as nitrate poisoning I never worried about it much cause like I said I fight the stuff and fortunately have very little and probably never baled enough up to worry about. I'm sure it follows the normal nitrate poisoning guidelines though - don't cut it before it is at least several feet tall, usually don't need to worry unless you applied heavy nitrogen and then went into a drought period followed by heavy rain and then mowing right after the rain (N uptake is heavier during this period), etc.

My main opinion though is concentrate more on fighting it than baling it. Or at least keep it in your part of the state!


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## Tim/South (Dec 12, 2011)

I would rather have Johnson Grass than the Vasey grass weed. They look similar. Neither one is desired though Johnson Grass does have a little feed value.

Vasey Grass has invaded our area with a passion the last three years.


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## TJH (Mar 23, 2014)

You either like it or you don't. It's in the Sudan family along with Sudex and millets. If treated as such when about waist high it's excellent hay. If you pour the nitrogen to it and it turns dry it's deadly, the same as frost killed, however Milo and Pearl Millet will do the same. Most county agents can send it to be tested which most won't do because it cost. Cattle won't bloat or suffocate, their stomach turns the prussic acid to oxalic acid and will kill them in 2 to 3 hours, it's pretty quick. The grass is easy to kill by mowing before it goes to seed, if you let it go to seed it can lay dormant 25 years. Mow it again in the fall so its root reserves dwindle and it will eventually go away. Cattle can eradicate it in two years by grazing it to the ground, and they will. When we bought our place 12 years ago it was covered in it, now there's none. It was grazed out. I fought it all my life when we were farming, then I learned to live with it. It's funny now all these "weeds" (Johnson Grass, Crabgrass etc.) I hated and spent $$$$ to kill, now it love them. You will be able to keep it in check, however you will have to be on your toes. It won't much depend on what you do as much as your neighbors as to whether they let it go and don't fight it. Road right of ways are nothing but nurseries.


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## Waldo (Apr 29, 2016)

The amazing thing with jd grass just when you think you have it beaten ,up it comes.We ripped a line for poly pipe to go in hah,not seen jd grass in it for years .But up it came thick as hairs on a cats back.and with it came a heap of other nasties bathers burr ,castra oil and nut grass just shows how long and how much seed is in the ground


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## Vol (Jul 5, 2009)

Pastora works very well on killing JG....but it will kill most other grasses too, but not all. I keep it on hand to spot treat new uprisings. I try to keep my land as free from JG as possible. That means annual attention.

I use a Red Weeder wiper applicator for most situations and just hand wipe. That way I know it's been affected.

Regards, Mike


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## Tx Jim (Jun 30, 2014)

I think JG is good hay when managed correctly. Most animals will eat immature JG before they eat other grasses. Most horse owners don't like JG but I owned a horse that was prone to impact .that required a trip to vet for clean out. Vet advised me to feed her JG hay. Problem was solved. I never witnessed nitrate poisoning in JG but high applications of nitrogen fert could cause the problem in drought conditions. Nitrate poisoning is concentrated in lower portion of stems so cutting stems 4'' high or higher will lower possibility of nitrate poisoning. Local dairyman will give premium for immature JG hay.

I don't like JG that's growing in a Coastal field as JG doesn't dry down for baling at same time as Coastal.

Intensive grazing will kill JG.


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## Troy Farmer (Jul 31, 2011)

Wild hogs love it too (the roots). Another reason to keep it in check.


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## Grateful11 (Apr 5, 2009)

Don't let JG get out of control, I think you'll regret it down the road if do, you nip it in the bud now. Late FIL hated the stuff and before spraying it he would always remove the seed heads and dispose of them and managed to keep it at bay. To this day there's only a couple small sprigs of it along the road of one field they tend. I sprayed it two or three times and thought it was gone as it didn't come back last year surprisingly it came back this year. I've seen many places where people have let it run rampant and man it's awful.


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## endrow (Dec 15, 2011)

Yes 10 years ago Johnson grass was that bad here in central Pennsylvania grew everywhere. The birds did an excellent job of Distributing it. If you took a lot of Johnson grass somewhere for sale in these parts they would tar and feather. Prior to Roundup Ready beans I probably covered about a half a million acres in my life with a wick applicator and an old Honda big red 3-wheeler. If it works for you okay I hate it


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## luke strawwalker (Jul 31, 2014)

leeave96 said:


> Over the summer around my neck of the woods, in addition to the usual milkweed, stick-weed, Queen Anne's lace that I see in fields as I drive around the area, this year for the first time, I really noticed small patches of Johnson grass taking hold. On our farm, we don't have it - yet, but killed a patch that was beside to our land next to a highway. I see a LOT of it along the roads.
> 
> Not sure where the seeds are coming from, maybe trucks hauling square and round bales through the area are dropping Johnson grass seeds. We have an autumn olive problem around here too and one of the main culprits over the years is wild life eating the seeds and poop them out onto other properties as they move around. Maybe that's where some of the Johnson grass is coming from.
> 
> ...


Johnsongrass, like just about anything, can be wonderful or terrible-- it's all in the conditions and how you manage it.

First, the prussic acid issue. Prussic acid (hydrogen cyanide) is formed in the plant as a response to stress. It usually occurs immediately after the green plant is frosted, or after a dry spell or drought where the plant has been stressed enough to roll its leaves and then gets some rain and experiences a growth flush from the sudden water availability. Prussic acid is really only a problem if the johnsongrass is grazed off immediately, green-chopped and fed, or ensiled in silage or baled green and wrapped in balage or haylage. If the johnsongrass is cut and allowed to cure as dry hay, the hydrogen cyanide outgasses from the plant tissues with the moisture as the plant dries down during the curing process... by the time the hay has dried to safe moisture levels for baling and storing as dry hay, it's gone and not a problem. Livestock allowed to graze green johnsongrass containing prussic acid will die very quickly, as hydrogen cyanide is one of the most toxic substances known to man. Giving frosted or recently growth-flushed johsongrass a week (or 10 days or so if you're really worried) to recover from the stress is usually sufficient to allow for dissipation of the hydrogen cyanide in standing forage that you want to graze or chop.

Nitrate poisoning can occur in virtually ANY grass-type crop, though of course some species are more prone to it (like johnsongrass and other related sorghum-type crops, corn, etc) than others. The nitrate problem is usually confined to heavily fertilized johnsongrass and sorghums/corn that have experienced prolonged drought conditions and then been cut for hay or chopped for silage or wrapped for haylage/balage. How it happens is, the plant is growing in highly fertilized soil with high nitrogen fertilizer availability, but water is the limiting factor preventing growth. The plant has a physiological response where it absorbs the nitrogen, but doesn't have the water available to use it in the plant, so it "stockpiles" the nitrate in the plant tissues, where it will be immediately available for use in the plant when and if more water becomes available (after a decent rain). If that rain never comes, the nitrate simply remains in the plant unused. If the plant is cut for hay, chopped for silage, or cut and wrapped as balage/haylage, the nitrates go into the finished forage. Nitrates DO NOT dissipate with dry-down into normal dry hay, unlike prussic acid. Livestock fed high-nitrate containing forages, even months later, can experience difficulty breathing and in sufficient quantities, die from asphyxiation. Livestock so affected will have "chocolate milk blood" as the blood, instead of being bright red, will be dark brown and thick like chocolate milk, due to the nitrates tying up the hemoglobin so it cannot carry oxygen in the blood to the body, causing death. The solution to high-nitrate forages is TESTING to determine actual nitrate levels, then DILUTING the high-nitrate feed by grinding/chopping and mixing it with non-high-nitrate feeds to dilute the nitrate down to safe levels, or avoiding high-nitrate containing forages. If you have just a spotty infestation of affected johnsongrass in otherwise safe, non-high-nitrate hay, it shouldn't be a problem. Note the risk of nitrate poisoning only is really a problem in HIGHLY NITROGEN FERTILIZED FIELDS that have experienced PROLONGED DROUGHT CONDITIONS. In a drought in Texas a few years ago, there were hundreds of thousands of acres of corn and grain sorghum that was highly fertilized for grain production that due to the drought never produced a grain crop sufficient to harvest, so many farmers wanted to simply cut and bale the crops as dry hay or balage and sell it to livestock farmers who were also in dire straits due to low hay production and bare pastures and short grass in grazing pastures... The extension service put out a lot of alerts reminding livestock producers to TEST the forages produced from such fields for high nitrate and be sure to avoid it or dilute it down with proven non-high nitrate forages mixed with it to prevent animal loss. If you DON'T heavily fertilize the crop, or you get RAIN and allow the forage to have a growth spurt and use up the nitrogen in the plant tissues BEFORE harvesting it, the nitrates will be gone or greatly reduced. Plant tissue or hay sample analysis can tell you nitrate levels through TESTING...

Cattle CAN bloat on many different rich forages, but that's not usually the problem with johnsongrass... bloat in cattle is a different phenomenon, usually caused by cattle eating excessive amounts of susceptible legumes or grasses (like lush ryegrass) that can form foam bubbles in the rumen, which the cow cannot 'burp" out, causing the rumen to inflate and take up so much room in the abdomen of the animal that they cannot draw a breath, causing suffocation. Johnsongrass is called "ice cream grass" in that cattle, like kids in a candy store, will preferentially eat it over virtually anything else (in fact, the best way to eliminate johnsongrass is just to graze a pasture or paddock where johnsongrass is growing-- they will LITERALLY eat it to death-- they'll eat it down to the ground and keep eating it until they deplete the roots (rhizomes) and the plant dies-- they'll completely eliminate it... The problems with prussic acid containing johnsongrass is they hydrogen cyanide, which causes instant death in sufficient quantity (even a mouthful or two is enough), and in high nitrates, ingested in sufficient levels, will cause animal breathing difficulties and eventual asphyxiation from the blood being unable to carry oxygen to the body tissues of the animal (chocolate milk blood).

SO, that's the facts... and how you manage it. The conditions you really have to look out for is drought-stressed johnsongrass... if it's been HEAVILY NITROGEN FERTILIZED and hasn't grown much due to prolonged drought, it could be high-nitrate. A light, spotty infestation in otherwise 'clean' non-high-nitrate hay shouldn't be a problem, but IF IN DOUBT, TEST. If it rains and the johnsongrass (and other forage) recovers and grows out before it's harvested, the nitrate should have dissipated to safe levels or be gone. If it's drought stressed and receives a rain sufficient for a lush greenup or is frosted and is to be harvested for forage, cutting and curing it for dry hay will dissipate any prussic acid during the drying process. If it is to be grazed or chopped or baled green, wait a week or two for the hydrogen cyanide to dissipate from the plant through normal respiration before allowing it to be grazed or chopping and feeding or ensiling or baling and wrapping/bagging.

If you want to eliminate it, the easiest way is to use a wick applicator with a 33% Roundup solution. We used to keep johnsongrass at bay in cotton fields with a wick applicator (both the rope type and the canvas cloth type) mounted on the front of the cultivator tractor. Spot spraying it also an option. The most cost-effective way is to put some cows into an affected pasture and allowing them to graze it to death... we don't have a sprig of it on the farm anymore after we quit row cropping (after years of grain sorghum production, which due to being closely related to johnsongrass, means control of johnsongrass becomes very difficult and it flourishes and spreads) once we fenced the farm and started grazing cattle on all those old fields. I'd love to have more of the stuff actually... it's TERRIFIC forage if properly managed...

Later! OL J R


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## azmike (Jan 4, 2015)

University of Michigan writes:

When sorghum-family forages are cut for hay, prussic acid dissipates as the hay dries and hays are safe to feed once bales have reached the stable storage phase. This is also why frosted sorghum-sudangrass is safe to graze after it has field-dried to "standing hay." "Green" sorghum hays that are still in the heating phase should not be fed. Prussic acid is destroyed by ensiling and is gone by the time fermentation is complete. A good rule of thumb is to wait three weeks after harvest before feeding hay or silage made from sorghum-family forages.


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## r82230 (Mar 1, 2016)

azmike said:


> University of Michigan writes:


Amike,

I am in Michigan, are you sure this came from U of M? The reason I ask is Michigan State University is known as our ag college, U of M turns out a lot of liberal lawyers and doesn't have a ag division the last I knew (but I could be wrong).

I am not doubting your info in anyway, just questioning the source. If it did come from U of M, then I guess I will start reading more of their stuff (screening out the liberal stuff if possible, I don't want my cows to be limited on passing gas, like California liberal cows apparently are).

Larry


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## azmike (Jan 4, 2015)

EXTENSION

Michigan State University Extension helps people improve their lives by bringing the vast knowledge resources of MSU directly to individuals, communities and businesses.

Frosted sorghum-sudangrass pasture poses prussic acid poisoning risk

Sorghum-family plants can contain prussic acid that is potentially lethal to livestock.

Posted on *October 1, 2012* by *Kim Cassida*, Michigan State University Extension, Department of Plant, Soil and Microbial Sciences








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## rjmoses (Apr 4, 2010)

Johnson grass has spread like wildfire around here and just across the river in Missouri, especially along the roadsides!

The reason: Simple! The road districts shred the roadsides shortly after the JG has gone to seed, thereby spreading the seeds better than any deer or bird could ever think of doing! They do this to save money by mowing the roadsides less often.

I use a weed wiper loaded with a mild RU mix. Too strong a RU mix kills the top but not the roots and you end up with more plants because all it takes is a 1" long section of a root to start a new plant. That's why plowing/discing JG is a B-A-D idea!

Ralph


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