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New Farm Has Johnsongrass -- Personal Experiences?

I just closed on a new farm which does have johnsongrass present. Of course the majority of it is in the part of the pasture that the horses will be on. :sigh: I will be working with the county extension office to eradicate it but am unsure of what to do with the horses in the meantime…

I have read plenty of research articles and such but they all seem to contradict themselves and offer vague information. So, does anyone have any personal experience with this lovely weed? Did you graze it or keep horses off completely?

Thanks in advance!

It is in my pasture but the horses don’t much like it so they don’t eat it. When the grass dies back I feed lots of hay. The stuff is the scourge of the earth and I would like to poison it into oblivion but have not been able to do that. I have been able to kill it in a small pasture by mowing close to the ground with my riding mower weekly . Obviously this will not work in a big pasture. Farmers also kill it in a hay field by spreading herbicide with a wick that distributes the herbicide on the taller “swamp grass” and not on the shorter desirable grasses. I have never heard of it poisoning a horse around here and it grows everywhere.

It’s all over my property. :frowning:

But the good news is, it only seems to grow in disturbed or undesirable areas. It springs up around the fencelines and in the manure pile, but never seems to become established in the pasture. I’ve heard that’s because it doesn’t tolerate competition from other grasses and hoof traffic/grazing all that well.

Why are there so many plants that can kill horses?!?

I see it everywhere around here, but have never heard of a confirmed horse death from it… so maybe the prussic acid problems are as rare as they say?

they entirely ignore it and eat around it. Occasionally we get a square bale with some in it- they won’t eat one stem of it.

I have been trying to kill the stuff for years. Tip: Johnson grass thinks that glyphosate is fertilizer.

we just mowed it into extinction

Very glad to hear that the ill effects to horses may not be as widespread as some articles make it out to be! I haven’t heard of anything in my area regarding horses but I do know of a farmer that lost a cow to nitrate poisoning last summer.

The extension agent recommended using Outrider to spray because it is supposed to only target Johnsongrass. Maybe that will help others fighting this same problem!

I will definitely try the mowing technique in paddocks at least. I wish that were more practical in the big pastures! We are going to have to knock everything down a considerable amount in the next few weeks anyways because the grass is so tall in places that you can’t even see to build fence. Once that is done, it sounds like me and the lawn mower have a date!

Does anyone have a guidelines that they follow pertaining to the “stress periods” of JG?

Thanks for the insight everyone! Makes me feel better for sure!

I have had it off and on, spray pretty heavily different chemicals (pastora and another that also targets crab grass the bane of my existence! For the most part it has died back now. I have also been known to hand pull it. 50/50 glycophosphate/water in a wiper that just targets the JG (is grows taller quicker so can use this to target JG) http://www.spraysmarter.com/smucker-atv-mount-top-crop-weed-wiper-kit.html?gclid=CjwKEAiAqJjDBRCG5KK6hq_juDwSJABRm03hKnHLUrA7Tdz0uwhD-SvLcNHMpFb7_SvARsp1FMXceBoCYEjw_wcB

My vet long ago told me she had never run into a problem with JG and horses. It is pretty prevalent around here.

We have it too. An old gelding of mine used to eat the tops of the Johnson grass but once it got to a certain height, he wouldn’t touch it. The donkeys do the same thing. The old gelding lived to well into his thirties; the donkeys are sassy and robust. The other horses seem to leave it alone entirely.

My advice: mow it when you see it, but don’t worry about it to distraction.

Be very careful as yes horses can eat it but with a drought the toxin will kill your horses. At least here in NC it is impossible to get rid of and myself and several friends have backed out of buying farms that were infested with Johnson grass.

I don;t get why people want to buy trouble when its enough work to take care of the place and horses. For the whole time you live there you will be dealing with this trouble, monitoring the grass, making sure its not toxic stage, moving horses on and off it and many horses love the stuff like sugar to them
Really don’t buy trouble …why?
And it doesn’t kill cows so don’t use that as your guide…


And it doesn’t kill cows so don’t use that as your guide…[/QUOTE]

Johnsongrass can kill cattle. Stressed johnsongrass (from drought or frost) can contain prussic acid/cyanide and/or high levels of nitrates.

If there is a persistent problem and all farms carry Johnsongrass in some areas walkers, how is it that one would get around this problem? You are not adding much to the discussion because the OP has already bought the property and is looking for USEFUL suggestions as to how to manage it or if/when it is a threat to her horses. Useful discussion for me as we are toying with the idea of moving to Kansas and buying a small farm. Thanks for posting OP.

I’ve got in one pasture in some amount, and in a couple of others it’s a trace.

Keep the pasture mowed and it’s less of a problem as the toxin develops along with the top of the plant. Don’t let it grow a top and you’ve gone a long way toward solving the problem.

Eradication means a re-do of the pasture with a generous dose of RoundUp (or some other broad spectrum herbicide). The optimum time around here (East TN) for pasture re-do with cool season grasses is the fall when you can get two growing seasons on field before grazing or cutting it again. Since my warm season grass areas don’t have any I’ve not researched it for that.

Here are some links I found:




This is not a cheap project nor one that will be done in a day or two. Be prepared for the Long Haul. :wink:


If you have Bermuda grass there are a couple herbicides that are effective in getting rid of johnsongrass in pastures - outrider (maverick) and pastora - but not for use on cool-season grasses such as fescue, orchard or on legumes (alfalfa and clover)


Johnson Grass primer; http://extension.missouri.edu/p/G4872

I have an older Merck Manual that states that Johnson Grass is toxic to all species. Recently, I’ve read several scholastic articles that say it isn’t particularly toxic to horses. When I had it, I killed it.