johnson grass
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Banjo":cyl4ieil said:
Tennesseans too!
greybeard
Well-known member
I've read this thread (and others via CT search) and still don't understand JG and it's toxicity periods. I have a small pasture, full of good green bahia/common bermuda/coastal bermuda mix, but with some green JG about 3 ft tall stalks with seedheads on it, and I'm now scared to let some 500 lb heifers in on it. July was very dry, Aug a fair amt of rain and Sept saw a LOT of rain including 5" last week. It was last grazed in mid August, but not heavily.
Toxic during drought stress--got it! (doesn't apply now)
Toxic after first frost-got it! (doesn't apply now)
If kept grazed short from the start, not usually a problem--got it! (doesn't apply now)
But, "sometimes" toxic after a rain and requires a 10 day waiting period before grazing?
Is it usually toxic at the mature stage mine is in?
(I can cut it down, rake it and burn it manually if that's the only recourse) I do not have a test kit and have no idea where I would find one around here.
suggestions?
Toxic during drought stress--got it! (doesn't apply now)
Toxic after first frost-got it! (doesn't apply now)
If kept grazed short from the start, not usually a problem--got it! (doesn't apply now)
But, "sometimes" toxic after a rain and requires a 10 day waiting period before grazing?
Is it usually toxic at the mature stage mine is in?
(I can cut it down, rake it and burn it manually if that's the only recourse) I do not have a test kit and have no idea where I would find one around here.
suggestions?
From what I have figured out you should not have a problem with nitrates as much rain as you have had. Also it seems to me it has been long enough after your last good rain that prussic acid should be gone.
If you are nervous like me you can get a cyantesmo strip test kit. I bought mine from Amazon it took 3 days to get and cost about $55.00 dollars but should last a long long time.
If you are nervous like me you can get a cyantesmo strip test kit. I bought mine from Amazon it took 3 days to get and cost about $55.00 dollars but should last a long long time.
Cowgirl Brit
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Don't graze sorghum or sudan pastures between the first frost and a definite killing frost because of the
danger of prussic acid poisoning. Johnsongrass in stalk fields can also be a problem after a light frost.
Grazing can resume after the sorghum-type grasses have undergone a killing frost and dried up.
danger of prussic acid poisoning. Johnsongrass in stalk fields can also be a problem after a light frost.
Grazing can resume after the sorghum-type grasses have undergone a killing frost and dried up.
Lucky_P
Well-known member
I generally don't worry too much about nitrates in JG or any other plant, if they're growing on unfertilized pastures, like mine. If, however, you're still funding the fertilizer plants and spending a lot of $$ on high-N fertilizers, it could be a problem.
Prussic acid, however, can be an issue, regardless of soil fertility. Generally, I don't worry much about that either, as fast as we rotate around the farm - unless there was a lot in a paddock that had been frosted - but usually, we've already pulled cows off pasture to allow stockpiling before we get a killing frost/freeze.
Prussic acid, however, can be an issue, regardless of soil fertility. Generally, I don't worry much about that either, as fast as we rotate around the farm - unless there was a lot in a paddock that had been frosted - but usually, we've already pulled cows off pasture to allow stockpiling before we get a killing frost/freeze.
So what is the best way to deal with frosted Jgrass. Does it take a killing frost to activate the prussic acid? What about scattered light frosts? I always get concerned this time of year, with frosts just around the corner.
Lucky_P
Well-known member
Frosted, I'd want to wait at least a week before turning the cows on it. Prussic acid will have pretty well dissipated in that time frame.
Found this blurb somewhere:
After a non-killing frost, do not allow animals to graze the frosted plants that are shorter than 30 inches in height for 10 to 14 days. Plants above that height can be grazed after a 4-5 day period.
Found this blurb somewhere:
After a non-killing frost, do not allow animals to graze the frosted plants that are shorter than 30 inches in height for 10 to 14 days. Plants above that height can be grazed after a 4-5 day period.
I know the above post is a few months old but I just saw it and need to address it before it causes someone to lose catttle to prussic acid poisoning. I have lots of JG and have to manage it properly. I work both with OSU extension and Noble foundation in doing so. When JG is short and growing is when it is absolutely the most dangerous. You can get test strips to test a field before turnout. The only time I have them test positive is when the grass is young, tender and growing. It is typically NOT dangerous during a drought, but directly after an 1/8 inch rain following a drought, and for 10 days after a frost. The dissipation rate varies and can take anywhere from 4 days to 2 weeks. I currently have plenty of grass but am unable to move cattle because my fields tested positive on Friday after a rain.OklaBrangusBreeder":37yuut6t said:
I've heard it takes a killing frost for the prussic acid to form and light frosts isn't problem. I don't know. All of mine right now is tall and headed out because there have been no cattle there for 2 to 3 months. I have a neighbor who turns his cattle in on a hay field this time of year that is covered up in Jgrass but it is mature and he has no problems.
cross_7
Well-known member
Do not graze wilted plants or plants with young regrowth.
Do not use frost damaged sorghum as pasture or green chop during the first seven days after the first killing frost. Delay pasturing for at least seven days or until the frosted material is completely dried out and brown colored
Do not use frost damaged sorghum as pasture or green chop during the first seven days after the first killing frost. Delay pasturing for at least seven days or until the frosted material is completely dried out and brown colored
It's better to have scientific proof than listen to a neighbor. This is the second test on this field in 9 days. It's been hot both times and hot enough that one bite will kill em. My day time temps are 75, with nights in the 50s.Banjo":lrnzecea said:
This test was run today.
Is that JG that has been frosted on? Thanks for the advice.Isomade":2cer3e60 said:It's better to have scientific proof than listen to a neighbor. This is the second test on this field in 9 days. It's been hot both times and hot enough that one bite will kill em. My day time temps are 75, with nights in the 50s.Banjo":2cer3e60 said:
This test was run today.
No frost, it does NOT need a frost to be toxic.Banjo":1pf182c4 said:Is that JG that has been frosted on? Thanks for the advice.Isomade":1pf182c4 said:It's better to have scientific proof than listen to a neighbor. This is the second test on this field in 9 days. It's been hot both times and hot enough that one bite will kill em. My day time temps are 75, with nights in the 50s.Banjo":1pf182c4 said:
This test was run today.
Fresh rain can make JG toxic. The most dangerous time is when it has been eaten down, then gets a rain. Regrowth sprouts are the most dangerous. JG is seldom dangerous during drought conditions, it is just after the drought and after a frost on young plants that it is usually fatal. Prussic acid is cyanide, it works like a defense mechanism for the plant.
greybeard
Well-known member
Yes, that's the way I understand it too. Frost is just one aspect of the picture.
Pretty good article here:
http://forages.oregonstate.edu/fi/topic ... dpoisening
And tho it wasn't JG, (that I know of) if ya remember the Bastrop Texas case where a whole herd was killed by prussic acid in Tifton 85, it happened in June in Central Texas.
Pretty good article here:
http://forages.oregonstate.edu/fi/topic ... dpoisening
And tho it wasn't JG, (that I know of) if ya remember the Bastrop Texas case where a whole herd was killed by prussic acid in Tifton 85, it happened in June in Central Texas.
I am wondering if clover works the same way as far as being toxic or making cattle bloat after a rain. I lost a 500lb heifer calf last year......it was just after an extended dry spell and then 2 inches of rain....a couple of days later found her dead.....there was no JG is this field.
At the present time all my JG is very mature however, we are expecting a hard freeze in a couple of days, so I am going to feed hay for a couple of weeks and keep them off it till the threat is past.
At the present time all my JG is very mature however, we are expecting a hard freeze in a couple of days, so I am going to feed hay for a couple of weeks and keep them off it till the threat is past.
I bought the same test strips Isomade has and I am feeding hay now because my pasture keeps testing positive for Prussic acid.
It is the new growth showing prussic acid, it was not frosted on at least until night before last.
I am just going to wait for a hard freeze and hold them out for a couple of weeks. We are supposed to get down to 29 in a couple of days, I don't know if that will do it or not.
It takes my samples a few hours to turn bright blue. I do the same thing Isomade does ( I think) I chop up Johnsongrass and put it in a zip lock bag in the sun. I have tried other kinds of grass and get no results.. just in case someone doubts..
If you don't think cherry leaves are toxic, just put some wilted ones in a bag with a cyantesmo strip. It almost instantly turns bright blue.
It is the new growth showing prussic acid, it was not frosted on at least until night before last.
I am just going to wait for a hard freeze and hold them out for a couple of weeks. We are supposed to get down to 29 in a couple of days, I don't know if that will do it or not.
It takes my samples a few hours to turn bright blue. I do the same thing Isomade does ( I think) I chop up Johnsongrass and put it in a zip lock bag in the sun. I have tried other kinds of grass and get no results.. just in case someone doubts..
If you don't think cherry leaves are toxic, just put some wilted ones in a bag with a cyantesmo strip. It almost instantly turns bright blue.
