Black Walnut toxicity

[Chuck White]

Sawed a few small logs for a customer the other day, Locust and Maple.

Not a big job though, about 300 bf.

Anyway, he noticed that there were nuts on one of the Walnut trees in the middle of the yard.

I asked him if he wanted a few to plant and he said sure, so we gathered about a dozen for him to take home.

He said that if you have horses, you can't have them pastured where there are walnut trees, because the nuts and maybe the leaves are poisonous to horses.

This guy has been known to be quite a BS'r, so, does anyone here know for sure whether they are poisonous or not?

[Jeff]

They certainly are.  A quick search for juglone on the forum should lead to you to several conversations about it.

[beenthere]

I tried to pass that along to a neighbor who had some prize horses, and their shade trees in the pasture were almost all black walnut. Said they had been there for many years and he wasn't concerned.
Our horses and ponies on our farm were among big walnut trees. So guess it can happen but it isn't a sure thing if you want to get rid of horses.

Bedding them in black walnut sawdust isn't a good idea.

[Al_Smith]

I don't know if they are or not .My dad had Shetland show ponies,the high stepper Arabian cross type .If any thing it might have made them a little more ornery as if they needed any help in that department . At any rate the ponies didn't fool with the walnuts ,just layed under the trees for shade .Scratched their behinds onthe trees in typical horse style .

They claim black cherry is bad for livestock too but I've seen a many growing in the pasture field fence rows .

I dunno maybe Ohio livestock is immune to the stuff ?

[Dodgy Loner]

I've never heard of livestock being harmed by walnut trees - juglone levels in the leaves are very low, compared to the levels in the roots and husks. Hulls are not attractive as a food source for anything other than insects and microbes. As beenthere noted, it is best to avoiding the use of walnut shavings as a source of bedding material.

I think your friend may have been confusing black walnut with black cherry, the wilted leaves of which contain dangerous levels of cyanide.

[Jeff]

The question was, whether walnut is poisonous to horses. The simple answer to that is yes it is.

[beenthere]

Here is a Horse Nutrition bulletin from Ohio. Implies it would be laminitis from shavings in the bedding.
http://ohioline.osu.edu/b762/b762_25.html

Here is one from the horse people side of the coin.
http://www.understanding-horse-nutrition.com/black-walnut-tree.html


Certainly something to be aware of if pasturing horses.

[Chuck White]

Thanks for all the info.

We don't have horses, so there's no problem there.

I was just curious is all.

Good info to pass along to customers.

Thanks again.

[SPIKER]

my niece has BW in her pasture and the horses have eaten much of the leaves & bark off of them over the years.   none have died from it for sure.   though like AL S posted Black Cherries are more of an issue around here.   my neighbor wanted to cut down our line cherry trees so she could pasture her horse on here 1/4 acre lot    finally after I pointed out the line and the barb wire grown into these trees as the existing/known line and that she would need my permission to cut them she gave up the idea of parking her horse over septic system (which is where she was going to put the horse!?!?   yes she is a natural blonde too
mark

[Dodgy Loner]

The question was, whether walnut is poisonous to horses. The simple answer to that is yes it is.

You answered this question (correctly, I might add):

does anyone here know for sure whether they are poisonous or not?

But I was offering a response to this statement:

He said that if you have horses, you can't have them pastured where there are walnut trees, because the nuts and maybe the leaves are poisonous to horses.

I offered the links for more information, since their is no simple "yes or no" answer to the question of whether or not horses can be pastured with walnut trees. I have lumber that was sawn from three walnut trees that were killed because the owner's horses continued to eat the bark off of the trees and sought shade under them for many years. The horses were never harmed by the trees, but the trees were certainly harmed by the horses, and they eventually succumbed to a drought. Based on this anecdotal evidence, one might presume that you can, in fact, safely graze horses in a pasture that contains walnut trees, but a more cautious horse owner (which includes many horse owners) would never consider allowing their horses to graze around a tree that posed the slightest health risk.

[Jeff]

The biggest threat from pasture trees woudn't come from ingestion, it would come from hoof contact with the walnut husks. That's all it takes.  My knowledge of the subject comes second hand though via the parade of horse owners I have met over the years looking for sawdust for bedding. The next most discerning group when it comes to sawdust for bedding after horse owners are Dairy Farmers.  All kinds of udder particulars there. (pun intended)

[T Welsh]

As Jeff said, hoof contact! we live in horse country and we sell a lot of saw dust and processor chips (some of these horses live better than I do) and the first thing they say is there any walnut or cherry mixed in! I have learned over the years to clean up before I cut either one. Tim

[woodsy]

It too has been my experience that horse owners are very particular with sawdust.  The mere mention of walnut sends them fleeing.  I have even been lectured by horse owners about the sawdust being to dusty!

[shelbycharger400]

i have read that they use the byproducts of a steamer kiln from the black walnut as a plant herbicide , and is considered haz. waste.
so naturally its in their somewhere

[Magicman]

Put a batch of green walnuts in a burlap bag and run over it several times with the tractor.  Throw it out into the pond, catfish for supper.  Better be hungry, cause you will kill them all.

[Brad_bb]

I was just reading up on processing of Black walnuts and toxicity to horses was stressed.  It was also said that there is no toxicity to humans.  I also read that once the hulls have been properly composted, they are no longer toxic to anything.  It must break down naturally with composting.

[mrcaptainbob]

Was at the fair grounds today and looking at one of those large antique corn shellers. A guy walked up and said it's also good for walnuts. Huh? He said, "YEP. We used that when I was kid. Drop them in the hole right there. The rind falls from the bottom and the nut pops out here.... No time at all and we'd have them all done."

[beenthere]

The corn sheller is also what we would use when I was a kid. It was the type that had a hand crank and would shell one ear at a time.  Worked good, but was a bear to keep cranking bushel after bushel of walnuts. Did manage to get a small electric motor and belt hooked to it.

[sandhills]

I'm not doubting anyone on the subject of the toxicity to horses, but is it from contact with the hoof or is it from dust inhaled from using it as bedding?  I honestly have no idea, I'm just asking because I just planted some and growing up around horses it seems to me that respiratory problems seem more likely  .

[Ianab]

Here is an actual Canadian Govt Ag Dept page on Walnut and horses.
http://www.omafra.gov.on.ca/english/livestock/horses/facts/walnut.htm

It seem that the Juglone certainly can cause a serious issue, just from standing around on shavings.

They also suggest the fungal spores from mouldy fallen walnuts can be toxic. This is a different form of poisoning, and more likely to cause respiratory issues, if the horses were grazing around fallen walnut husks. That might account for what you have noticed? The walnuts ARE causing a problem, it's just a different one.

Ian