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  Discussion on Black Locust Trees in my pasture
Author Message
Member:
maribeth

Posted on Monday, Nov 3, 2008 - 11:16 am:

HELP! I have black locust trees in my pasture. We have fenced in and built a barn this summer to make ready for the move of our horses from a boarding facility to our home. We have tree rows of black locust trees and although the horses can't get to the bark, there are small open pods from the trees that have fallen into the pasture as the leaves have been coming down. We also have red maple tree leaves that have blown into the pasture. I'm concerned my horses willpick up either the pods or leaves from these trees and become sick. I just found out that Black Locust and Red maple can be toxic. I have to have my horses moved by 11/8. How concerned should I be about this?
Member:
vickiann

Posted on Monday, Nov 3, 2008 - 12:23 pm:

Maribeth, I seem to recall others posting about horses becoming quite sick from eating Black Locust. As to the red maple leaves -- when wilted, they are very dangerous. I believe I recall a Veterinarian telling me that they cause the blood corpuscles to explode. If they were my horses I would be very concerned about either situation but even more about the red maple leaves. Maybe your horses won't eat either but maybe they or one will. I wouldn't dare to wait and take the chance.
Member:
scooter

Posted on Monday, Nov 3, 2008 - 8:22 pm:

Yah I have had reactions to the black locust pods twice!!! We don't even have them in our pasture, but the neighbors do and it never fails when they are ripe to fall we get a 50mph west wind and they end up in the horses pasture.(right now there are hundreds in there) I have the part of the pasture that they land in fenced off with a temporary elec fence until I can get them raked up and thrown back into the neighbors pasture, that solves the problem, but it is a cumbersome job....better than sick horses tho.

The Red maples would worry me more. Can you put up a temporary fence where they fall until you can get them cleaned up?
Moderator:
DrO

Posted on Wednesday, Nov 5, 2008 - 9:54 am:

Hello Maribeth,
The leaves, seeds, and bark of black locust (Robinia pseudoacacia) are all considered toxic. Double check to be sure these are not honey locust trees. It is ingestion of the bark that seems to be most reported and I suspect these horses were in a situation where forages were limited leading to chewing of the bark.

Robin (or robinin) and phasin, which are toxic proteins called toxalbumins, are present in black locust. A glycoprotein that agglutinates red blood cells has been extracted from the plant. It is not clear if this is robin or another substance. Experimental feeding to horses has shown the following toxicities:
  • aqueous extract of bark about 0.1% of body weight caused symptoms
  • powdered bark about 0.04% of body weight caused symptoms

Horses that ingested black locust leaves, sprouts, and bark were poisoned and died. Symptoms are similar to those of cattle and include anorexia, weakness, posterior paralysis, nausea, coldness of the extremities, and pupil dilation. Symptoms of colic also occur. In severe cases, death occurs. Postmortem findings showed mucous inflammation of the gastrointestinal tract and occasional severe gastroenteritis. In some cases a yellowish pigmentation of the membranes occurred (Hansen 1924, Kingsbury 1964).

This is a common tree in pastures and poisoning rarely reported so the degree of risk is small but not zero. If you are concerned about this consider mowing the areas that the seeds DrOp with a grass catcher to pick them up. For more on this check out the Canadian Toxic Plant site. You will find a link at Diseases of Horses » Poisons , Venoms & Poisonous Plants » Poisons, Poisonous Plants, and Venomous Animals.
DrO
Member:
maribeth

Posted on Wednesday, Nov 5, 2008 - 1:18 pm:

Thank you for the information. We have electric fence around the trees so the horses won't be able to get to the tree itself. We are mowing the pasture down so I can clean up the leaves and pods daily which should reduce the risk of them ingesting one or the other. You are right, Black locust are everywhere it seems, they spread quickly and are hard to control once started. Thanks Dr. Oglesby
Member:
vickiann

Posted on Wednesday, Nov 5, 2008 - 7:13 pm:

Maribeth, Dr. O has a very good article about red maple, which is available to you as a member.

It is a real pain to have to worry about toxic plants, but it is just something that the responsible horse owner must do.
Member:
maribeth

Posted on Thursday, Nov 6, 2008 - 12:37 pm:

Thanks Vicki. My husband and I have done a little more study on the maple trees and it turns out they are silver maple which have the same elements of toxin as red maple but less. Sugar maple has this toxin as well and like the silver has less concentration of the toxin then the red. It is a pain to worry about the horses exposure to these plants and trees but they are worth it
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