When I built my North Carolina horse farm, I started with a field full of small pine trees, which was surrounded by a naturally occurring wind break. There was an incredible variety of trees and bushes around the edge. As I was considering what to thin out and what to leave hanging over the fence for shade, I found some poisonous plants I needed to remove if I wanted to be sure my horses stayed healthy. Here is a list for your reference:
Black Walnut Wild Cherry Domestic Cherry Black Locust Yew Red Maple Peach Plum Oak (Acorns are the problem) Horse Chestnut Oleander Mountain Laurel Rhododendron Azalea
If you know of others plants that should be added to the list, please let me know by contacting me at email@example.com, or leave a comment on this blog. Thanks!
By the way, I love some of the plants on this list, and I do have them around my home, but I have a secure fence and some distance between my horses and these plants.