Managing Toxic Pasture Plants

There are hundreds of plants in North America that
can be poisonous to horses.
Managing Toxic Pasture Plants - Articles


Poisonous plants contain toxins that generally have a bitter taste in order to keep the plant from being consumed. The animals are “trained” to avoid toxic plants by learning to recognize the smell or taste associated with the toxin. Fortunately, most healthy, well-fed animals will not eat toxic plants if they have access to good quality forage.

Livestock owners should learn to recognize toxic plants, and be aware of the symptoms they can cause. The level of concern should be the greatest when:

  • The animals are undernourished.
  • The animals do not receive adequate forage.
  • Pasture grasses are no longer available due to overgrazing, drought or changing seasons.
  • The plant is highly toxic.
  • The toxic plant has been reported to cause poisoning in healthy animals.

Plant poisoning can be difficult to diagnose, since symptoms can range from mild irritation to death. The severity of poisoning depends on how toxic the plant is and how much was eaten.

Almost every pasture contains some poisonous plants, or is bordered by trees or shrubs that are toxic. While it is not always possible to eliminate all of the plants that may be toxic, there are several ways of managing the plants and animals to reduce the possibility of poisoning:

  • Keep the animals healthy by maintaining a good nutritional program.
  • Make sure animals have a steady supply of forage (grass or hay).
  • Identify poisonous plants and trees in and adjacent to the pastures. Many good reference books, web sites, and fact sheets are available. Your local Penn State Extension office may have people on staff that can help you.
  • Remove or fence off toxic trees and shrubs.
  • Remove broken branches from toxic trees that have fallen into the pasture.
  • Do not plant trees or ornamental shrubs or plants near barns and pastures. Colorful ornamental plants are frequently toxic.
  • Do not use forest and wetlands for turn-outs. Many toxic plants grow in these environments.
  • Manage grasses to maintain a healthy, thick stand of grasses that can compete with weeds. Fertilize, rest, and rotate pastures when necessary.
  • Mow pastures to reduce weeds.
  • When necessary, eliminate toxic plants with appropriate herbicides.
  • Do not throw garden or lawn clippings into pastures.

by Donna L. Foulk, Equine Natural Resources Educator