Is poison lurking in your pasture?

A reader wrote,

"I have just spent the past seven months trying to keep a mare alive that had toxic poisoning. My vet tried everything, but in the end she had to be put down. We never discovered the source of the poison -- and there were other horses in the same pasture who were not affected.

"This is a problem everyone needs to know about," she concluded, "It would really help to know what to look for."

In response to this reader's concern and because all horse owners need to know what to look for, following are lists of toxic plants and trees and references for learning more.

Colorado State University's Dr. Anthony Knight, BVSc, chair of the Department of Clinical Sciences, lists the most poisonous plants for horses as: Bracken fern, Hemlock, Tansy ragwort, Johnsongrass/Sudan grass, Locoweed, Oleander, Water hemlock, Yellow star thistle/Russian knapweed and Yew. For a complete description of each plant, the dangers and signs go to www.Equisearch.com for "Ten Most Poisonous Plants for Horses."

Dr. Knight also lists trees that can be toxic to horses. Starting with the most hazardous he lists Yew, Oleander, Red Maple, Cherry, Black Walnut, Black Locust, Horse Chestnut, Buckeyes, Oak trees, acorns and Russian olive, also known as Oleaster.

Leaves from cherry, peach and plum trees can produce cyanide when wilted and can affect horses within a few hours of ingestion. To be assured that your pastures are safe, remove these trees or move the horses.

Learn more about toxic plants and trees at these helpful web sites: http://www.ces.ncsu.edu/copubs/ag/livestock/horse/002/ http://www.naturalhorsetraining.com/PoisonousPlants.html http://www.horsepresence.com/shop/DescBRPoisonPlant.html http://www.vth.colostate.edu/poisonous_plants/ http://www.ansci.cornell.edu/plants/horselist.html

The North Carolina State University Agriculture and Forestry Department lists 67 plants and weeds toxic to horses on the NCSU web site (see sidebar).

Southern States agronomist E.N. Garnett of Charlottesville, Va., reports that there is a rise of Perillia Mint this spring in the Albermarle County, Va., area.

Since poisonous plants vary according to geographic location, it's important to find out which ones exist in your area.

Consult your County Agricultural Extension Agent for help in identifying toxic weeds in your pasture.

Your Southern States dealer can assist you in selecting the proper horse-friendly herbicide for your pasture.