Karen McDowell, PhD, from the University of Kentucky Gluck Equine Research Center, is an expert on tall fescue, having studied the plant for many years. Tall fescue is a type of grass that often has an endophyte fungus living on and in it. This endophyte produces a toxin, ergovaline, which can affect horses that eat it.

This video is the first in a series of three short presentations by McDowell on the topic. Here, you can learn about ergovaline, when and where it is found, and its seasonal fluctuations in pasture. McDowell also discusses how ergovaline can affect horses and what you can do to mitigate these effects.