Smith' s new grazing land consists entirely of fescue grass  Half of the grass contains a species of fungus that makes cows ill when they eat it
Smith' s cows will most likely learn to graze exclusively on the grass that does not contain the fungus, since, like many other animals, cows will avoid eating a patch of grass if they sense a substance in it that has made them ill
The fungus that is contained in the fescue grass cannot be eradicated without destroying the grass itself.