Forage legumes are often injured when herbicides, such as 2,4–dichlorophenoxyacetic acid (2,4–D), are applied to control weeds in fields of grain containing legume seedlings. At times the legume seedlings are not injured materially but in many instances the herbicide applications result in a moderate or even drastic thinning of the stand. Various factors have been suggested to account for the variability in results observed.