One of the cultural practises used to control weeds in wheat fields is the application of 2,4-D sprays. The spray is applied as a post emergent selective after the wheat and the weeds have made some growth. The success of selective weed control in wheat depends upon the relative resistance of the wheat plants and the relative susceptibility of the weed plants to the 2,4-D spray. Major factors affecting successful weed control in wheat fields are the stage of growth of both wheat and weed plants, the quantity and formulation of 2,4-D applied, the solvent or carrier for the 2,4-D, the variety of wheat, and the species of weeds present.