The herbicide 2,4-DB [4-(2,4-dichlorophenoxy) butyric acid] was not readily absorbed by peanut (Arachis hypogaea L.) leaves, was not accumlated in the nut at harvest and was very slowly metabolized to 2, 4-D (2,4-dichlorophenoxyacetic acid). In contrast, pigweed (Amaranthus retroflexus L.) readily absorbed the 2,4-DB and rapidly converted it to 2,4-D. The 2,4-D was subsequently translocated to the apical regions of the pigweed and resulted in severely reduced growth or death.

Applications of 0.9 kg/ha of 2,4-DB between maximum pegging and early pod (fruit) enlargement reduced yield and affected quality and pod size. Repeated applications of 0.45 kg/ha of 2,4-DB did not adversely affect the peanut. An analytical procedure sensitive to 0.1 ppm of 2,4-D and 0.2 ppm of 2,4-DB is described for analysis of fresh plant forage and nuts.