2, 4 DB can't be metabolized into 2, 4 D in

2, 4 DB or 4-(2, 4-dichlorophenoxy) butyric acid is a selective systemic phenoxy herbicide used to control many annual and perennial broad leaf weeds.
2, 4 D is 2, 4-Dichlorophenoxyacetic acid is a systemic herbicide that kills most broadleaf weeds by causing uncontrolled growth in the weeds.
2, 4 DB cannot be metabolized into 2, 4 D in legumes. Whereas 2, 4 DB is metabolized to 2, 4 D in sensitive species as it is a herbicide. Some legumes that are sensitive to 2, 4 D are tolerant to 2, 4 DB because they lack the β oxidation activity required to activate it.