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Butyrac / 2,4-DB

Chemical Structure

Chemical Name:

4-(2,4-dichlorophenoxy) butanoic acid

Chemical Family:


WSSA Resistance Group:


Crop/non-crop registration:

Corn, seedling alfalfa, bird's foot trefoil, clover direct-seeded or underseeded in spring wheat, barley, oats

Sensitive weeds:

Small BLW (broadleaf weeds); top growth of Canada thistle, field bindweed, perennial sow-thistle.

Application method:

POST (some PRE).

Absorption & Translocation:

Absorbed through foliage and readily translocated via symplasm (including phloem) to growing points where it accumulates.

Mode of Action:

Disruption of transport systems and interference with nucleic acid metabolism.

Metabolic pathway inhibited:

Not completely understood;but similar to that of the endogenous auxin: indole acetic acid (IAA); specific site of action has not yet been identified.

Basis of Selectivity:

Susceptible species rapidly convert this product to the herbicidally active: 2,4-D. Tolerant species do not carry out this conversion.


Induces abnormal growth typical of growth-hormone herbicides ('epinastic bending'). Twisting, bending of stems and petioles; leaf curling and cupping and development of abnormal tissues and secondary roots. Plant death occurs from growth abnormalities - symptoms occur within hrs of application but death is a slow process: 3-5 wks.


None (short: <1 month).


Oral LD50 = 1960 mg/kg - moderately toxic.

Additional comments:

2,4-DB is herbicidally inactive.