Butyrac / 2,4-DB
Chemical Name: 4-(2,4-dichlorophenoxy) butanoic acid
Chemical Family: Phenoxys
2,4-DB (POST)
2,4-DB (POST) on velvetleaf
Note epinastic bending of stems and petioles
2,4-DB (POST)
2,4-DB (POST) on broadleaf weeds
2,4-DB (POST) on velvetleaf, redroot pigweed, common lambsquarters, and wild mustard
2,4-DB (POST)
2,4-DB (POST) on soybean
WSSA Resistance Group: 4
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.
Symptoms: 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.
Residuality: None (short: <1 month).
Toxicity: Oral LD50 = 1960 mg/kg - moderately toxic.
Additional comments: 2,4-DB is herbicidally inactive.