2,4-DB (Butyrac 200)
Rate 0.5 to 1.5 lb ae/a (1 to 3 quarts/a Butyrac 200 or Butoxone 200)
Time Apply postemergence to small seedling weeds less than 3 inches tall, and when alfalfa seedlings have two to four trifoliate leaves.
Remarks Controls broadleaf weeds only, not grasses. Use higher rate in low-humidity areas. Using 2,4-DB is progressively more damaging to alfalfa as it matures. Certain annual broadleaf weeds such as smartweed, prostrate knotweed, redroot pigweed, and chickweed are resistant.
Caution Do not graze seedling alfalfa within 60 days after application.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
bromoxynil (Buctril 4EC)
Rate 0.25 to 0.375 lb ai/a (0.5 to 0.75 quart/a) or 0.5 lb ai/a (1 quart/a) when applied through sprinkler irrigation
Time Apply in fall or spring when alfalfa has at least two trifoliate leaves, and when weeds listed as susceptible or moderately susceptible have no more than four leaves, and are no more than 2 inches tall or 1 inch wide.
Remarks For broadleaf weeds only. Crop may be stunted temporarily, but yields should not drop.
Caution Do not treat when temperature exceeds or is expected to exceed 70°F in the 3 days after application by ground, or exceeds 85°F if applied through sprinkler irrigation systems; crop injury may be unacceptable. Do not add a surfactant or crop oil because crop injury may increase. Do not cut for feed or graze for 30 days after application.
Site of action Group 6: photosystem II inhibitor
Chemical family Nitrile