Annual Broadleaf Weeds in Establishing New Stands

2,4-DB (Butyrac 200 or Butoxone)

Rate 0.5 to 1.5 lb ae/a (1 to 3 quarts/a Butyrac 200)

Time Apply postemergence to seedling weeds less than 3 inches tall. See label for size of alfalfa when treating.

Remarks Controls broadleaf weeds only. Use the higher rate in arid areas. 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 have proven resistant, especially under conditions west of the Cascades. Will not control grasses.

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)

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 spring or fall when alfalfa has at least four trifoliate leaves and weeds listed as susceptible or moderately susceptible have no more than four leaves or are no more than 2 inches tall or 1 inch wide.

Remarks For broadleaf weeds only. Crop may be temporarily stunted, but yield should not drop.

Caution Do not treat if temperature exceeds or is expected to exceed 70°F during the 3 days after application by ground, or exceeds 85°F if applied through the sprinkler; 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

bromoxynil (Buctril) + 2,4-DB

Rate 0.25 lb ai/a bromoxynil + 0.5 lb ae/a 2,4-DB

Time Apply in spring or fall when alfalfa has at least four trifoliate leaves.

Remarks For broadleaf weeds only. For improved control of tansy mustard, henbit, pigweed, and kochia compared to bromoxynil. Do not apply through a sprinkler. Follow the label for 2,4-DB. Crop may be temporarily stunted, but yields should not drop.

Caution Do not treat if temperature exceeds, or is expected to exceed, 70°F during the 3 days after application; crop injury may be unacceptable. Do not add a surfactant or crop oil because crop injury may increase. Do not graze or cut for feed for 30 days after application.

Site of action (bromoxynil) Group 6: photosystem II inhibitor; (2,4-DB) Group 4: synthetic auxin

Chemical family (bromoxynil) nitrile; (2,4-DB) phenoxy acetic acid