2,4-D
Rate 1.5 to 2 lb ae/A
Time Apply after tilling 3 to 4 inches deep and when regrowth is 4 to 6 inches tall.
Remarks If not tilled, treat in spring and fall. Two to three annual re-treatments may be needed for complete control.
Caution Avoid drift to sensitive crops.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
picloram (Tordon)
Rate 1 lb ae/A
Time Apply when plants are fully leaved and actively growing.
Caution Most formulations are restricted-use herbicides. See label for grazing restrictions. Do not contaminate water. Potatoes, beans, and many other crops are very sensitive to picloram. Do not use in diversified cropping areas. At rates above 0.5 lb ae/A (1 quart/A), apply only as spot treatment not to exceed 25% of a landowner's acreage in a given watershed in a single season.
Site of action Group 4: synthetic auxin
Chemical family Pyridine