2,4-D is your basic generic broadleaf weed killer found in most lawn weed killer sprays. You can buy gallon or 2.5 gallon jugs at most tractor supply or fleet farm type stores, in 40 to 60% concentrations.

Rather than spraying2 qts/acre ofglyphosate(roundup), you can use 1 qt glyphosate with 1/2 qt 2,4-D and get a faster/better kill at less cost.