Dave, I have used both. Whether or not Gly4 isn't good at killing broadleaf weeds is up for debate IMO. It will depend on just what type of broadleaf weeds were talking about. I agree both Gly4 and 2,4,D used together is a better all around mix, 2,4,D alone will not kill grass and I have had it inhibit certain seedlings. If the Gly4 or whatever Glyphosphate you choose doesn't kill all the weeds the first time you spray, then I would spot spay the remaining hard to kill weeds a second time. I have not had any trouble killing some very tough broadleaf weeds.
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