Glyphosate started to lose its effectiveness a few years ago so they started to try and find other herbicides that might work....2,4D is one of them. Enlist duo is a combination of Glyphosate and 2,4 D....I guess they'll to milk "round up" (glyphosate) for all it's worth before totally abandoning it. Just google 2,4 D and a ton of info will pop up.