Poast is very good for controlling grass in clover. Butyrac can kill broadleaf weeds in clover. Mowing the weeds a few times during the summer will help a lot as well.

It can be tough to control weeds in sweet corn. Atrazine is good if you can use it, and if you can get it (tends to be restricted use). Other options are 2,4-d for broadleaf weeds, prowl/lasso are good if you can get them on before the weeds germinate.