Well, 2,4-D is good, but not that good. There are a lot of broadleaf plants it won't kill such as blackberry, clover and holly. Crossbow won't kill grass and is a good all around broadleaf killer. In my lawn I have used Weedmaster which is 2,4-D and dicamba and it has done a good job, killing clover and just about everything else but the grass--but it isn't too good on the blackberries unless you get the timing just right. And whatever you use, make sure you use a surfactant, which is a wetting agent to make the herbicide spread out across the leaves for better penetration. Makes a big difference. Especially important on plants with waxy surfaces on the leaves, such as poison oak--I don't know about poison ivy.
Also, be sure to mix according to the label, not just because you are supposed to but because that is the most effective concentration. For example, it you mix 2,4-D too rich, it will kill the top of the plant but won't translocate the chemical to the roots. Looks like it did a great job, but then the weeds come back.
