Spotted spurge weed is an interesting plant because it is actually native to the Eastern U.S. but it spreads so quickly and ...

So, if you're applying pre-emergents after you've already spotted spurge growing in your yard, you're acting too late. Applying pre-emergents to sprouted spurge won't do anything to kill the weed.

March’s Weed of the Month, leafy spurge (Euphorbia esula) is an invader of pastures, forage, grasslands, and ditches. It is native to Eurasia and has become widespread throughout the United States.