That is an interesting question.
My experience with a pre-emergent, called Quest for spraying around new tree seedlings, did a good job, but as the summer progressed, there were some 'strange' things that would pop up. Not sure what they were, but they were 'weed' like but not thick, like grass, so not a real problem. Milkweed is one that I remember, and thistle is another. Eventually when I stopped using quest, the grass did grow but probably not from seed.