Yesterday, I was called out to a lawn I had killed off spots of fescue in a predominantly bluegrass lawn and seeded(10 days after application of roundup). I seeded with a BG mix ot three varieties (I don't remember them exactly) The seed is in 3-5 leaf stage now....twelve weeks later. I seeded this lawn on 4-4-08...this was 6-26-08.... Is this because of a pre-emergent application or the relatiely cool 1st half of 2008.... This customer is not happy and I don't blame him. He also claims that "no one has been on their lawn period". The lawn is literally devoid of crabgrass and really any other weed for that matter. What do you think? What caused this?