What kind of preventer did you use? I used to use Scott's products, buying into the marketing tricks...this spring (mid-March), I applied Dimension from John Deere Landscapes/Lesco and the yard is still 99% weed-free. I applied at the heaviest rate listed, as we were infested with various grassy weeds and a nasty Hairy Bittercress outbreak. 4 months later, I'm impressed. I'd put another shot down shortly, but I need to overseed some areas. Great product for half the cost of Scott's.

I don't remember what I used but it was a name brand, not Scott's Where do you find the JD Dimension?? I have never seen it. I am willing to try anything

The only thing that will work post-emergent is something called Drive 75 DT - this product is normally only sold to lawn care companies and golf courses, and in fact, BASF doesn't even make it any more because they created a newer, much more expensive product they want to sell.

I found a site for you that has it on sale. Buy a pound to cover 1,000 sq ft of lawn. If you have more than that, buy it up now, as this product will disappear from the marketplace soon.

Todd

Here is a link that might be useful: Best Price for Drive 75 DT - Post-emergent Crabgrass Killer

The product that replaces Drive 75 is Drive XLR8, which is rainfast in 1 hour vs 6, and it is very effective at killing crabgrass at any tillering stage, unlike Drive 75.

XLR8 is a much better product than 75, the problem is that it cost twice as much.

Ortho Weed-B-Gon Max contains Quinclorac (Drive) for post-emergent crabgrass control, available at almost any big-box store and garden center.

The Dimension is available at John Deere Landscape stores, formerly known as Lesco. You didn't post where you're located, so there may not be one nearby.

Here is a link that might be useful: John Deere Landscapes