The Spectator had an article about crabgrass this morning.
The only problem I have with this article is that it is from the McClatchy-Tribune Newspapers which is US based. The information about the pre-emergent crabgrass preventer doesn't hold true for Ontario. Not unless you've been headed to Buffalo, NY to shop for your lawn care products. http://www.torontosun.com/2011/08/21/some-head-south-for-banned-weed-killer
The only crabgrass preventer that is legal to use in Ontario is Corn Gluten Meal. This organic product will help reduce crabgrass germination, but it is not as effective as the banned product.