What a great name for a noxious lawn weed. Crabgrass can be so pervasive that it takes over entire sections of lawn. Sadly most good grasses do no spread, but each seed is one blade of grass and that's it. The only exception to this is soyza grass which has underground roots which spread and can cover entire areas.
Par of our backyard has suddenly become a stand of crabgrass, I'm not sure why all of a sudden this has happened. The main difference from other years is that we had a big Oak tree cut down in the spring but I'm not really sure why this would cause the crabgrass. The tree was on the edge of the yard, not in the lawn, but whatever the reason, this crabgrass is so thick it's hard to walk through.
So what to do? The experts tell us a couple of things. 1. You don't have crabgrass if you have a lush, thick lawn. The weed can't get a toehold in that case. We did have a thick lawn but I believe the heavy equipment brought in to take down the tree hardened the soil around it which kept the normal grass from coming back.
2. The best treatment is the pre-emergent week killers spread in the spring before they even begin to sprout. Too late for us.
3. Post-emergent weed killers are what we're looking at now. This is sprayed on after the crabgrass has come up. We'll be looking at a wide swath of brown, dead crabgrass for a while, but I plan to try this. For some reason crabgrass just keeps on spreading. The best products according to experts are: selective killers, meaning those which only damage the weeds.
The best crabgrass killer is Drive XLR8 but that is mostly legally sold to commercial lawn services. The next best for homeowners (with fairly successful results) would be Ortho Weed B Gon Max Plus Crabgrass Control.
The Ortho is what I'll try first.