From Purdue Turf: In theory, a barrier of preemergene herbicide is created in the soil and limites emergence of crabgrass. Any gap in this barrier could allow crabgrass to germinate. This is why a uniform application of preemergence herbicide is required and practices like power raking or aerification are usually not recommended after application. However, research consistently shows that aerification does not reduce effectiveness of the herbicide. When aerification plugs are returned to soil, the herbicide may be simply redistributed in soil and not actually removed. The size of an aerification hole is only 0.5 to 0.75 inche in diameter and even though a crabgrass plant may germinate in a hole, its roots will explore well outside that hole and come into contact with the herbicide. Our recommendation is to not tempt fate and limit aerification following preemergence herbicide application if possible. But if turf areas will benefit long-term from aerification, aerify whenever you can regardless if a preemergence herbicide has been applied. Here is a link that might be useful: Purdue Turf Tip

Hmm. First comment, I'm not getting e-mail when someone posts. Second comment, Must mean that regular grass grown long will shade out the goose grass? Third commment, it's not goose grass! Now I have to identify it. Maybe I can post or link a pic? Thanks

Picture of goose grass in my yard before applying Specticle G.

Both crab grass and goose grass are summer annuals and they germinate from seeds that are on the soil when temperatures have warmed. Both have a somewhat prostrate growth pattern, although the seed heads of goose grass may grow more upright than those of crab grass do. Goose grass is also known as wire grass, because the grass blades tend to be thinner (more wire like) than those of crab grass. Once you yank out a clump of either of these grasses that clump will not regrow, but other seeds in the soil may germinate and grow in its place. There are poisons that you can use on each clump as it appears but they will also kill the more desirable grasses leaving holes for more of these undesirable grass to grow. kimmq is kimmsr