These weeds are translocating their carbohydrates upward to the leaves at this time. Herbicide applications will burn off the shoots but may not kill the root system. Power raking is a mechanical method of thatch control. Power raking can damage the turf and preemergence crabgrass herbicides should be applied after raking and thatch removal. On the other hand, core aerating the lawn will help the thatch to naturally decompose.
Aeration is also less damaging to the grass.
Iowa State University , Ames, Iowa. This information subject to a usage policy .