When should I apply a preemergent herbicide to my lawn to control crabgrass?
The key to successful control of crabgrass in lawns is the correct timing of the preemergence herbicide application. Crabgrass seeds begin to germinate when soil temperatures reach 55 to 60 degrees F and continue to germinate over several weeks from spring into summer. If the material is applied too early, crabgrass seeds that germinate late in the season will not be controlled. Normally, preemergence herbicides should be applied in early to mid-April in southern Iowa, mid-April to May 1 in central Iowa, and late April to early May in the northern portion of the state. The timing of the preemergence herbicide application will vary somewhat from year to year because of weather conditions. However, events in nature generally occur in a natural sequence. Preemergence herbicides should be applied when the forsythia blossoms start dropping or when redbud trees reach full bloom. Crabgrass seed germination typically begins after these events. When should I cut my potato tubers into sections p
