Spring is off to a slow start this year but there are always questions regarding the optimum timing for applying crabgrass preemergence herbicides. There are several different methods used for determining the optimum application timing from tracking growing degree days (GDD) to looking for forsythia bush flower bloom. One system used by both professional turfgrass managers and do-it-yourselfers to determine application timing is to track GDDs using the website GDDTracker.
Read the full article by Kevin Frank, Michigan State University Extension, Department of Plant, Soil and Microbial Sciences.