Which are the principal species of crabgrass?

• A. Digitaria sanguinalis and Digitaria ischaemum.
• B. Setaria viridis and Setaria glauca.
• C. Rumex crispus and Rumex altissimus.
• D. Poa annua and Lolium perenne.

Answer: (A)

Crabgrass refers to two main warm-season annual grasses that you’ll see in turf management. The principal species are Digitaria sanguinalis, known as large crabgrass, and Digitaria ischaemum, known as smooth crabgrass. These two are the ones most commonly labeled and managed as crabgrass in lawns and sports turf. The other plants listed belong to different groups: Setaria species are foxtails, Rumex species are docks, and Poa annua plus Lolium perenne are annual bluegrass and perennial ryegrass, respectively. Recognizing that crabgrass consists of these two Digitaria species helps you identify the weed correctly and apply the right control timing and strategies, since crabgrass is an annual weed that responds to warm soil germination patterns and preemergent or postemergent treatments.