crabgrasses

Crabgrasses are a group of warm-season grasses in the genus Digitaria that are commonly considered weeds in lawns, sports fields, and other turf areas. The term covers several species, most notably annual crabgrass (Digitaria sanguinalis) and smooth crabgrass (Digitaria ischaemum), with other creeping or perennial forms found in different regions.

Crabgrasses are typically low-growing and spreading, forming mats that hug the ground. They spread by stolons and short rhizomes and root at nodes that contact soil. Leaves are usually light to medium green, narrow, and can be several centimeters long. The seedheads are a distinctive feature, appearing as fingerlike spikes that project from the stem and can release large numbers of seeds, helping the plants spread rapidly in favorable conditions.

These grasses are adapted to warm temperatures and disturbed, sunny sites. They germinate in spring to early summer when soil temperatures rise and can quickly establish in thin or stressed turf. Most crabgrasses are annuals, completing their life cycle within one growing season, though some creeping perennials occur in certain climates. They are often most problematic in lawns where competition from well-maintained turf is reduced, such as after drought stress or poor management.

Management relies on an integrated approach. Cultural practices include maintaining a dense, healthy turf through proper mowing height, adequate irrigation, and balanced fertility to reduce bare soil and openings for establishment. Preemergence herbicides applied before crabgrass germination can limit new plants, while postemergence herbicides labeled for crabgrass control can manage established patches. Mechanical removal may help in small areas, but consistent prevention and turf management are key to long-term control.