Large crabgrass

Large crabgrass

Weed Flora of Mississippi

Family: Poaceae

Genus: Digitaria         Species: sanguinalis

History: Native to Europe or Eurasia. It is believed to be one of the first cultivated grains and was brought to U.S. for use as a forage species. It was introduced into North America during European settlement. It occurs in both temperate and tropical climates and is currently distributed from 50° N latitude to 40° S latitude around the world.

Life Cycle: Summer annual

Special Characteristics: Genus’s name refers to ‘finger-like’ inflorescence. Prostrate or decumbent growth habit, adventitious rooting at nodes. Long, membranous ligule, stiff hairs on the leaf blade and sheath. Smooth crabgrass is similar, but sheaths and blades of this species are much less pubescent than large crabgrass. Crabgrass is lighter green than turf species, so they are obvious in lawns. Smooth crabgrass is generally smaller and lacks hair on stem and sheath.

Roots: Fibrous roots extend up to 6.5 ft deep.

Stem: Prostrate, spreading, branched, and rooting at the nodes. Mature plants have dozens of tillers; stems are 12 to 48 inches with erect central stems and sprawling outer stems with rooting at the nodes. Mature stems are flattened and red at the base.

 Leaves: True leaves are rolled in the bud and uncurl as they emerge. Ligules are membranous, translucent, and jagged. Auricles are absent. Stiff, erect hairs are present on both blade surfaces and on the sheath.

 Flower: Inflorescences are terminal, composed of up to 13 (usually 3 to 5) flat, fingerlike spikes arranged in a spiral near the stem tip.

 Seeds / Fruit: Seedhead consists of 3 to 5 spikes arranged in a ‘finger-like’ arrangement. Seeds are glossy, yellow­-brown, elliptic or lance shaped. Seeds are dormant when shed from the parent plant but gradually lose dormancy over a period of several months.

Interference: Large crabgrass is a bigger problem in agricultural fields in the southern U.S. than in the Cornbelt due to warmer spring temperatures in the South. Large crabgrass is a major agricultural problem due to its rapid growth, competitive nature, and prolific seed production, which can cause significant yield losses in crops like corn and soybean. Large crabgrass management requires an integrated approach combining cultural, mechanical, and chemical methods.