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Statewide IPM Program, University of California

Smutgrass  (Sporobolus indicus)

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Life stages of smutgrass Inflorescence Mature plant Seedling Mature plant in turf

Smutgrass is a tufted warm-season perennial grass that often invades irrigated pastures and turf areas particularly those with heavy grazing, foot traffic, or poor drainage. Sometime a black fungus called “smut” infects the flower clusters and upper leaves, hence the name smutgrass. This grass is found in the Sacramento Valley, northern San Joaquin Valley, San Francisco Bay region, Central Coast, South Coast, southern Peninsular Ranges, and elsewhere to about 3900 feet (1200 m). It is most problematic in southern part of the state.

Habitat

Smutgrass inhabits pastures (especially irrigated), ditches, turf, roadsides, crop fields, and other disturbed open places.

Collar

Ligules are a fringe of minute hairs. There are no auricles.

Mature plant

The mature plant grows in tufts up to 3-1/3 feet (1 m) long. Stems are round in cross-section, very tough and wiry, branched, fibrous at the base, and grow in a spreading to erect manner. Leaves are flat, rolled in the bud, have conspicuous veins, are hairless except for a few tiny hairs around the collar, and grow from 3-1/5 to 12 inches (8–30 cm) long and 1/8 to 1/5 inch (3–5 mm) wide. Sheaths are open and have intact or frayed, brown bases.

Flowers

Flowers bloom mostly from July through October, but will bloom as early as April where mild winters occur. Single flowers form clusters called inflorescences in dense spikelike or racemelike branches (panicles) that range from 4 to 20 inches (10–50 cm), but can grow to 31 inches (80 cm). They are often gray-green or purplish.

Seeds

The brown seeds are approximately 1/25 inch (1 mm) long. They become sticky when moistened. Seeds disperse from the parent plant with water, mud, or clinging to animals, shoes, tires, tools, and agricultural equipment.

Reproduction

Smutgrass reproduces by seed and usually produces many seeds.

Related or similar plants

  • Poverty dropseed, Sporobolus vaginiflorus

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