|Scientific Name||Setaria viridis (L.)Beauv.|
|Common Names||English: Giant green foxtail, green bristlegrass, green bristle grass; German: Grüne Borstenhirse; French: Sétaire verte; Spanish: Almorejo|
|Description||Annual, tufted warm season grass, closely related to cultivated Setaria species for grain and forage use, originates from Eurasia.|
Mature spikelets fall entire, leaf sheath and leaf blade virtually glabrous, green at the youth stage, during maturation red.
Youngest leaf is rolled.
Leaves about 20 cm (2 - 40 cm) (0.78 - 15.74 inch) long by 10 mm (4 - 25 mm) (0.147 - 0.98 inch).
Leaf-blade surface scaberulous; glabrous.
More-or-less erect, thin and hairless up to 70 cm, rarely 100 cm (27.55 inch, rarely 39.37 inch) high.
Leaves wide, flat, acuminate, light green, sometimes reddish-purple, drooping, distinctly but finely veined with prominent mid-vein below (keeled), mid-vein white or light green, scabrous above, usually glabrous below.
Ligule a fringe of hairs up to 2 mm (0.078 inch) long, fused at the base.
Sheaths slightly compressed, sometimes purplish at the base, the margins noticeably ciliate.
Dense spike-like panicle inflorescence, erect or slightly nodding at the tip, rachis often pilose.
Spikelets in very short panicle branches, each spikelet elliptical, subtended by 1 to 3 bristles 5-10 mm (0.19 - 0.39 inch) long, usually green, rarely purple, antrorsely barbed.
Lower glume smaller than spikelet, upper glume 5-6-nerved.
Lower lemma sterile, like the upper glume, upper lemma fertile, finely rugose.
Summer-early autumn, flowering after 26 days growth in an 8-hour photoperiod, after 62 days in a 16-hour photoperiod.
Very finely transversely wrinkled or ridged.
Germination in late spring, emerges later than Echinochloa crus-galli. Freshly shed seed is germinating immediately. Optimum temperatures for germination are 20 - 25 °C (68 - 77 °F) and most germination occurs from the top 1 - 2 cm (0.39 - 0.78 inch) soil layer.
Viability Of Seeds
Seed viability up to 40 years.
Seeds are propagated by contaminated crop seeds and by animals. The weed is able to tiller and to produce seeds within 2-3 months.
Temperate and subtropical zones.
S. viridis prefers light and coarse-textured soils, all soils including black clays. It is favored by high nitrogen levels.
Additional Crop Information
Also in gardens, cereals, vegetable crops, ornamentals, grassland and forestry, waste places, disturbed areas and along roads.
Individual plants cause only moderate yield reduction, however, S. viridis often occurrs in high densities. It can escape control by late emergence after herbicides had been applied.
Integrated Crop Management
Rotations with winter annual crops or cover crops, mechanical weed control methods have only limited success.
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