Yellow Bristle Grass - The Ute Guide

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Biology Yellow Bristle Grass Ute Guide As a summer growing annual, yellow bristle grass reproduces only by seed. Seeds are dispersed by water, soil movement, animals, and as contaminants of crop seed and hay. The barbed seeds are often carried in fur, feathers, or clothing. Seeds are hard-coated and most fl oat on water. Seed production and germination requirements are variable, depending on several factors, including environmental conditions. Optimal temperatures for germination are typically between 20 and 35°C. Germination typically starts in mid October and peaks in mid November. Early seed heads appear in mid to late December but mostly in January and February. Mature plants and empty seed heads will persist until the fi rst frost. Yellow bristle grass seeds are usually dormant at maturity and require about 2–4 months of after-ripening before they can germinate. Most seeds survive only a few years under fi eld conditions, although some deeply buried seed may survive for up to 10 years or more. Seedlings can emerge from soil depths of up to 10 cm, but optimal germination is at 1–2 cm depth. Counts have shown seed numbers up to 20,000/m 2 but typically 5–10,000/m 2 under light infestations. 6
Yellow bristle grass occurs in areas with adequate summer rainfall, usually where the annual rainfall exceeds 500 mm per annum, although it can tolerate dry conditions once established. It grows in areas where the soil has been disturbed, including cultivated areas, old pastures and along footpaths and the side of roads, especially where water collects. Yellow bristle grass has a C 4 photosynthetic pathway so it grows best at higher temperatures and is frost tender. It is not toxic to stock but they might avoid grazing the seed head. Yellow bristle grass fi lls a similar environmental niche to other C 4 summer annual grasses such as crowfoot grass, summer grass and smooth witchgrass. However, due to the bristly nature of the seed it is more readily spread than the other species. It is moderate to slow-growing, especially if the weather remains cool, and generally should not establish and compete in vigorous ryegrass/white clover swards. Yellow bristle grass establishes in run-out or damaged pastures that have been opened up due to pugging, over-grazing or the death of winter annuals such as fl at weeds or annual poa. Yellow Bristle Grass Ute Guide 7
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Page 7 and 8: Preface The Yellow Bristle Grass Ac
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Page 17 and 18: Emerging leaf Blade base Blade Shea
Page 19 and 20: Characteristics: Emerging leaf roll
Page 21 and 22: Characteristics: A perennial grass
Page 23 and 24: Characteristics: Emerging leaf fold
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Yellow Bristle Grass - The Ute Guide

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