Botanical name: Lolium rigidum
Common Names
Wimmera ryegrass, ryegrass
Annual ryegrass (Lolium rigidum) is one of the most serious and costly weeds of annual winter cropping systems in southern Australia. Annual ryegrass is highly competitive and can compete with a crop as early as the two-leaf crop stage. It is a winter to spring growing weed that can emerge from late autumn through to early spring. The number of emergence flushes and the density of plants that emerge are related to initial seedbank levels and the frequency and amount of rainfall.
Annual ryegrass is hairless and has bright green, narrow leaves. The leaves are shiny, especially on the back of the blade. It has a wide ligule, long auricles and the emerging leaf is folded. The base (below ground) is often reddish purple in colour and seedlings exude a clear sap when crushed.
Mature plants are erect and up to 900 millimetres (mm) in height. The inflorescence (flowering stems) are flat and up to 300mm in length. Spikelets have 3-9 flowers and the husk is almost the same length as the spikelet.
Seeds are relatively flat, 4-6mm long, 1mm wide and straw-coloured, with the seed embryo often visible through the outer layers. They are held securely to the flower stem and significant force is needed to detach them either as individual seeds or as part of the flower stem.
SIMILAR SPECIES
Very similar to Tall Fescues, also known as Festuca Grundinacea.
SCENARIO AND SOLUTION:
- In couch lawns: use Coliseum.
- Any other scenarios: spot spray with Apparent Glyphosate or Gryphon Glyphosate 450 Herbicide.
Reference: https://www.agric.wa.gov.au/grains-research-development/annual-ryegrass
