Distribution and biology of perennial rye-grass in the UK

Perennial rye-grass is found throughout the UK and can be a weed of arable crops. Find out how to identify and control it.

Perennial rye-grass (Lolium perenne) can become a weed in arable crops where pasture forms part of the rotation. The plants remain green all winter and continue to grow. It flowers in early or late summer. Seeds germinate immediately on shedding, and stems can root.

• It is particularly competitive in winter wheat

It is a large, dark-green, glossy, tufted perennial grass, 30–60 cm tall producing flowering and sterile shoots.

Young plant: The backs of the leaves are shiny.

Fruit: The spikes have no awns.

Perennial rye-grass may be confused with rough-stalked meadow-grass when young. The flowerhead is similar to common couch but the spikelets of rye grasses are at 90 degrees to the stem while couch spikelets lie with their flattened side next to the stem.

Perennial rye-grass is found on a wide range of habitats, which may have been sown for grass, in meadows, pastures and on demolition sites. It does not grow above an altitude of 400 m.

It occurs on soils within the pH range 5–8.

• Seed longevity: 1–5 years
• Seed weight: 2 mg
• Seed/head or capsule: 100

Control with glyphosate in fallows, before break crops or as a pre-harvest treatment or with specific herbicides within crops. Clean equipment between fields to reduce seed spread.

For advice on herbicides, please speak with your agronomist or adviser.

When was this information last updated?

This page is based on content from the encyclopaedia of arable weeds publication. Since it was first released in 2008, the publication has been redesigned several times but not revised. However, it remains a good foundation for general information on the distribution and biology of weeds.