Italian Ryegrass [Lolium multiflorum]

Italian rye-grass is an annual or biennial grass weed which can grow up to 100cm. Although not at the same levels as black-grass, Italian rye-grass is increasing as a weed problem in many areas of the UK. Populations are being made worse because of the build- up of herbicide resistance and large seed banks.

About the pest

Description

It is a leafy annual or biennial grass, 30 - 100cm tall. The stems are tufted or solitary with an upright or spreading habit and green hairless leaves. Italian rye-grass tends to be larger, stouter and more densely tufted than perennial rye-grass.

Key features

Plant: It is distinguished from perennial rye-grass by the leaves which are rolled in the shoot, and the large auricles.

Flowers: The lower bract is awned. Flowerheads are arranged at 90degrees to the flower stem.

Biology

Italian rye-grass is an economically important forage grass increasing as a weed problem in many areas of the UK. It can grow from seed or vegetatively from badly ploughed-in tufts, or rooting stems. Autumn-germinating plants can overwinter. It can become a severe weed in arable crops where pasture forms part of the rotation.

Symptoms & Diagnosis

Life Cycle

Seed longevity: >5 years

Seed weight: 2.5 mg

Seeds/head: 100

Treatment

Management

Use glyphosate in fallows, as a pre-harvest treatment and in break crops. Reducing seed spread by cleaning equipment between fields and avoiding using fields with heavy rye-grass populations will greatly decrease rye-grass problems.