Italian rye-grass
Weed profile of Italian rye-grass (Lolium multiflorum). Discover growth habits, impact, and effective UK weed management strategies.
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.
| Auricles | Small |
| Leaves | Green and hairless, rolled in the shoot |
| Flowers | Each spikelet has multiple florets and is awned (long bristle-like tips) |
| Ligules | Short and blunt, 1-2mm |
| Number of seeds produced per plant | Up to 1000 |
| Seed shed | June to September |
| Germination period | September to November (94%), March to April (6%) |
| Germination depth | Up to 6cm |
| Primary dormancy | Variable, low |
| Does it have a secondary dormancy? | Transient |
| Seed longevity | 2 - 3 years |
| Factor promoting germination | light |
| Rate of seed decline with cultivations | 95% |
| Geographical location | Italian rye-grass is most commonly found in the arable areas of southern Britain where leys form part of the rotation. |
| Soil Type | This weed thrives in areas where there are high nitrogen levels in soils and a good drainage. |
| Rotation | Lengthen crop rotation to use alternative chemistry in different crops. |
| Impact | Italian rye-grass is competitive, a population of only 5 plants per m² will reduce yields by 5%. |
| Resistance risk | High. EMR is the predominant mechanism for resistance, although ACCase TSR and ALS TSR have been found in a few populations. |
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