How to tackle the increasing problem of Italian ryegrass

Good crop rotations and cultivations are two critical factors in controlling troublesome Italian ryegrass in arable crops, in tandem with a good residual herbicide regime.

These two cultural control methods, often involving spring cropping and rotational ploughing, will help in the fight against this aggressive, yield-sapping grassweed, which can germinate from August until the ­following June.

See also: How a farmer is planning weed control without flufenacet

Italian ryegrass is an annual grassweed, like blackgrass, so preventing it from heading and shedding seeds is key, and cultural controls are likely to take centre stage as it becomes an increasing problem on arable farms.

Additionally, the grassweed has shown resistance to glyphosate in some fields, while there are signs of reduced effectiveness of the widely used residual herbicide flufenacet, which may be banned in the coming years.

Jack Poulden, research trials agronomist at crop consultant Niab, says Italian ryegrass seeds mature very quickly in late May and early June to exacerbate any existing weed burden, so a clear control strategy is needed.

“Growers need a long-term campaign across the rotation to counter Italian ryegrass. It is a war rather than an individual battle,” he tells Farmers Weekly.

Italian ryegrass has become more of a problem on some arable farms as it can be introduced by seed spreading through muck-for-straw deals and on silage machinery moving between farms.

Control is broadly similar to blackgrass in terms of cultural controls, but the problem is more acute due to Italian ryegrass’s longer germination period. It can germinate throughout the year apart from in the very driest months of the summer.

Any cultural control technique that is effective against blackgrass also works for Italian ryegrass, although not as well due to its long germination.

Spring cropping

In terms of crop rotation, Jack says spring cropping has a key role to play to create good flushes of ryegrass, which can be controlled by cultivations or judicial use of glyphosate.

Choice of spring crops can be crucial. If a field has a large population of ryegrass seed at depth, then maize or spring barley will be better than sugar beet, as the first two will likely result in less soil disturbance at depth which may bring up deeply buried seed.

Cultivations can play a big role in control, and rotational ploughing has been shown to give good control, but growers need to understand where the weed seeds are in the soil profile before turning to the plough.

Jack suggests growers take soil samples at different depths in a field, and then look at what germinates when seeds in these samples are allowed to germinate in soil trays in a warm greenhouse.

Understanding the weed seed profile in soils before starting rotational ploughing is critical. If the seed is deeply buried then ploughing will only bring it to the surface, while seed in the top layer can be buried and then left undisturbed by subsequent shallow cultivations.

Other cultural approaches

Other cultural methods have more limited use. Mechanical weeding can be useful but requires multiple passes due to its long germination period.

Topping the Italian ryegrass heads is another option but this proves challenging as there is only a small window when the heads are above a cereal crop.

David Jones, farm manager at Morley Farms, near Wymondham in Norfolk, is aiming to keep the grassweed under control with a multipronged approach on the light land farm’s 700ha of arable cropping.

“There is no one answer for control, there needs to be a combination of rotation, crop choice, cultivations and herbicides,” he says.

After assessing where the problems are – in terms of across fields or in patches and where the seed is in the soil profile – a strategy can be implemented.

Two spring barleys using shallow cultivations has shown to give good control on the farm, while maize has the advantage of being later drilling in the spring to allow more time to control grassweed flushes.

Maize, grown for silage or an anaerobic digestion plant, also allows different herbicides to be used from cereals to help in the control of the grassweed.

Herbicides

“Herbicide will always be part of the system, but they are not the full answer,” David says. He adds that flufenacet is a good herbicide for Italian ryegrass control, but the agrochemical is under threat, while other herbicides such as Luximum Plus, Defy, Proclus and Fundatis are useful for control.

Luximum Plus was launched in the UK in 2022 and Fundatis in 2025, and both contain actives with different modes of action to herbicides previously used to control grassweeds, thus helping with resistance management.

The return of oilseed rape into the rotation at Morley has helped with control, as the OSR herbicide Kerb (propyzamide) has shown good activity against Italian ryegrass, says David.

Weed experts say herbicide sequences are likely to be more effective than stacks due to the long window of germination, while herbicides with different modes of action will improve efficacy and resistance management.

All those speaking to Farmers Weekly were attending a recent AHDB Strategic Cereal Farm East meeting at the Morley Agricultural Foundation, a charity which operates Morley Farms, near Wymondham in Norfolk.

The farm consists of 700ha of arable cropping on light sandy loam soil.