Integrated Italian Ryegrass Control: Insights from Olde Appleton

The Agrii Olde Appleton Italian ryegrass trials centre in Yorkshire is helping farmers develop practical strategies to manage an increasingly resistant and problematic grassweed.

Working with host farmer Roger Mills, the site continues to generate valuable insight into cultural control, herbicide performance, and resistance management under real farm conditions.

Understanding the challenge

Established in 2019, the Olde Appleton trials centre was created when Agrii began searching for a dedicated ryegrass site to build on lessons learned from blackgrass management at the Stow Longa trials centre.

Background populations in the trial field were measured at around 400–500 ears/m², which was effectively wiping out the crop, explains Agrii Trials Manager Steve Corbett.

Host farmer Roger Mills believes ryegrass is becoming an even greater challenge than blackgrass on some farms.

“We’ve been talking about blackgrass for many years, but in my opinion, ryegrass is a bigger issue. It’s a beast,” he says.

The demonstration field contains varying ryegrass pressure, with particularly high populations in areas used for herbicide comparisons. Despite this, Roger says he has been encouraged by the level of control achieved in the trials.

“My advice to anybody seeing a few ryegrass plants on the farm is to take them out immediately. Pull them, glyphosate them or plough them down, don’t let them become established.”

Soil health and cultural control

The greatest impact on ryegrass management at North Hall Farm has come from adopting cultural control techniques refined through Agrii’s trials programme. Early discussions with Steve Corbett challenged assumptions about cereal establishment on the farm’s silty soils.

Soil organic matter has emerged as a key limitation. While farmyard manure could help improve organic matter levels, there is concern about reintroducing ryegrass seed to cleaned fields. Alternative approaches under evaluation include cover cropping and companion cropping.

According to Agrii Senior Trials Officer Justin Burton, the starting point in high-pressure situations is often reset ploughing.

“Then don’t be afraid to go back-to-back spring cropping, because one year may not do a good enough job. It’s about giving your main cash crop, often first wheat, the best possible chance,” he explains.

Cover crop management has also proved critical. Trials comparing destruction on December 30 and February 28 showed delayed destruction retained excess moisture in moisture-retentive soils, compromising spring barley establishment and reducing crop competitiveness.

“The ryegrass is winning in that situation because it is very happy growing at two inches deep and in waterlogged soils,” says Steve Corbett.

Herbicide resistance and programme design

The discovery of the first glyphosate-resistant ryegrass population in Kent has reinforced the importance of integrated weed management, says Agrii Technical Manager for Combinable Crop Trials Jodie Littleford.

The resistant population was identified in a no-till system where repeated glyphosate applications were made to surviving plants, a scenario that increases selection pressure.

Wider herbicide resistance remains a concern. Post-emergence contact products show mixed performance on UK populations, and there is widespread loss of sensitivity to key residual actives such as flufenacet.

This increases the importance of programmed herbicide strategies focused on reducing seed return.

“An additional 3% control on a programme delivering 90% control may not seem much, but it equates to roughly a 30% reduction in seed return when each surviving ryegrass plant can shed around 100 seeds,” Jodie explains.

Trial results from Olde Appleton

Trial plots were drilled on October 4 and received a pre-emergence programme of cinmethylin, pendimethalin and picolinafen applied on October 8. Moist seedbeds and cooler autumn temperatures supported strong pre-emergence activity.

“We recommend using cinmethylin first in the programme where possible. It has strong activity on emerging roots and shoots, but activity reduces once ryegrass plants begin to develop,” says Jodie Littleford.

Follow-up peri-emergence treatments were applied on October 30. A combination including the new active bixlazone, mixed with beflubutamid, delivered the strongest follow-up performance in the trials.

Bixlazone represents a new herbicide mode of action for cereals and shows particularly strong activity on ryegrass when used within a programme alongside complementary herbicides.

Building robust herbicide programmes is viewed as a long-term investment in field management, helping minimise seed return and maintain herbicide effectiveness across rotations.

Getting the best from residual herbicides

Application technique trials in 2024 demonstrated the importance of water volume, nozzle choice and adjuvant use. Comparing 200 L/ha and 120 L/ha spray volumes alongside drift-reduction and flat fan nozzles revealed significant differences in performance.

At 200 L/ha, nozzle choice had little impact on efficacy, giving confidence that drift-reduction nozzles can be used without compromising performance. The addition of the adjuvant Backrow Max reduced ryegrass head counts from around 30 heads/m² to 10 heads/m².

Reducing water volume to 120 L/ha resulted in ryegrass populations of 80–90 heads/m², regardless of adjuvant use.

“Adjuvants are not a substitute for good application practice. Around 200 L/ha remains the benchmark for residual herbicide performance,” says Agrii Field Operations Specialist Gary Lander.

Top tips for managing Italian ryegrass

• Use the full suite of cultural controls including delayed drilling, spring cropping, cover crops and reset ploughing.
• Focus on reducing seed return to slow resistance development.
• Avoid repeated glyphosate applications on surviving plants.
• Apply residual herbicides at around 200 L/ha and consider adjuvant use where appropriate.