Developing guidance for wheat variety blends on UK farms

Research suggests that cereal variety blends (mixtures) can potentially deliver a range of benefits (compared to single-variety stands), such as:

• Increased yield and yield stability (across years and locations)
• Lessened disease severity
• Reduced fungicide spray intensity (saving costs and slowing the development of fungicide resistance)
• Prolonged durability of disease resistance genes

However, it is a complex area, which involves numerous genetic and environmental interactions (many of which are currently difficult to predict).

The uptake of varietal mixtures is increasing in Europe, most notably in Denmark, where winter wheat blends are now the most common ‘variety’.

The provision of yield, quality and disease data via its national variety trials provides farmers with the evidence and confidence to try blends. Additionally, Denmark enforces strict limits on fungicide use, which encourages the use of integrated pest management (IPM) to suppress disease.

In Denmark, most of the winter wheat crop is used for animal feed (about 90%). In the 2023/24 growing season, the first commercial winter wheat milling variety mixture was authorised (comprising varieties all individually approved for milling-wheat production), which will underpin the use of blends in this market.

Although there is some concern that grain from blends may fail to meet uniformity requirements of end-users, there is evidence that grain from mixtures can have equal or superior quality characteristics.

Interest in blends has increased in the UK, although no area information is available. The need for robust information on variety blends was identified in the most recent review of the AHDB Recommended Lists for cereals and oilseeds (RL).

Prior to the RL review, AHDB started activity in this area, introducing the variety blend tool for winter wheat in 2021, which adds value to RL agronomic data and uses pedigree information.

The relatively simple approach used in the tool can help identify three-way or four-way blends. However, it does not account for complementarity of traits of each variety in the blend (the data is from varieties grown as straights, not in blends) – in other words, it does not guarantee that a mix will be greater (or less than) the sum of its parts, but it can identify potentially useful mixes to trial.

What this project will deliver

Using the outputs of the variety blend tool and experience, this project will identify hard wheat milling varieties (UKFM Groups 1 and 2) to grow in dedicated variety blend trials, which will also feature the same varieties in single stands (for comparative purposes).

The two experimental sites are at:

• Harper Adams University in Shropshire (generally has a high septoria tritici pressure)
• Agrii Throws Farm in Essex (generally has a high yellow rust pressure)

A project steering group will help select the varieties to trial and provide guidance on trial protocols.

The sowing lists will be agreed annually and drilled each autumn (2025, 2026 and 2027).

The trials will include the following treatments:

• High-intensity-fungicide treatment: RL standard fungicide programme to suppress all diseases to test the additional benefits of blends*
• No-fungicide treatment: Untreated to test disease resistance of blends compared to their component varieties**

*Evidence suggests that strong blends utilise resources in different timings and spaces, which may contribute to yield and quality (e.g. protein) benefits.

**A fungicide at T2 (GS39) may be applied in severe disease situations to ensure the production of valid yield data (this would be defined as a low-input treatment).

Various measurements will be taken, including disease levels, canopy assessments, growth stages, height, yield and grain quality data, via milling and baking tests (assessed by Whitworth Bros) and an analysis of mycotoxins at Harper Adams University (including fusarium mycotoxins). The presence of ergot will also be assessed.

The results will help answer several important questions, such as:

• How should the variety blend tool be used to maximise its impact?
• How important is a greater genetic diversity in blends?
• How do blends perform relative to straight stands (and what are the reasons for the differences)?

The project will also improve and validate a genomic prediction model, which will use additional variety blend trial data supplied by Cope Seeds and Harper Adams University.

Cope Seeds will also talk with UK millers to gauge the opportunities and barriers associated with milling wheat blends (and how best to address them).

Project updates will be provided in annual reports (published on the AHDB website) and at open events at the project trial sites. Opportunities to present findings at other events, such as AHDB Strategic Cereal Farms, will also be explored.

In-kind contributions

• Cope Seeds (£5,000) – provides trial and commercial experience with varietal blends (and has strong links with millers)
• Wildfarmed (£5,000) – provides commercial experience with varietal blends (via its grower network)
• DSV United Kingdom (£7,500) – has a genomic prediction model for UK baking quality (currently for single varieties)
• Whitworth Bros – provision of milling and baking tests (at no cost to the project)

Providing answers to your questions

This research project was funded via a levy-payer-led commissioning process.