Which biofungicides are in our wheat septoria trials?

How to use biofungicides to manage septoria tritici in winter wheat is the subject of our new trials. Catherine Harries introduces the products under test and how initial observations suggest potentially promising results.

Earlier this year, we announced details of our pilot trials that examine biofungicides in commercial spray programmes.

In February, we published an article that covered the pilot’s basics, including:

• An overview of biofungicides, including the broad product types
• The status of biofungicide research and usage (with a focus on the UK)
• An overview of the trials, including how they’ve been set up

There are three trial sites:

• Hampshire (managed by Niab)
• Herefordshire (managed by ADAS)
• Lothian (managed by SRUC)

In these trials, we focus on septoria tritici because of:

• Its economic importance
• The availability of promising biofungicide products
• The relatively high number of preliminary research findings

To determine the products, the project’s steering group considered efficacy on septoria tritici and whether products were already at or near the market.

Table 1 shows the products currently under test in the trials that are authorised for use in wheat (although septoria tritici is not always a label target).

In addition, we are testing several products that are not currently authorised for use in any situation in the UK.

We have one unauthorised plant extract from the BM 01 mode of action (MoA) group, which disrupts fungal structures. Specifically, we are testing terpenes that aim to reduce the integrity of pathogens’ cell membranes.

There are two products based on living microbes (BM 02 group), which disrupt pathogen populations (e.g. via competition).

One of these is bacterial (Bacillus amyloliquefaciens), whereas the other is fungal (Pythium oligandrum).

The former has a label claim for septoria tritici reduction in cereals. On the latter, the cereal label target is fusarium head blight.

We have two elicitor products, which trigger or amplify natural plant defence responses (the P group).

The first is the natural compound laminarin (P 04), which is authorised to control a range of diseases in winter wheat (including septoria tritici). The second is based on potassium phosphonates (P 07).

Recently, a product containing potassium phosphonates and prothioconazole has been approved for use in wheat (and triticale). However, the straight product we have provides more flexibility in the trials, although it is not currently authorised.

To complete this year’s treatment list, we have some sulphur-based products.

Sulphur is a multi-site fungicide (M 02), which affects numerous biochemical reactions implicated in cell respiration. It is not strictly a biofungicide, but it is a naturally occurring substance.

For the authorised product, the label target is cereal powdery mildew. The other product (unauthorised) includes a synergist, which aims to enhance the activity of the sulphur component.

Table 1. Products authorised for use in wheat in the biofungicide trials (harvest 2026)

Table notes: Mode of action group and code are defined by the Fungicide Resistance Action Committee (FRAC). Until recently, Bacillus amyloliquefaciens was known as B. subtilis.

On 16 June 2026, I visited one of the three trials, which is at the same site as Niab’s open day in Hampshire (Sutton Scotney) and hosts one of our wheat fungicide performance trials.

The latter always promotes interesting discussion, but visitors were also extremely interested in the biofungicide trial.

As a result, Niab’s Aoife O’Driscoll (who works on the project) extended the tour to show the plots to those who wanted to see them.

As interest in alternatives to conventional chemistry is strong, the eagerness to use biofungicides, especially in lower-risk situations, is unsurprising.

The trials aim to answer one key question: is it better to add a biofungicide or increase the rate of the standard fungicide programme?

To provide an answer, we use a clever and relatively complex trial design.

This includes testing products alone and in combination with the base ‘conventional’ fungicide programme at a 50% field application rate.

We applied the treatments to two varieties with differences in septoria tritici resistance: a moderately susceptible and a moderately resistant variety.

With septoria tritici pressures generally low (including at this site), the results from the more susceptible variety will be particularly insightful this year.

When I visited, the conventional fungicide programme treatments appeared to be performing as expected.

Interestingly, some of the plots that only received a biofungicide looked cleaner than the untreated ones.

Similar treatment effects are showing in the moderately susceptible variety at the Lothian site in Scotland (see Figures 1 to 4).

We will need to wait for the complete assessment to be sure about treatment differences.

Certainly, there will be good results to present at the Agronomy Conference in December.

We will run more biofungicide trials next season, which will allow us to test the most promising products again but also include other products (potentially including seed treatments).

Figures 1 to 4 below show winter wheat treatment plot photos from a biofungicide trial site in Scotland (taken in mid-June), showing various levels of septoria tritici.

Figure 1. No fungicide treatment

Figure 2. Biofungicide treatment only

Figure 3. Same biofungicide with a base fungicide programme at a 50% field-application rate

Figure 4. Base fungicide programme at a 50% field-application rate