Biofungicide product types and key considerations

Discover the main biofungicide groups and why products require careful integration in crop protection programmes.

Biofungicides are a type of biopesticide and are regulated as plant protection products.

They have been classified into several mode of action groups by the Fungicide Resistance Action Committee (FRAC).

Three are particularly relevant to UK arable crops.

These beneficial microbes may:

• Colonise plants and compete with pathogens for space and nutrients
• Produce compounds that inhibit pathogen growth
• Occasionally degrade fungal structures

The substances in this group may:

• Trigger or amplify the plant’s natural defence responses
• Enable a faster defensive response when disease arrives

Multi-site products, like naturally occurring sulphur, may:

• Act like a broad-spectrum protectant barrier on the plant surface
• Interfere with essential biological processes within fungal cells
• Prevent spores establishing and infecting plant tissue

Table 1. The characteristics associated with three biofungicide/natural substance groups

The following biofungicide groups are not currently as relevant to UK arable crops.

These plant-derived products are associated with several pathogen target sites, which include the ability to disrupt fungal structures. This group, with a BM 01 mode of action, includes several plant oils, such as tea tree oil.

Metabolites are associated with the substances that form following metabolic processes. It is also possible to create synthetic versions of natural metabolites.

This group, with a BM 03 mode of action, mainly targets cellular processes. At present, FRAC only cites cinnamaldehyde, which contributes to cinnamon’s flavour, in this group.

Biofungicides have been used most frequently in high-value horticultural markets.

Although they have good potential for cereal crops, clear guidance is needed to maximise their performance in crop protection programmes.

An AHDB pilot project is testing several products in replicated winter wheat field trials at multiple sites over two cropping years: 2025/26 and 2026/27.

The pilot trials focus on septoria tritici management, due to the economic importance of this disease, the availability of biological products with disease-management potential and a relatively high number of preliminary research findings.

The trials include tests of biofungicides applied as part of a conventional winter wheat fungicide programme and will assess the impact on disease levels and yields.

Do not expect biofungicides to perform in the same way as conventional fungicides.

Many conventional fungicides:

• Act directly on a specific biochemical target site in the pathogen
• Provide systemic or translaminar activity in the plant
• Protect untreated tissue and are active against early infections, in some cases
• Deliver relatively predictable disease control, when applied appropriately

Many biofungicides:

• Often rely on interactions between living organisms, the crop and its environment
• Those based on living organisms need to survive application, establish an effective population and successfully interact with the target pathogen before disease suppression occurs
• Act on or near the plant surface, often with little or no movement within the plant
• Need to activate plant defence responses
• Take time to develop activity
• Have lower levels of persistence, redistribution or curative activity as many conventional fungicides
• Can be overwhelmed in high-disease pressure situations

As microbial products are based on living organisms, they often need particular care to make sure they establish in sufficient numbers to effectively suppress pathogens.

The biological nature of these products often also leads to greater variability in product performance across crops, situations, locations and seasons.

Because of their sensitivity, biofungicides tend to work best when:

• Applied preventatively
• Applied at label timings
• Applied with other measures, as part of an integrated pest management (IPM) approach