- Biological products are those with the basis of a living entity, e.g. bacteria or fungi.
- Beneficial effects may be due to:
- direct competition in the rhizosphere;
- compounds produced by the entity, such as antibiotic metabolites;
- induced plant resistance to pathogens.
- Naturally occurring Bacillus subtilis was first investigated at the end of the 19th century as a biological fertiliser. In the late 20th century it was developed as a seed treatment and research also indicated plant growth promotion effects. More …
- Use of Bacillus subtilis has been further investigated by an American research group, for efficacy against a range of diseases, however results varied with year, disease and application method (More …). Overall, B. subtilis sometimes resulted in significantly less disease than occurred in the untreated control, but this was not reliable.
- Initial research was performed on specific strains of B. subtilis. Other strains and species have been used in commercial products and effects vary between strains and species. Therefore it cannot be assumed that results from one product are applicable to others.
- Arbuscular mycorrhizal fungi (AMF) form associations with plant roots, which enable greater uptake of nutrients and water due to the extensive network of fungal filaments; in return the fungus obtains organic ‘food’ materials from the plant.
- Some commercially available AMF products are available, however their efficacy is likely to depend on the very specific composition of fungal / bacterial communities already present in the soil, and the exact composition of fungi in the product – and longevity will depend on agricultural practices, e.g. ploughing destroys mycorrhizal structures.
- Very good supporting evidence for specific products should therefore be sought.
- Use of these products in potatoes has not been examined by the PRG.
Management of natural communities
See Microbes section for concepts of managing natural bacterial and fungal communities.
Biological products notes
Biologicals 2019 (Summary of types of product available)
Biopesticides 2019 (Potential for use of biopesticides)
Biologicals 2017 (Comparison of Bacillus and chemical products; introduction to mycorrhizae)
Bacillus subtilis 2012 (Response to application of B. subtilis products)
Bacillus subtilis 2010 (Physiological effects of B. subtilis)
Further information on biological products
For information on products which have been tested by CMI see links included in: Biostimulant products.