During fermentation, Serenade ASO's beneficial bacteria produce a range of anti-fungal biological compounds including a group kown as lipopeptides. The lipopeptide profile of this biological chemistry is unique to the specially selected strain of Bacillus in Serenade, QST 713, and is not shared by other B. subtilis or B. amyloliquefasciens strains found in alternative products.
For foliar uses, the lipopeptide component of the biological chemistry is most important. On contact, these lipopeptides disrupt the cell membranes of the pathogen, resulting in physical breakdown of its cells. This mode of action is unique to fungicides based on B. subtilis and B. amylioquefasciens strains and is recognised by the Fungicide Resistance Action Committee (FRAC) as Code 44.
Serenade ASO actively colonises roots, forming a protective physical barrier against soil diseases, such as Pythium spp. This barrier grows along with the roots, resulting in extended periods of root protection. As a result, crops can benefit from enhanced plant health and higher marketable yields.
The different classes of lipopeptides within the biological compounds that Serenade ASO produces act on fungal pathogens in several contact-active ways. Serenade ASO is not systemic within the plant.
This membrane disruption mode of action is especially important when Serenade ASO is used alongside a second fungicide, as it may allow the second fungicide better access to the pathogen.
Once fungal diseases are established in a plant, contact-acting fungicides such as Serenade ASO often have insufficient curative activity to eliminate the pathogen. Preventative applications are therefore vital and application intervals of 7 days or less may be required to prevent fungal re-infection.
Systemic resistance to disease
Serenade ASO has been shown to induce systemic resistance responses in treated plants. In addition to contact control , it primes plants to defend themselves against pathogens. The induced response results in reduced disease and other measurable effects including activation of the salicylic acid (Systemic Acquired Resistance) and gibberellic acid (Induced Systemic Resistance) pathways - observed in both foliar and soil applications.
Because the MoA physically disrupts pathogen membranes, Serenade ASO has been shown to be active against a broad spectrum of diseases. In protected strawberries, Serenade ASO reduces fruit damage caused by Botrytis cinerea, but trials in this and many other crops also show useful activity against diseases such as powdery mildews, Alternaria and Sclerotinia.
Another group of biological compounds produced by Serenade ASO has been demonstrated to have efficacy against bacterial diseases including Clavibacter, Ralstonia, Erwinia, Pseudomonas and Xanthomonas species. Some of these compounds compete for an enzyme that pathogenic bacteria need to build their cell walls.
Serenade ASO is at inherently low risk for the development of resistance. As the major target is the cell membrane, no simple mutation can result in pathogen resistance. In fact, Serenade AO's multiple MoAs are great resistance breakers.
The beneficial bacteria in Serenade ASO form a mutual relationship with the plant in the root zone. The root exudates feed the growing bacillus biofilm, which in turn protects and promotes the plant's health through production of its many biological compounds.
Enhanced Root Structure
The colonisation of the roots by Bacillus subtilis not only produces anti-fungal, anti-bacterial and plant health stimulating compounds, but also produces plant growth hormones. These trigger enhanced root development, with visible increases in root laterals and fine root hair development and can speed early-season growth.
Improves nutrient mobilisation and uptake
Serenade ASO can improve nutrient solubilisation in soil, allowing plants more efficient access to essential nutrients like phosphate and potassium as well as the micronutrients manganese, calcium, boron, zinc and silicon. Improved nutrient availability within the plant following Serenade ASO applications has been seen to result in enhanced crop quality and shelf life of fresh produce.
Roots colonised by Serenade ASO are denser and have more lateral roots and longer root hairs. This increased root surface area gives improved phosphorus uptake, availability of nutrients, water absorption and anchorage - all leading to stronger, healthier plants.