Dry Flowable Formulation of Biostimulants Trichoderma Strains

Abstract

Practical application of Trichoderma biostimulant strains requires biocompatible formulations, with an increased shelf-life. Dry flowable / water-dispersive granules are agricultural inputs formulations with an improved safety for environment and end-users. Due to their granular nature, such formulations do not produce dust and are less prone to absorb air humidity. Their lower variability on water activity reduces microbial contamination risks and enhances formulated microorganism survival. We developed a procedure for spray-drying alginate encapsulated high density conidia, with antioxidant protection. This spray-drying process assure a good survival of dried conidia and it is easy to be scale-up. We further formulate the resulting spray-dried flowable powder, using a CO₂ generating dispersant system, based on polyacrylic acid, citric acid and sodium bicarbonate, polyvinyl alcohol as adhesives and lecithin as wetting agent. Our proposed dispersant system avoids clump formation, which is highly possible on the formulated microorganisms, due to the hydrocolloid characteristics of dried propagules and of biocompatible adhesives, such as polyvinyl alcohol or carboxymethylcellulose. Physico-chemical characteristics determined for our formulation correspond with those established as standard for agrochemicals, demonstrating the compatibility of our dry flowable bioproducts with the usual application technology, spraying of pressurized diluted suspension of formulated products through nozzles. The biological activities, e.g. production of biological actives volatiles and degradation of lignocellulose material, of formulated biostimulant strains was maintained during formulation process and on dry flowable products stored for 12 months at room temperature.