Following populations of biostimulants in casing soils

Wageningen University & Research is a partner in the BIOSCHAMP project, in which a low-peat biostimulant casing for the button mushroom industry is developed. Supplement of biostimulants to casing is considered to increase productivity and suppressiveness against important mushroom pathogens that can be present in the (low peat) casings.

To optimize the biostimulant treatment and to evaluate the efficacy of the treatment, it is important to follow the populations of supplemented biostimulants in the casings. For this, specific detection methods are required. In Wageningen the assays were developed and the population dynamics of the biostimulants studied.

As biostimulants, bacteria were used, selected by the University of Oxford, one of the partners in the project. A Pseudomonas strain were chosen, able to stimulate productivity in small scale mushroom cultivation experiments. In addition, a Bacillus strain was used, able to inhibit important mushroom pathogens in a plate assay, such as those causing the cobweb disease and green moulds.

"To detect the Pseudomonas and Bacillus strains, specific molecular assays were developed, able to quantify the bacteria in the casings." - Jan van der Wolf

In a mushroom cultivation facility in Wageningen, experiments were conducted with the biostimulants in different casings. The Pseudomonas or the Bacillus strain was sprayed in a high dose on the casing after which the populations were followed. Treatments with water served as a control. Samples were taken from the casing at important moments of the mushroom cultivation. DNA was purified from the samples and tested in the molecular assay.

These studies have been helpful to get a better insight in the potential of biostimulants and measures to improve the efficacy.