The subject of this project is the production and application of fungal spores as biocontrol agent (BCA). The fungus to be used as BCA is Coniothyrium minitans, which is active against the fungus Sclerotinia Sclerotirorum. The ultimate goal is to provide farmers with a reliable pesticide against the plague. One important aspect of a marketable product is its shelf life. Spores, I stored under the right conditions, have a much longer shelf life than e.g. mycelium. Research would therefore be focused on the production of spores. Production of fungal spores is usually much better in number and quality when solid-state fermentation (SSF) is used instead of the more known liquid fermentation. A part off the project was devoted to the extension of the fundamental and applied aspects on SSF. Design rules were developed, following by scale up experiments. The behavior of the fungus under SSF conditions was determined and optimized. The integration of both approaches yielded an optimal process, which resulted in the efficient mass production of viable spores. This is of course of the utmost importance for the economic feasibility of the product.
The spores were tested, in climate chambers, glass houses and in the field, for their efficiency under various climatic conditions and on various crops. Aspects studied were time of application, dose, formulation, and way of application (on soil or leaves). It turned out that the dose needed to control the pathogen can be rather low. Under conditions of sufficient rainfall, a spraying dose of 250L/ha at the concentration of 5.10exp5 conidia/mL (10exp11 condia/ha) is a sufficient quantity of inoculum for adequate infection and thus reduction of survival of sclerotia of S.sclerotiorum. In combination with a limited effect of an exact germination percentage of the inoculum, this is promising for an effective and economically feasible biocontrol . With regard to the production system (SSF), our strategy and model, used to evaluate the production of concidia in a packed-bed reactor, can also be used to evaluate other SSF processes. A reactor has been constructed which will be used to validate the model predictions. Additionally, the project has resulted in process and technology scalable to industrial level. The technology used for the production at pilot scale, is a sterile reactor (50L) patented by one of the partners in the project (INRA. Dijon). Entirely controlled by a computer, it has permitted to produce approx. 2.5 10exp9 conidia per gram of defined solid medium (dry matter).