Wietse de Boer

VolControl will examine the possibility to enhance control of soil-borne fungal crop diseases via stimulation of production of pathogen-suppressing volatiles by soil microbes. The working hypothesis is that these volatiles will be released by bacteria upon decomposition of selected organic materials that contain precursors of suppressive volatiles. During the first phase of the project, different organic materials will be screened and the ones that give the most promising results will be further tested for disease suppressing performance in greenhouse - and field trials. In addition, information will be provided on the identity of the produced suppressing volatiles and the microbes that release these volatiles. The project will be done in close collaboration with participating companies to optimize application perspectives

In AgriWood we examine the best strategies to stimulate saprotrophic fungi (fungi growing on dead organic materials) in arable soil. Most arable soils contain a very low amount of fungal filaments (hyphae). This is due to intensive tillage, use of fungicides and lack of degradable organic materials. The latter factor appears to be the most important one and, therefore, growth of saprotrophic fungi can be enhanced by feeding them. This can have several benefits, including the increase of natural disease suppression (intensification of competition between saprotrophs and pathogens), improving the efficiency of use of nitrogen fertilizers (fungi can store overloads of nitrogen), contribution to a better soil structure (fungal hyphae are involved in soil aggregate formation) and stimulation of a richer soil food web (increase of fungus-feeding micro- and mesofauna). Solid, carbon-rich materials are well suited to stimulate saprotrophic fungi and in our previous research we found that sawdusts of deciduous trees perform particularly well: rapid and long-lasting stimulation. More details on this research is available at: https://edepot.wur.nl/537032
In the current project, we examine the addition of sawdust in greenhouse- and field-trials to optimize the application strategies for different purposes (disease suppression, reduction nitrogen losses).

Nederlandse beschrijving van het onderzoek in: https://library.wur.nl/WebQuery/wurpubs/fulltext/545998

KNAW funded research on the role of biointeractions in causing fungal virulence in asparagus.

This project will investigate residue-stimulated atmospheric methane oxidation, and aims to elucidate its occurrence in field conditions, responsible microorganisms, underlying mechanisms and controlling factors.

This is a sub-project of a WUR-NIOO project entitled "Closing the loop: exploiting sustainable insect production to improve soil, crop and animal health", coordinated by Prof. Marcel Dicke. Insects can transform waste streams into high-value proteins for food and feed. Consequently, insects provide valuable contributions to a circular economy. The project aims to investigate the valorisation of the rest-stream of insect production, i.e. moulting skins and faeces (‘frass’) to enhance soil health and crop health (https://doi.org/10.1016/j.tplants.2022.01.007).
In the NIOO project, we study the decomposition rate of frass and moulting skins of three insects species (black soldier fly, mealworm, cricket) in arable soil as well as the composition of the fungal and bacterial decomposers. In addition, we study if the insect materials, which are rich in chitin, can be used to control soil-borne fungal plant diseases.

The long-term goal of the programme is to improve the livelihood of smallholder farmers in sub-Saharan Africa, by increasing the productivity of sorghum:

Since recently, Dutch farmers are required to grow cover crops in mixtures of at least two plant species.
In the Clever Cropping Project we investigated whether mixtures of cover crops have beneficial effects on soil microbiology and associated functions.
In long-term field experiments and laboratory incubations, we assessed emissions of greenhouse gasses and the diversity, abundance, and activity of microbial groups involved in environmentally relevant processes.
While in laboratory incubations we could clearly find increased beneficial microbial functioning associated with mixtures of cover crop residues, we could not observe this in a 5-year field experiment.
Overall, the use of cover crop mixtures did not have significant beneficial effects on soil microbial functioning but also no negative effects on for example greenhouse gas emissions.

The aim of the Saprofeed project was to enhance natural biocontrol of root-infecting pathogenic fungi in arable soils via stimulation of the growth of saprotrophic fungi (growing on dead organic materials). The basic idea, indicated in the picture, is that stimulation of saprotrophic fungi will lead to direct or indirect (via bacteria) competitive suppression of root-infecting pathogens.