Naar een betere benutting van het substraat : teeltmodel met compost : vervolgproef

De voedingsbehoeften van uitgroeiende champignons zijn onvoldoende bekend. Het doel van dit project is om in verschillende stappen te komen tot een modelsysteem waarin compost als een drager wordt gebruikt voor mycelium waaraan water en voedingsstoffen kunnen worden toegevoegd en waarmee makkelijker beluchtingen en temperatuurregelingen van substraat kunnen worden gerealiseerd

Kwaliteitsdiagnostiek champignons : eindverslag fase 1

In dit project om via gentechnologie ontwikkeling van instrumentarium voor betere voorspelling bewaarkwaliteit en kwaliteitsverloop van champignons is het kwaliteitsverloop van champignons vergeleken met de activiteit van een reeks genen in diezelfde champignons. Met de verkregen resultaten lijkt de eerste stap gezet te zijn voor het ontwikkelen van een snelle toets waarmee het kwaliteitsverloop van champignons voorspelt kan worden op moment van oogst en vlak na de oogst. Tussen champignon batches met een goed en slechte kwaliteit blijken genen te verschillen in activiteit. Deze activiteitsverschillen zijn al te zien op het moment van oogst. Op dat moment zijn er met het oog nog geen kwaliteitsverschillen te zien of correleren met het oog zichtbare verschillen niet met de kwaliteit na een week gekoelde bewaring. Het is nu zaak om het aantal genen dat nodig is voor een betrouwbare voorspelling verder terug te brengen en te valideren. Met deze gereduceerde set kan dan een betaalbare praktijktoets ontwikkeld worden. De opgedane kennis is bruikbaar in de veredeling en kan misschien uitontwikkeld worden als een hulpmiddel bij het sturen van de teelt op kwalitei

Nieuwe inzichten in de ziekteverwekkers van bacterievlekken

'Weerstand van de dekaarde tegen bacterievlekkenziekte' is een project bij Wageningen University & Research (WUR), dat wordt uitgevoerd in samenwerking met verschillende leden van de Nederlandse toeleveringsketen voor champignons. Over een periode van vier jaar heeft dit project een breed scala aan vragen over bacterievlekken bij champignons beantwoord. Zo is kennis verzameld over de identificattie van de veroorzakers, detectie van de ziekteverwekkers, infectiedynamiek, bron van introductie, het effect van verschillende soorten dekaarde en de weerstand van dekaarde tegen bacterievlekken. In deze bijdrage vatten we de belangrijkste bevindingen van het project samen

Identification, diagnostics and infection dynamics of bacterial blotch pathogens

'Casing soil resilience to bacterial blotch' is an ongoing project at Wageningen University & Research (WUR), running in collaboration with various members of the Dutch mushroom supply-chain industry. Over the course of four years, this project has answered a broad-range of questions about bacterial blotch diseases of mushrooms. Research was done to generate knowledge on the identification of the causative agents, detection of blotch pathogens, infection dynamics, source of introduction, effect of different casing soils, and casing soil resilience to blotch outbreaks. Here we summarize the most significant findings from the project

Circular alternatives to peat in growing media: A microbiome perspective

Peat use in horticulture is associated with a large ecological footprint. Peat is the predominant growing media in Europe. Modern cropping systems rely heavily on dynamic interactions of the crop with the microorganisms in the growing media and yet, in the search for sustainable peat-alternatives, the microbiome of the growing media has often been ignored. In mushroom cultivation, peat is a prime determinant of productivity, in the form of a casing soil which supplies beneficial microbes. In this study we describe the microbial composition, interactions, and activity of four circular substrates used to proportionally replace peat in mushroom growing media. We also evaluate various physico-chemical characteristics of the peat-alternatives. We characterize the impact of sanitary pre-treatments such as steaming and acidification on the microbiome as well as the agronomical performance of the peat-reduced growing media. We found that grass fibres from agricultural residue streams, peat-moss farmed in degraded peatlands, and spent casing soil recycled from previous cultivation cycles can be used to successfully replace peat in mushroom growing media. Peat moss and spent casing were expectedly similar to peat in physical, chemical, and microbiological properties. However, the grass fibres had unique characteristics, such as high organic matter content, low water holding capacity and a diverse and competitive microbiome. Pretreatment of the substrates by acidification and steaming significantly affected the microbiome, and reduced the presence of pests, pathogens and competitive fungi in the peat-reduced media. Strong trade-offs existed between the productivity and disease pressure in the circular cropping system, which are also governed by the microbial composition of the growing media. Knowledge on the accessibility, sustainability, and economic viability of these peat-alternatives will further determine the transition away from peat use and towards sustainable growing media

Comparative studies on the disease prevalence and population dynamics of ginger blotch and brown blotch pathogens of button mushrooms

Introduction: Bacterial blotch is one of the most economically important diseases of button mushrooms. Knowledge on mechanisms of disease expression, inoculum thresholds and disease management is limited to the most-well known pathogen, Pseudomonas tolaasii. Recent outbreaks in Western Europe have been attributed to ‘P. gingeri’ and P. salomonii for ginger and brown blotch, respectively, although information on their identity, infection dynamics and pathogenicity is largely lacking. Methods: The disease pressure in an experimental mushroom cultivation facility was evaluated for ‘P. gingeri’ and P. salomonii over varying inoculation densities, casing soil types, environmental humidity and cultivation cycles. The pathogen population structures in the casing soils were simultaneously tracked across the cropping cycle using highly specific and sensitive TaqmanTM-qPCR assays. Results: ‘P. gingeri’ caused disease outbreaks at lower inoculum thresholds (104 cfu/g) in the soil than P. salomonii (105 cfu/g). Ginger blotch generically declined in later harvest cycles, although brown blotch did not. Casing soils were differentially suppressive to blotch diseases, based on their composition and supplementation. Endemic pathogen populations increased across the cultivation cycle although the inoculated pathogen populations were consistent between the 1st and 2nd flush. Conclusion: ‘P. gingeri’ and P. salomonii have unique infection and population dynamics, that vary over soil types. Their endemic populations are also differently abundant in peat-based casing soils. This knowledge is essential to interpret diagnostic results from screening mushroom farms and design localized disease control strategies

Management of bacterial blotch: the casing, cultivar and more

Bacterial blotch diseases lead to coloured spots on the caps of mushrooms. This not only leaves the crop unmarketable, brt also reduces the post-harvest shelf-life of the crop. 'Casing soil resilience to bacterial blotch 'was a four-year research project at Wageningen University & Research, which described the role of the casing soil and cultivar on bacterial blotch outbreaks (see also MB102/2020). Here we summarize the newest findings together with suggested management strategies for blotch outbreaks

Casing soil microbiome mediates suppression of bacterial blotch of mushrooms during consecutive cultivation cycles

Shifts in the soil microbiome during continuous monoculture cropping coincide with increased suppressiveness against soil-borne diseases, as in the take-all decline of wheat. Here we report a similar phenomenon for bacterialblotch of mushrooms, caused by Pseudomonas ‘gingeri’, where ginger blotch incidence decreases during consecutive cycles of mushroom cultivation. We explored the infection dynamics of blotch during consecutive cultivation cycles for different casing soil mixtures. We also observed the population dynamics of the pathogen in these casing soils. In addition, the composition of the casing soil microbiome was compared between blotch suppressive and conducive soils. Finally, we studied the transferability of blotch suppressiveness. A consistentdecline of bacterial blotch was observed for two consecutive cultivation cycles of mushroom cropping, across ten casing soil mixtures composed of different peat sources and supplements. Blotch suppression occurred without reduction of pathogen populations in the casing soils. Aqueous extracts made from suppressive soils were able to reduce blotch incidence in conducive casing soils, indicating that blotch suppression is transferrable and microbially mediated. Changes in the microbial community composition of the casing soils reflected pathogen invasion, pathogen establishment and disease suppression, in addition to the expected temporal changes across the cultivation cycles. Specific bacterial genera were associated with soil suppressiveness to bacterial blotch, such as, Pseudomonas sp., Dyadobacter sp., Pedobacter sp., and Flavobacterium sp. We suggest that the suppression of bacterial blotch is induced due to high pathogen populations in the first cultivation cycle, and mediated by inhibition of virulence factors such as those controlled by quorum sensing in the later cultivation cycles

Browning sensitivity of button mushrooms

To study the sensitivity of Agaricus bisporus mushrooms to bruising, a reproducible method was developed to apply mechanical damage to mushroom caps and quantify the subsequent discoloration. The newly developed bruising device can apply damage to the cap tissue of intact button mushrooms by a slip-shear sliding process in a fast and reproducible way. A protocol has been developed to obtain the most reliable and reproducible method to compare bruising sensitivity of different A. bisporus strains. The severity of the bruise is quantified with a computer image analysis system. Pictures of the bruised mushroom caps were taken under controlled lighting conditions and calibrated to a local reference. Image analysis software was developed to calculate the whiteness index (L-(3xb*), as defined by Hunter). This method of bruising and image based quantification was subsequently applied to a collection of wild, commercial and hybrid A. bisporus strains. A significant difference was found between bruising sensitive mushrooms and bruising tolerant mushrooms. A correlation was found between discoloration by the bruising device and discoloration caused by transportation of mushrooms on a conveyor belt. Less correlation was found between post-harvest discoloration of undamaged stored mushrooms and the bruising device. This indicates that discoloration caused by bruising or by storage of intact mushrooms might have different mechanisms