National mushroom virus survey - update
The vast majority of mycoviruses – the viruses which are naturally widespread throughout both cultivated and wild fungi – cause no problems to their host. But occasionally, combinations of virus particles interact, causing quality and yield issues.
Pathogenic viruses can be hard to detect in mushroom crops. They can replicate unseen and undetected, establishing large disease reservoirs on-farm. Early symptoms can go unnoticed or be ignored. For example, sporadic brown mushrooms appearing in white button crops being dismissed as just ‘one of those things’.
The delay in identifying the causal ‘organisms’ was one of the key factors leading to the devastating impacts of MVX Syndrome in Europe. Early detection and appropriate intervention is key to successfully mitigating the effects of these serious pathogens.
Australia has a long history of virus disease. La France was first recorded in this country in 1969 and there have been sporadic damaging outbreaks recorded over the years.
In 2021 a farm reported a disorder expressing La France-like symptomology. However, samples sent to an external diagnostic laboratory did not detect the La France virus. A second sample was tested for Mushroom Virus X (MVX) Syndrome viruses. This test detected the AbV6 virus particle, which is associated with MVX Syndrome.
A preliminary survey of mushrooms from supermarkets, together with selected farm samples, provided results consistent with the findings from the farm outbreak samples. After consultation with Dr Helen Grogan (Teagasc in Ireland, the leading authority on MVX Syndrome), and discussions with the MU16003 project reference group, it was decided to offer a nation-wide survey to the industry to determine the extent of virus contamination in Australian button mushroom crops.
Read the full report from the Pest and Disease Team, Dr Warwick Gill and Judy Allan in MushroomLink Issue 2
It’s a wrap on MU16003 Pest and disease management and research services
Over the last five years, Warwick Gill (University of Tasmania) and Judy Allan have led the levy funded project MU16003 Pest and disease management and research services, creating an exhaustive and detailed body of knowledge for the Australian mushroom industry.
The team have researched and collated information on current and emerging mushroom pests and pathogens, as well as how to recognise, treat and manage them. They have also focussed strongly on communicating their findings through a variety of engaging formats. The legacy is an impressive and invaluable information resource.
Most of the resources created through the project are available via the AGORA website (agora.australianmushrooms.com.au, note that this is password protected), with a few highlights presented here.
Read more about their research highlights and top tips in MushroomLink Issue 1
It’s a wrap on MU16003 Pest and disease management and research services
Like all crops, mushroom yields can be adversely impacted by pests and diseases. However, mushrooms lack protective skins, as well as the defence compounds often produced by parent plants. Moreover, treating disease with fungicide is clearly problematic for a fungus! Added to this is a short cropping cycle, leaving little time to treat diseases mid cycle.
Prevention is better than cure very much applies here.
The team have researched and collated information on current and emerging mushroom pests and pathogens, as well as how to recognise, treat and manage them.
Research projects focussed on critical areas that would have the greatest impact on effective pest and disease management strategies, including:
Improving management of foot dips
Getting the best from cookout
Mushroom Virus X Syndrome - Patch Disease and Brown Cap Mushroom Disease
Syzygites megalocarpus – Troll Doll
Internal Stipe Necrosis
Grower engagement was a top priority over the five years, with considerable effort taken to encourage uptake of the resources and expertise that was being made available.
Despite COVID-19 disruptions, ten face-to-face workshops were delivered over five states, attracting attendees from nearly 50% of levy-paying farms. There were also numerous “phone a friend” online consultations.
Workshop topics included mushroom pathology 101, dry bubble biology and management, vectors, spot treatment training, cobweb biology and management, and on farm sampling.
Four on-farm visits allowed the team to examine vulnerabilities of different farms to pests and diseases; these visits highlighted disease hotspots and assisted farms to develop better management strategies.
A key activity of the project team has been to maintain and update the AGORA website, making it the central library of mushroom pest, disease and hygiene information. Hundreds of resources are available, including both locally produced fact sheets and articles and publications from around the world. There are also videos demonstrating sampling methods, spot treatments and pest and disease identification.
The information on AGORA provides an invaluable industry asset for understanding and managing not just pest and diseases, but the important roles of compost quality, farm hygiene and other factors.
Having such information available through AGORA has helped numerous farms manage their way through serious diseases.
Note that access to AGORA is password protected – please contact Judy Allan or Leah Bramich to obtain a login.
Information for this article has been sourced from articles and fact sheets published through the AMGA by Judy Allan and Warwick Gill, and the MU16003 final report.
This is an abridged version of the article that will appear in the magazine
Sampling Methods for Mushroom Pest and Disease Testing
This video describes how to collect samples for disease testing using molecular testing techniques.
This video was produced as part of the pest and disease management and research services (MU16003) project.
It was funded by Hort Innovation using the Mushroom Industry research and development levy and contributions from the Australian Government.
Fact sheet: Syzygites megalocarpus – Troll doll
Troll doll is caused by Syzygites megalocarpus a Zygomycete which is ubiquitous in nature, colonizing a diverse variety of dead or moribund fleshy mushrooms. Syzygites (pronounced “size‐a‐guy‐tees”) was initially observed on cultivated mushrooms between 2004 and 2007 in crops of Agaricus blazei (Sun mushroom) in Brazil.
It was first recorded in Pennsylvania in August 2011 and has since become widespread on commercial beds throughout North America.
Confined initially to late flushes of brown portobello strains of Agaricus bisporus, Syzygites has since been observed on earlier flushes and on white strains of Agaricus bisporus. Due to the mould’s tolerance to low temperatures, it has also been observed in postharvest packaged product, the mould appearing while on the store shelf.
