Severe infection of mummy disease in the 2nd flush. It is sometimes confused with MVX.
An off-white mushrooms between white ones.
is that so-called ‘professionals’, with apparently too little experience of MVX , fail to take the problem seriously enough and work against the proposed solutions instead of with them. They use arguments such as: ‘There’s always a risk of MVX’, ‘It’s patches of mummy’, or ‘Oh, problems with the compost or spawn’ and ‘There’s no use changing the spawn’.
The most serious problems I have seen were on phase II composting yards that supplied their own farms. Infected compost and spores infected the compost during spawning.
And, as I already indicated, action is usually taken too late. The best course of action is to comple- tely empty all the growing rooms, clean and disinfect everything and start again from scratch. However, from a practical point of view and due to the size of current mushrooms farms, their sales markets and personnel , this is no longer really feasible. And unless the source of the infection is traced and identified first, the same problems will reappear a few months later. But it is no easy task eradicating infection from a farm that continues to produce mushrooms. You will have to battle with the virus on several fronts simultaneously, scan the hygiene status of the entire farm and remove the vulnerable, weak links to prevent new infections from occurring. In addition to this, it is best to use another strain of spawn that does not interact as well with the existing strain being used. This prevents older crops transferring infecti- ons as easily to newer crops. However, asking spawn producers for strains that are more incompatible with the commonly used strains delivers a blank. The answer is they are not available. Apparently, to put it politely, all the commercial strains are very closely related genetically, and interact. This therefore also transfers diseases. This form of monoculture with such a narrow genetic diversity makes our sector extremely vulnerable - and not just to viruses.
14 MUSHROOM BUSINESS
It is strange that patents have been applied for in the past for strains that do not interact.
Avoid stress factors
It appears that certain stress factors induce the virus or the mushroom mycelium to express typical MVX symptoms. There is no scientific evidence to indicate what these stress factors are; however, there are certain conditions that occur in practice that appear to act as a trigger: excessive ammonia at the spawning, excessively high temperatures during mycelium growth, anaerobic conditions for the mycelium/compost, inactive compost and evaporation problems. These stress factors can occur during many links in the chain: during spawn production, at the composting yard, during transport and on the mushroom farms.
Take responsibility! Our recent experiences with avian influenza and coronavirus have proven just how rapidly a virus can spread. Unless you are armed in advance with preventive weapons to combat disease, you will be overwhelmed and soon facing an infection of pandemic proportions. The mushroom sector is actually in a very good position. All the compost is fermented and pasteurised and fresh spawn is added each time in clean tunnels. At farm level, each new cropping cycle starts in a clean growing room, the production cycle is short and all incoming air is filtered. Compared with other sectors, it is much easier to start production clean, maintain good levels of cleanliness and avoid disease pressure building up.
That said, the entire sector must takes joint responsibility in the fight to eradicate these virus diseases. Spawn producers:
Creating virus-free spawn strains must be given the highest priority. Our knowledge of viruses lags far behind other sectors. In the 1950s and
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