Mushroom Virus X: Diagnosis, prevention and control

It is more effective to focus on prevention of Mushroom Virus X (and other diseases) because it is more difficult to gain any control, once established. The best way to prevent or control MVX is to implement good hygiene measures. You should develop your own strategy for your specific site, based on your vulnerable areas.

The first step is to reduce the potential sources of infection, which are mushroom spores and mycelial fragments from bulk phase 3 and uncooked-out crops. Exclude these from the vulnerable processes, such as spawning, spawn-running and casing.

Phase 2 and 3 operations

• Ensure complete separation of Phase 2 spawning halls from Phase 3 emptying areas
• Ensure that spawning and Phase 3 emptying are not carried out at the same time
• Do not share machinery for handling Phase 2 and Phase 3 compost
• Ensure that Phase 3 tunnels, shelves or trays in which spawn-running is carried out are steamed before reuse

 Filtration and air pressure

• Ensure a high standard of filtration of Phase 2 and Phase 3 facilities, avoiding the ingress of unfiltered air, by installing the highest possible grade of HEPA filters
• Regularly maintain your HEPA filters and ducts
• Maintain spawning halls at positive pressure with filtered air
• Maintain Phase 3 emptying halls at neutral pressure
• Consider filtering cropping room exhausts if you’re growing open mushrooms

 Filling and casing

• Store casing under protection
• Thoroughly clean filling and casing equipment immediately before each use to avoid recontamination
• Carry out filling and casing in dust-free conditions

 Cook out

• Cook out all crops in situ at termination (65–70°C for 12 hours)

 Monitoring crops

• Monitor viral levels at regular intervals by sending samples for diagnosis