Dry bubble (Verticillium fungicola var. fungicola)
This fungus commonly occurs in the soil which may be a primary source of the infection. It may also come with casing or by transfer of infection from house to house by pickers, flies, mites or machinery. Spores can lie dormant until they come into contact with mushroom mycelium which stimulates them to grow. It causes superficial, cinnamon-brown lesions (spots) of the mushroom cap. Lesions may join into a brown blotch. A grayish bloom appears when the fungus sporulates. Infection of the stem results in a bent and/or split stipe. The second major symptom is a dry bubble - a small, puffball-like mass where the mushroom should be. Spores of this fungus spread in the air, on soil particles, splash water and on flies. Symptoms occur 10 to 14 days after infection.
- Maintain good sanitation and hygiene in the growing facilities
- Avoid soil movement near mushroom houses especially on windy days. Take measures to avoid the accumulation of dust in the vicinity of mushroom houses and also dust movement into the vicinity of mushroom houses
- Use properly prepared substrate and casing soil that have been adequately pasteusterized
- Control flies and mites and every effort should be made to prevent their entry into cropping houses.
- Pick infected bags last to minimise the risk of pickers spreading the spores
- Do not set picking trays on the ground in the production house as dust is attracted to the sides of the trays by static electricity
- Remove diseased mushrooms as they appear from the beds using a cloth or sponge soaked in disinfectant (household bleach) and then place them in a bucket containing disinfectant
- Remove spent substrate from the farm. It can be used as manure for other crops