Mushroom growing
Practical Action
Bacterial blotch is the most common of diseases. It will show up as pale yellow spots
on the cap and these will darken and the cap will become slimy. Over-humid
conditions encourage bacterial blotch.
Fungal Dry Bubble or Verticillium is the most common fungal threat in Zimbabwe.
This initially shows up as brown spots on the cap and later on the mushrooms will
become deformed. Agricura’s fungicide can be used to combat the infection.
Competitor moulds will show up as unusual colours within the substrate such as
green, brown and white moulds which indicate that the growing conditions are more
suitable for these moulds than for the commercial mushrooms. There may be too
much ammonia present or the substrate may be too wet and anaerobic conditions
exist. Directly sprinkling calcitic limestone powder onto the mould will stop further
growth and in more extreme cases broad spectrum fungicides can be used.
False Truffle is resistant to pasteurisation and if these large fruitbodies appear then
the substrate should be removed and the equipment sterilised with methyl bromide.
Virus called Die Back Disease or La France Disease or Mummy Disease can
occasionally be a severe problem destroying the whole crop. An infection shows up as
absent or disappearing mycelium, deformed fruitbodies, and fruit discolouration that
may appear greyish or brownish. All the equipment should be sterilised
Harvesting
Generally mushrooms are harvested by hand using knives to cut
the ones that are ready. Pickers should be trained to recognise
the appropriate stage for harvesting and be consistent in when
the mushrooms are cropped. Handling should be kept to a
minimum to reduce the risk of damaging the crop.
The total amount harvested from a stack can be 3 to 4kg. Once
the harvest is complete the substrate is depleted and can not
support any further crops. It is usually then used as a fertiliser
for other crops.
Figure 4: Harvesting
Photo credit: Practical Action
Processing and marketing
Southern Africa.
Many mushrooms are sold fresh to retail outlets. Marketing of
fresh mushrooms presents particular problems as they should be consumed within three or
four days of harvesting to avoid spoilage. Often they are harvested in the day and sold in
wholesale markets during the early hours of the following morning, or delivered directly to
supermarkets and caterers.
Mushrooms are also suitable for drying,
enabling them to be stored for long periods
without deteriorating. This can be done using
solar drying.
In larger set-ups cold rooms can be used to
store the mushrooms before they are sent to
market. The optimum temperature for storage is
between 5 and 8°C.
Figure 5: Oyster mushrooms ready for
market. Photo credit: Practical Action Southern
Africa.
Alternatively, they can be frozen and placed in
airtight containers but unprocessed mushrooms
take up a lot of room and this can be costly way
of preserving them.
It is important to identify your market first, before investing in production. Growers should
make sure that there will be a demand for the mushrooms once they have been produced.
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