GROWING GOURMET - Anto2ni.it

Figure 124. (Jyster mushrooms out" of a
jar filled with grain spawn an event with potentially
disastrous consequences for the laboratory.
nized with mushroom mycelium. In general,
the cultivator should assume that a minor population
of contaminants will survive
"sterilization" especially as the mass of each
batch increases. Thermotolerant contaminants
are activated when temperatures within the substrate
spiral upwards.To thwart this tragedy, the
bags containing nitrogenous supplements
should be spaced well apart when placed on
open wire rack shelving. The laboratory manager
should carefully monitor air temperature
to off-set the upwardly spiralling trend of internal
temperatures.
This arena of problems is largely avoided by
using sawdust spawn for inoculation into supplemented
sawdust substrates rather than grain
spawn.Thermogenesis is reduced to a more manageable
level. Colonization is faster, more even,
and one gets more "mycelial mileage" from grain
spawn by generating intermediate sawdust spawn.
GENERATING GRAIN SPAWN 153
In essence, another exponent of expansion of the
mycelial mass has been introduced to the benefit
of overall production.
In contrast, grain spawn is preferred over
sawdust spawn for the cultivation of Oyster
mushroom on cereal straws. Grain spawn
boosts the nutritional base of straw, radically
improving yields compared to using an equal
mass of sawdust spawn.Although sawdust may
have more points of inoculation, yields are substantially
less than if the straw had been
impregnated with grain spawn. Two exceptions
are Hypsizygus ulmarius and H. tessulalus, both
of which benefit when sawdust spawn is used to
inoculate wheat straw.
In Chapter 21, the growth parameters of each
species and the recommended courses for
matching spawn and substrate for maximizing
yields and minimizing problems are described
in detail.
Spawn Storage
Spawn can be stored for only a short period
of time before a decline in viability occurs.
Those who buy spawn from afar are especially
at risk. As spawn ages, and with the depletion
of food resources, the mycelium's rate of
growth declines. Metabolic wastes accumulate.
With the loss of vitality, the mycelium's antidisease
defensive mechanisms fail. Opportunistic
molds, bacteria, viruses, and other microscopic
organisms proliferate. Good quality
spawn on Day 60 (from the date of inoculation)
can be half as viable at Day 30.
Generally, spawn should be used at peak vitality.
If it can not, only one option remains:
refrigeration. Spawn can be refrigerated for
several weeks at 35-40° F. (1. 6-4.4° C.), effectively
slowing its rate of decline, provided the
refrigeration process does not, in itself, cause
contamination to flourish. Spawn must not be
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