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124 EVALUATING A MUSHROOM STRAIN
wise accelerated through the harvest of adolescent
forms. Diseases are less likely and
consistency of production is better assured.
One general feature is common to all mushrooms
in determining the best stage for picking:
the cap margin. Cap margins reveal much about
future growth. At the youngest stages, the cap
margin is incurved, soon becoming decurved, and
eventually flattening at maturity. In my opinion,
the ideal stage for harvest is midway between
incurved and decurved. During this period, spore
release is well below peak production. Since the
gills are protected by both the curvature of the
whole mushroom as well as adorning veil remnants
(as in Shiitake), the mushrooms are not
nearly as vulnerable to damage. For more information,
please consult Chapter 23.
17. Duration from storage to spoilage:
Preservation An important aspect of evaluating
any strain is its ability to store well. Spoilage
is accelerated by bacteria which thrive under
high-moisture stagnant air conditions. A delicate
balance must be struck between
temperature, air movement, and moisture to
best prolong the storage of mushrooms.
Some species and strains are more resistant
to spoilage than others. Shiitake mushrooms
store and ship far better, on the average, than
Oyster mushrooms. Some Oyster mushrooms,
especially the slow-forming cold weather
strains, survive under cold storage longer than
the warm weather varieties. In either case,
should spores be released and germinate, bacterial
infection quickly sets in.
18. Abatement of growth subsequent to
harvest Yet another feature determining preservation
is whether or not the mushrooms stop
growing after picking. Many mushrooms continue
to enlarge, flatten out, and produce spores
long after they have been harvested. This is especially
distressing for a cultivator picking a
perfect-looking young specimen one day only
to find it transformed into a mature adult the
next day. This continued growth often places
growers and distant distributors into opposing
viewpoints concerning the quality of the
product. Strains of Pleurotuspulmonarius, especially
the so-called"Pleurotus sajor-caju" is
one such example. I like to describe this strain
of Oyster mushrooms as being "biologicallyout-of
control." (See Figure 99.)
19. Necrosis factors and the protection of
dead tissue from competitors After a mushroom
has been picked, tissue remnants become
sites for attack by predator insects and parasitic
molds. Some species, Shiitake for instance,
have a woodier stem than cap. When Shiitake
is harvested by cutting at the base of the stem,
the stem butt, still attached to the wood substrate,
browns and hardens. AS the stem butt
dies, a protective skin forms. This ability to
form a tough outer coat of cells protects not only
the left-over stem remnant from infestation, but
also prevents deep penetration by predators.
Since most Pleurotus ostreatus strains are not
graced with this defense, extreme caution must
be observed during harvest so no dead tissue
remains. The "sajor-caju" variety of Pleurotus
pulmonarius is surprising in its ability to reabsorb
dead tissue, even forming new
mushrooms on the dead body remnants of previously
harvested mushrooms.
20. Genetic stability/instability Since all
strains eventually senesce, genetic stability is
of paramount concern to every cultivator. Signs
of a strain dying are its inability to colonize a
substrate, produce primordia, or develop
healthy mushrooms.Typical warning signs are
a delay in fruiting schedules and an increasing
susceptibility to disease. These symptoms are
afew of many which suggest strain senescence.
21.Flavor Strains of the same species differ
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