Fungi as additional tree crops

Daniel B. Wheeler dwheeler at
Sun Sep 15 23:35:48 EST 2002

In "Growing Gourmet and Medicinal Mushrooms" (c.1993, Ten Speed Press)
Paul Stamets states: "Most ecologists now recognize that a forest's
health is directly related to the presence, abundance and variety of
mycorrhizal associations."
	Dr. James M. Trappe, professor emeritus at Oregon State University,
says "It is easy to find trees in the Pacific Northwest without
mycorrhizal fungi: look for trees without green."
	Some 3,000 species of mycorrhizal fungi are known to associate with
Douglas-fir alone.
	Perhaps 50 mycorrhizal fungi have ever been cultivated. Some of these
include Geopora cooperi, Lacterius deliciosus, Genea intermedia,
Gautieria monticola, Scleroderma cepa, S. aurantiacum, S. hypogaeum;
Pisolithus tintorius, Boletus chrysenteron, B. zelleri; Laccaria
laccata, L. amethystina-occidentalis; Leucangium carthusiana; Tuber
gibbosum var. gibbosum, T. g. var. autumnale, T. gilkeyae, T.
sphaerosporum, T. spinoreticulatum, T. sp. nov.; Helvella lacunosa,
Hymenogaster parksii, Hysterangium coriaceum, Truncocolumella citrina,
Barssia oregonensis; Rhizopogon parksii, R. vinicolor, R. villescens,
R. villosulus, and R. colossus. The author has "planted" the spores of
these all species, and found fruiting bodies close to where he
"planted" them. While not definitive, it may be cultivation.
	Why are mycorrhizal fungi important to tree growers?
	Mycorrhizal fungi gather water and soil nutrients, leach phosphorus
and potassium from rock, associate with nitrogen-fixing bacteria, and
may act as fungal prophylactics against soil pathogenic fungi.
	Many mycorrhizal fungi are also expensive foods. These include the
commonplace Western chanterelle (Cantharellus formosus), the esteemed
Oregon Black truffle (Leucangium carthusiana), and the valuable
matsutake (Tricholoma magnivelare).
	Paul Stamets (op cit) notes: "Mycorrhizal mushrooms form a mutually
dependent, beneficial relationship with the roots of most plants,
ranging from trees to grasses. ... both organisms benefit from this
association. Plant growth is accelerated."
	These fungi also diversify income for tree growersand land owners. A
study in Southern Oregon with a stand of Lodgepole pine (Pinus
contorta) and matsutake (Tricholoma magnivelare) showed that the
mushroom production each year was more valuable than the trees as
	My mycorrhizal fungi inoculation methods differs from those used to
grow the French Black truffle (Tuber melanosporum) by Truffe
Agronomique of France. Rather than inoculating seedlings in nurseries,
I inoculate acres of trees at a time. My method costs a lot:
$2500/acre (about 500 trees), but compared to buying inoculated
truffle trees, costs only one-third the cost. (See costs for T.
melanosporum trees at
	Ironically, Ian Hall in "The Black Truffle" (c. 1994, New Zealand
Institute for Crop & Food Research Limited) notes that most truffle
growers still view other mycorrhizal fungi as competitors to truffle
production. The opposite may be true.
	Stamets (op cit) further states that "Fungi and their host trees may
have long associations without the appearance of edible fruitbodies."
In other words truffle mycorrhizae is not enough _by itself_ to
produce truffles.
	The North American Truffling Society (PO Box 296, Corvallis, OR
97339) has accumulated several thousand collections of truffles.  The
Oregon White truffle, Tuber gibbosum var. autumnale, is one of the
most common collections. But there are several other hypogeous fungi
which fruit at the same or different times of the year, and which are
common to Oregon White truffle producing lands. These species can be
found with younger trees. They suggest there is a successional
relationship among mycorrhizal fungi as trees age. Seedling trees (1-5
years old) have one or more of these five fungi. Oregon White truffles
are usually found among slightly older trees (5-50 year old trees).
	Matsutake (Tricholoma magnivelare) were uncommon in the Mt. St.
Helens eruption zone until after 1995, but are becoming more common.
Chanterelles (Cantharellus formosus) are found with trees as young as
15 years old in the Coast range of Oregon, but are uncommonly found
with trees less than 400 years old near Timothy Lake in the Oregon
Cascades at 3500 feet elevation. King boletes (Boletus edulis) have
been found with young Lodgepole pine near Cape Lookout, Oregon. But
may associate with only 75 year old Sitka spruce in the same area
(personal observations, author).
	While identification of mycorrhizae by root formation is still in its
infantcy, data published on the Internet has found 7 fungal species 
colonizing _the same_ .5 cm rootlet! A typical seedling tree has
hundreds of sites. A healthy, 100-year-old tree may have several
million of those sites.
	The demand for truffles and truffle products continues to rise in the
United States. Truffle producers including tree farmers may profit as
a result.
	Because truffles are also mycorrhizal, trees associated with truffles
tend to grow more rapidly. A 22-inch tall seedling tree planted at
Paul Bishop's Jones' Creek Tree Farm grew to more than 10.5 feet
between February and October, 1991. Truffles were found with the
previous tree, and with this tree at a later date.
	Helen V. Smith was an expert in Cortinarius mushroom identification,
all of which are believed to be mycorrhizal. She once found an
isolated Douglas-fir along the Oregon Coast in a sand dunes area that
was fruiting 53 species of Cortinarius _at the same time_.
	Alexander H. Smith and Nancy Smith Weber, in "The Mushroom Hunter's
Field Guide" (c. 1958, 1963, 1980 by The University of Michigan)
states in the introduction that "A single tree may (on different
roots) form mycorrhizae with several species of fungi, and there is
increasing evidence that many of the plants in a forest are
inter-connected through these mycorrhizal networks in the soil. ...
one can predict where to find a species of mushroom by studying the
distribution of its host tree. Furthermore, since trees are generally
more conspicuous than mushrooms, knowing various tree species and
their associated fungi can help collectors locate likely habitats for
particular species."
	It is possible to find many mycorrhizal fungi fruiting at different
times of the year with individual trees. Cultivation of these fungi
dramatically expands crops associated with trees. The author has found
Oregon White truffle (Tuber gibbosum var. autumnale), Oregon Gray
truffles (Tuber gibbosum var. gibbosum) and Oregon Black truffles
(Leucangium carthusiana) with the same trees at two different sites
within the same year. Sites with similar characteristics inoculated
with these truffles might reasonably produce multiple truffle crops.
	How long do truffle-inoculated trees live? No one knows at this time.
Truffles have been found with trees as young as 6 inches tall and
perhaps 3 years old. Truffles have also been found with trees 8 feet
in diameter and probably 200 (or more) years old.
	Glomalin is a protein exudate of some mycorrhizal fungi. It has been
found to sequester large quantities of CO2 for long time periods in
soils. (See
This sticky protein causes soil particles to clump together, allowing
air and water to penetrate to greater depths and increasing soil
	Dr. James M. Trappe has noted that truffle mycelium (the plant-like
portion of truffles) also produces an exudate which causes soil
particles to clump together.

The above information cannot be complete. Too few fungi have _ever_
been examined for their gastronomic importance or their association
with trees, both in forests and in plantations.  The subject in an
on-going topic of great interest to me.

Posted as a courtesy by
Daniel B. Wheeler

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