Does Nature Know Best?

dwheeler at dwheeler at
Sat Jan 10 00:01:16 EST 1998

In article <LN5s00O5I8he091yn at>,
  larryc at (Larry Caldwell) wrote:
> In article <884108756.897253377 at>, dwheeler at wrote:
> > We don't know for sure, but it is probably a combination of both. For
> > example, at the first truffle farm inoculated in Oregon, the owner has
> > removed entire rows. Yet the remaining stumps continue to live. We
> > suspect the stumps (now over 2 years old) grafted roots underground with
> > nearby trees. But mycorrhizae are known to associate in complex ways,
> > forming mycorrhizal mat communities which tie in several trees and shrubs
> > together. These mat communities also stabilize otherwise unstable slopes
> > and strongly decrease erosion.
> This may not be a surprise to silviculturalists (as distinct from
> foresters).  One of the lectures in the woodland management class I
> took last fall described root grafting, and indicated it was a major
> means of transmission of laminar root rot.  The lecturer also mentioned
> that mycorrhizal species are being tested as prophylactic against root
> rot.

Dr. Trappe has already identified that T. gibbosum appears to act as a
fungal prophylactic to Douglas fir. In nature few trees associated with
Tuber gibbosum are infected with Fomes annotosum, or Douglas fir root

Since Tuber gibbosum has an obligate mycorrhizal relationship with
Douglas fir, it is essential to it's continued health to be able to deter
infection from other fungal saprophytes and parasites. But it has not
been tested to my knowledge.

> It's certainly possible.  I've read about the mycorrhizal relationship,
> and it's incredibly close.  The fungus actually interpenetrates the
> cell structure of the roots.  It's a true symbiosis, not just an
> association.
> I was an amateur mycologist long before I got involved with forestry.
> Mycorrhizal relationships are multitudinous in nature.  The entire
> genus cortinarius is mycorrhizal with fir. Unfortunately,  a good
> percentage of the species in the genus will kill you if you eat them.
> All things being equal, converting a stand of timber to edible
> mycorrhizae is a delightful prospect.

What I find fascinating is that the value of these fungi probably exceeds
the value of the tree as timber. This in turn affects all things
currently identified as forestry. A study available on the Internet
(sorry, have to search for this one, I didn't bookmark it) pointed out
that a single .5 cm length of rootlet could host 7 different species of
mycorrhizae. A mature tree has several .5 cm rootlets available. Another
source indicates that rootlets with mycorrhizae tend to survive longer
than rootlets not inoculated.

> Which brings up some questions.  I still have frozen truffle innoculant
> left over from last year.  It should be just fine, but I'm wondering if
> you have added any new species to your innoculant package in the last
> year?  If so, I may order some.  If not, I'll just stick with the batch
> from last year.

I'm sorry to say that I've forgotten what I sent you originally Larry. If
you actually have Tuber inoculant, it probably won't work without at
least one other species of mycorrhizal fungi present. Charles LaFebre, a
grad-student at OSU last July collected 20-25 roots near fruiting Tuber
giganteum. He found that all the roots were inoculated with mycorrhizae:
but _NOT_ Tuber mycorrhizae! This is the strongest data for reasoning
there is a succession of mycorrhizal fungi as trees mature that I am
aware of.

> I have another question.  You mentioned in one of your posts to
> bionet.mycology that yeast had some role in promoting the germination
> of certain fungal spores.  Is there any advantage to tossing a teaspoon
> of yeast into the innoculant slurry, or is the process more complex
> than that?

It probably wouldn't hurt, the the yeast typically is in the form of
yeast propagules. These are heat-resistant yeast "seeds" if you will,
spores that can survive very hot temperatures. Evidently these propagules
produce an exudate which is essential to some mycorrhizal spore

> My seedlings should be showing up soon.  The weather has been clement,
> which means the nursery at Elkton is able to lift seedlings on schedule.
> I'm sticking with doug fir this year, which was a bit of a miscalculation.
> It turns out that one plot may not have good enough drainage for doug
> fir, and I should have planted pine there instead.  Surprisingly, ponderosa
> pine is not only more drought tolerant than fir, it also tolerates wet
> feet better.

A hint for better seedling survival: if you can get the nursery stock
before it gets it's roots trimmed, the survival rate should be +much+
better. Since most seedlings are packaged for delivery, the roots (and
mycorrhizae) are often removed for ease of size and shipping. What is

A great many tree farmers don't know this simple fact.

> Oh well.  I still haven't come up with an innoculant package for the
> pine.  This gives me another year, unless I find some uncommitted
> seedlings.

The easiest to use is Pisolithus tinctorius. A single sporocarp produces
a good many billion spores, only a thousand or so are necessary to
inoculate a pine seedling.

Daniel B. Wheeler

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