Mycorrhizal fungi and seedling survival

Don Staples dstaples at
Wed Sep 16 09:59:44 EST 1998

dwheeler at wrote:
> Early this year I mailed some dried mycorrhizal fungi which are fairly simple
> to grow to a forest consultant nearby. Last week I looked at a new 50-acre
> plantation which had been treated with these mycorrhizal fungi. Trees were
> mostly Douglas fir, with some Grand fir, Ponderosa pine, and Lodgepole pine
> for variety. Trees were planted at about 9 foot spacings in irregular rows
> into a field that formerly was a wheat field.
> I remember telling the consulting forester that mycorrhizal fungi should
> assist in tree survival, but strongly suggested he do three different
> inoculations over a period of 6 weeks, beginning with initial planting.
> I don't think the two additional inoculations got done.
> The trees have been in the ground since about April, and were assisted by the
> wettest May Oregon has had on record.
> Nonetheless, when I saw the site last Wednesday, September 9 I was amazed at
> the lack of noticeable tree mortality. With only a limited time to look, I
> eyed about 1.5 acres, or about 3,000 trees. I found 2 fatalities, both of
> which were immediately adjacent the entrance to the field. It may even be
> that these two trees were killed by being run over by pickups, etc.
> As I recall, the mycorrhizae sent were Rhizopogon truffles. Supposedly a
> single dip-inoculation of these in a very dilute solution will colonize about
> 60 percent of the trees.
> While average tree fatality is between 5 and 15% normally, the fatality on
> this stand was considerably lower: less than 1%. I believe the Rhizopogons
> cost $25- $30, and treated 120,000-plus trees, or a cost per tree of less
> than 1 cent per 40 trees.
> Do you think it was worth it?

One anecdotal case is insufficient to make a call on, and the increased
rainfall may have a lot to do with it.  That said, if the proof is that
the treatment will reduce mortality by half on worse case scenarios, it
is worth it.  Application would be an add on to existing dips for other
purposes, so little cost other than the source of the innoculant.

Good post and thinking.
Don Staples
UIN 4653335

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