The following is from NORTHWEST WOODLANDS, Fall, 1990, reprinted in
NATS Current News, Vol. 8. No. 6, Dec-Jan. 1990-91
TRUFFLING TREE FARMER
By Marshall Dunham
With the truffle market looking promising, growing truffles may be an
avenue open to tree farmers.
The most valuable mushrooms in the world are underground fungi called
"truffles," cherished by gourmet chefs as flavorings for fine foods.
The French "black diamond" truffle, Tuber melanosporum, sold for $750
a pound in 1989. The Italian white truffle, Tuber magnatum, was worth
$550 a pound in 1989. These prices reflect a large demand for a
diminishing supply of European truffles.
Thousands of species of truffles are found around the world. Most of
these are not particularly flavorful or precious, but a few are superb
culinary species with flavors capable of pleasing the most particular
palate. The Pacific Northwest is noted for an abundance of truffles,
including several membersof the genus Tuber, closely related to the
valuable European species.
Of greatest interest to Northwest tree farmers is the Oregon white
truffle, Tuber gibbosum, which prefers to grow in the roots of young
Douglas-fir trees. At maturity, the Oregon white is about the size of
a walnut and has a pleasant spicy aroma.
Truffles form a mutually beneficial relatnioship with the trees they
inhabit. The body, or mycelia, of the truffle acts as an extension of
the tree's root system, making water and nutrients available. In
return, the tree provides the truffle with sugars and other
by-products of photoshythesis. Ninety percent of all green plants have
formed similar partnerships with underground fungi, making survival
possible on marginal soils.
In the Northwest, the primary distributor of wild truffles is the
California red-back vole. The vole locates ripe truffles by their
aroma, digs them up, eats them and spreads the spores in its
Some Oregon white truffles will be found naturally on most
Douglas-fir plantations in the Pacific Northwest, depending on the
number of voles and sources of spores in the area.
Forest scientists at Oregon State University are inoculating
Douglas-fir seedlings with Tuber gibbosum spore solutions in hope of
increasing the frequency of this species on plantations. However, it
may be years before quantifiable results are available.
Meanwhile, other experimenters have tried to encourage the growth of
desirable species in established plantations. In 1986, Dan Wheeler,
one of the leading truffle collectors in the North American Truffling
Society (NATS), tried a series of spore inoculations on a tree farm
owned by Paul Bishop, a retired Portland firefighter, OSWA member and
Dan used the Oregon white truffle and six other culinary species from
his collections, making solutions which he sprayed on portions of the
Bishop property. Three years later, Dan and Paul invited the North
American Truffling Society to explore the area. The consensus of the
group was that truffles were more abundant on Bishop's tree farm than
in most of the other places they had tried that season. This was not a
rigidly controlled scientific experiment, but it does suggest it is
possible to increase the frequency of desirable species by spreading
spore solutions in suitable habitats.
One of the ways Paul Bishop encourages soil fungi on his tree farm is
by returning organic matter to the soil. "I used to have 27 burn piles
on this place, but now I don't have any," he says. "We prune the trees
and throw the branches between the rows. I drive over the slash with a
rotary mower which breaks it up pretty well. Then I run a disc over to
press the sticks into the dirt. That way it rots fast and there's no
At present, all Oregon white truffles on commercial markets are
harvested by the wild pickers who are more concerned with quantity
than quality. Many immature Tuber gibbosum which have not developed
their full aroma and flavor have been marketed, damaging the
international reputation of Oregon white truffles.
Problems with erratic quality of wild-harvested truffles may be
solved with advances in cultivation and harvesting techniques. In the
future, truffle pickers will probably use highly trained dogs to
locate and harvest only the ripe truffles in an orchard, as the
Europeans do today.
If the quality of Oregon truffles improves and the supply of European
truffles continues to decline, Oregon white truffles may eventually
command prices as high as the European species.
Dan Wheeler believes it may someday be possible for the total value
of an Oregon White truffle crop harvested yearly from a tree farm to
exceed the value of the trees grown on the same piece of land. If the
Oregon truffle industry develops as the Oregon wine business has, such
an expectation may not be unduly optimistic.
(Caution: there are some toxic fungi which bear a close resemblance
to truffles. These include deadly Amanita buttons and the pigskin
poison puffball. Mushrooms should never be eaten without positive
Marshall Dunham is a member of the Benton County Small Woodlands
Association and serves as secretary of NATS.
COMMENT BY POSTER: when this article ran, there was considerable
confusion over the concept of T. gibbosum and when it fruited.
Collections submitted to NATS had confirmed fruiting T. gibbosum from
nearly all months of the year, although production seemed to peak
twice. The largest peak was during the fall months; then 6 months
later another peak occurred. In 1989 Dr. James Trappe of OSU
considered these collections to still be the same fungus.
After questions concerning the fruiting times, appearance, size, and
other considerations was compared with the original collections of T.
gibbosum by Harkness in CA over 100 years earlier, Dr. Trappe has
since confirmed that there are two distinct flushes of T. gibbosum,
and has named them separate varieties. Tuber gibbosum var. autumnale
is the new variety and probably the most abundant form during most
years. It fruits during the farll and early winter months. Tuber
gibbosum var. gibbosum, or the original T. gibbosum, is collected both
in CA and OR during the spring months, is larger, more aromatic, and
much darker in color than T. gibbosum var. autumnale.
Both species are well known and documented at Paul Bishop's Jones
Creek Tree Farm near Oregon City.
Posted as a courtesy by
Daniel B. Wheeler