BLACK TRUFFLE CULTIVATION AND COMPETING FUNGI - Inra

Proceedings of the 7 th International Conference on Mushroom Biology and Mushroom Products (ICMBMP7) 2011
trees mycorrhized with T. melanosporum and Delmas [7] analysed mostly the characteristic of
suitable soils. First truffles, which were harvested under hazel trees only 4 years after planting,
gave hope for a new rise of truffle production. French public institutions supported new truffle
plantations with grants given until 1986. When it became obvious that truffle production would
not really pick up again, all grants for planting mycorrhized trees, installing truffle irrigation and
renewing old plantations were abolished. In 1994, the 11 th National State Plan proposed that a
step of experimentation in truffle cultivation should take place before giving out new grants for
truffle plantations. In 2003, at the national truffle cultivation day organized by CTIFL in
Cuzance (Lot, France), certain regions decided to encourage again truffle plantation with new
financial aid.
Callot [8] underlined the importance of biological activity in truffle soil to explain the lack of
good results. Sourzat [9] stressed the fact that soils had not changed in one century and biologic
surrounding conditions had shifted as the farming methods had negative impacts. Fungal
successions (fungi train) of wild truffle trees with those of plantation truffle trees where the soil
was tilled were compared. In plantation, on shallow soil, no fungal succession but a disorder was
observed. This disorder means generally that competing fungi species are favoured, particularly
Tuber brumale. The principle of precaution in truffle cultivation, which was defined in “Truffe et
Trufficulture” [9], recommends a technical itinerary with 3 stages:
- Stage One: in the first two years of planting, one must be sure to achieve the best possible
success rate for the T. melanosporum infected seedling in the first two years of planting.
- Stage Two: it is important to focus on “a not too much” on the rapid growth of the mycorrhizal
trees to avoid contamination by other types of mushrooms; the modification of the environment
induced by the truffle itself (i.e. soil structure and biological activity) during the period of brûlé
formation has to be considered.
- Stage Three: once fruiting has started, the aim is to improve the quality and quantity of the
black truffle whilst ensuring a good perennial annual yield.
In 2008, the syntheses of truffle cultivation experimentations in France were published [10].
They enlighten the results provided since 1994 during the 11 th and 12 th National State Plans
State-County with the subsidies from FranceAgriMer (Oniflhor, Viniflhor) and the Regions.
These syntheses handle particularly of the truffle soils, host trees and seedling quality, technical
methods (soil managing, truffle irrigation, pruning), T. brumale contaminations. Considering
truffle soils have not really been altered for one century (in truffle traditional areas), cultural
methods today are quite well known and seedlings are correctly mycorrhized, why is it so
difficult to increase the level of the actual truffle production? The common answer is generally
that climate has become warmer and dryer. Truffle growers who are irrigating their plantations
credit regular production to this effort. Nevertheless, results are still heterogeneous. One
observes that certain non-irrigated plantations can give quite regular results whereas irrigated or
non irrigated other ones have bad results. Why?
The research programme SYSTRUF, funded by National Agency of Research (ANR),
attempts to answer this question by studying particularly the biology of the truffle. The way of
fungal competition by different species and observation of what happens in the fields are
explored by the Station of experimentation on the truffle at Cahors-Le Montat. Why is the
presence of such fungi more negative today than in the past? In other ways, why is the black
truffle less dominant than in the past, why does it defend less against its potential aggressors?
MATERIAL AND METHODS
The three types of investigations involved surveys of the fungi species in the truffle environment,
formation on the natural “truffières” on the edge of the plantation, contamination of truffle trees
Section:
Mycorrhizal mushrooms
517