BLACK TRUFFLE CULTIVATION AND COMPETING FUNGI - Inra

Proceedings of the 7 th International Conference on Mushroom Biology and Mushroom Products (ICMBMP7) 2011
Conservation characteristics of initial mycorrhizal status by Tuber melanosporum or
contamination by other fungi species in truffle plantations surrounded by woodlands or
not. Examples chosen were explored in spring 2011.
Truffle plantations in wooded environments. These two explored plantations are located in
Aujols (Lot district) and Daglan (Dordogne district). They are established on shallow and stony
soils (rendosol), with mycorrhizal trees (Q. pubescens, Quercus ilex, Corylus avellana). They are
well maintained with care and producing despite relatively dry summer. Investigations on these
plantations concern the mycorrhizal status of the analyzed trees by the way of binocular loup and
microscope. At Aujols, roots samples were taken mostly on producing trees whereas in Daglan,
no producing trees were targeted.
Truffle plantation in cereals and vineyard plains landscapes. Explored plantations are located
near Angoulême (Charente district) in vast plain of cereals cultivation and wineyard region for
the Cognac production. There is neither woodland nor hedge of woods at least 300 meters from
explored plantations. They had been done on “terres de Groie” (rendosols deeper than those at
Aujols and Daglan) with mycorrhizal trees (Q. pubescens, Q. ilex, C.avellana), cultivated with
care. Irrigation was by bringing water with big tanks (3000 liters) and watering only producing
“brûlés”. Growers brought spores from crushed truffles the 3rd year of plantation on the “brûlés”
of young mycorrhizal trees which were not yet producing.
These plantations are producing better than those of the Lot and Dordogne districts. Harvest
started earlier (4 years old) and percentage of producing trees was also higher (90 to 95 %
instead of 30 to 60 %). Same type of investigations than above was done on these plantations.
RESULTS AND DISCUSSION
Results and their acquirement conditions are summarized without going into details in order to
keep this article a reasonable size.
Mycological survey in truffle environment in Lot district. It was impossible to present the
exhaustive mycological survey in the limits of this article. A synthesis was elaborated to
understand the essential.
Limestone grassland, suitable for T. melanosporum, presented common mycological
surveys. We observed that, both in grassland with Bromus erectus and Festuca ovina on edge of
woodlands and in moorland with sparse Qu. pubescens and Festuca ovina, T. melanosporum
could live with certain species (Inocybe jurana, Hebeloma edurum) but it excluded regularly the
other fungi out of its production area (located in the “brûlé”). Scleroderma verrucosum (Fig. 2)
was frequent at the limit of the T. melanosporum “brûlé” just starting or already producing. Its
presence did not seem to penalize the truffle production. Its frequent observation in this
condition means that S. verrucosum is preparing the field and helping to adapt and spread of the
truffière, transforming organic matter and structuring the soil in front of the brûlé.
Tuber brumale presence in young plantations is generally a consequence of a disturbing
technical itinerary which does not respect the fungi species dynamic and their repartition in
space and time. The ecosystem is disturbed by some cultural practices such as frequent tilling
with tractor-drawn tools. In these conditions, T. brumale, a well flexible species, occupies the
ecological niche initially planned for T. melanosporum. A bad choice of establishment
(insufficient drainage, soil with bad structure) or cultural methods unsuitable (soils compacted
with mechanic tools, fresh organic matter ploughing in soil, and excessive irrigation before
production) favours T. brumale at the expense of T. melanosporum.
Section:
Mycorrhizal mushrooms
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