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Burgundy Black Truffle Cultivation in an Agroforestry Practice

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AGROFORESTRY IN ACTION<br />

University of Missouri Center for <strong>Agroforestry</strong><br />

AF1015 - 2011<br />

<strong>Burgundy</strong> <strong>Black</strong> <strong>Truffle</strong> <strong>Cultivation</strong><br />

<strong>in</strong> <strong>an</strong> <strong>Agroforestry</strong> <strong>Practice</strong><br />

by Joh<strong>an</strong>n Bruhn, Ph.D., Research Associate Professor, Division<br />

of Pl<strong>an</strong>t Sciences, University of Missouri, & Michelle Hall, Senior<br />

Information Specialist, The Center for <strong>Agroforestry</strong>, University of<br />

Missouri<br />

The two best c<strong>an</strong>didate species for truffle<br />

cultivation <strong>in</strong> the south-central U.S. are the<br />

<strong>Burgundy</strong> truffle (Tuber aestivum Vitt., syn. T.<br />

unc<strong>in</strong>atum Ch., Fig. 1a) <strong>an</strong>d the Périgord black truffle<br />

(T. mel<strong>an</strong>osporum Vitt., Fig. 1b). These common names<br />

(<strong>Burgundy</strong> truffle <strong>an</strong>d Périgord black truffle) are<br />

derived from the names of two of the m<strong>an</strong>y regions<br />

<strong>in</strong> Fr<strong>an</strong>ce where they are famous. Though native<br />

to Europe, there is great <strong>in</strong>terest <strong>in</strong> exp<strong>an</strong>d<strong>in</strong>g the<br />

cultivated r<strong>an</strong>ge of both of these species.<br />

Each of these two truffle species has unique life cycle<br />

features <strong>an</strong>d characteristic habitat requirements.<br />

Although the retail price of Périgord black truffles<br />

is roughly twice that of <strong>Burgundy</strong> truffles, Périgord<br />

truffles mature dur<strong>in</strong>g the w<strong>in</strong>ter <strong>an</strong>d are destroyed<br />

if they thaw <strong>in</strong> the ground after hav<strong>in</strong>g frozen solid.<br />

In contrast, <strong>Burgundy</strong> truffles mature ma<strong>in</strong>ly <strong>in</strong> late<br />

autumn, before d<strong>an</strong>ger of the soil freez<strong>in</strong>g.<br />

In addition, the <strong>Burgundy</strong> truffle fungus c<strong>an</strong> produce<br />

higher yields per acre, perhaps because it typically<br />

grows <strong>in</strong> the shade of denser st<strong>an</strong>ds of trees. Denser<br />

st<strong>an</strong>ds of trees also serve to more effectively filter <strong>an</strong>d<br />

cle<strong>an</strong>se groundwater (for example, Allen et al. 2004).<br />

The recently discovered nitrogen fixation activities<br />

of truffles (see “The <strong>Burgundy</strong> truffle as a<br />

ectomycorhizal fungus,” below) places them <strong>in</strong><br />

the comp<strong>an</strong>y of legume nodules as agents of soil<br />

improvement (Barbieri et al. 2010).<br />

<strong>Burgundy</strong> black truffle,<br />

above. The white<br />

ve<strong>in</strong><strong>in</strong>g is composed of<br />

sterile tissue support<strong>in</strong>g<br />

the production of colorful spores. Mature spores are<br />

brown. Mycorrhizal root tips formed by the <strong>Burgundy</strong><br />

truffle are easily recognized by their ornamentation <strong>an</strong>d<br />

cell structure (left <strong>in</strong>set). Ascospores of the <strong>Burgundy</strong><br />

truffle are carmel colored with a net-like system of<br />

ridges (right <strong>in</strong>set).<br />

Table of Contents<br />

The <strong>Burgundy</strong> <strong>Truffle</strong> as a Mycorrhizal Fungus, pg. 2<br />

Why the <strong>Burgundy</strong> <strong>Truffle</strong>? pg. 4<br />

Choos<strong>in</strong>g a Tree Species, pg. 5<br />

Characteristics of a Good Pl<strong>an</strong>tation Site, pg. 6<br />

Pl<strong>an</strong>tation Site Preparation, pg. 10<br />

Pl<strong>an</strong>tation Establishment, pg. 11<br />

Pl<strong>an</strong>tation Ma<strong>in</strong>ten<strong>an</strong>ce, pg. 13<br />

Harvest<strong>in</strong>g, pg. 14<br />

Cook<strong>in</strong>g with <strong>Truffle</strong>s, pg. 16<br />

Additional Resources, pg. 17<br />

1<br />

www.centerforagroforestry.org


This stra<strong>in</strong> of Bradyrhizobium is one of<br />

m<strong>an</strong>y that we have isolated <strong>in</strong>to pure<br />

culture from with<strong>in</strong> <strong>Burgundy</strong> truffles.<br />

Bradyrhizobium species fix atmospheric<br />

nitrogen <strong>in</strong> legume nodules, but are also<br />

believed to fix nitrogen <strong>in</strong>side develop<strong>in</strong>g<br />

truffles. As a result, <strong>Burgundy</strong> truffle<br />

cultivation may improve soil quality <strong>in</strong> a<br />

m<strong>an</strong>ner similar to legume cultivation.<br />

The <strong>Burgundy</strong> truffle fungus also appears to grow<br />

<strong>an</strong>d fruit more competitively over a wider r<strong>an</strong>ge<br />

of soil conditions th<strong>an</strong> the Périgord truffle fungus.<br />

Where appropriate conditions persist, the <strong>Burgundy</strong><br />

truffle fungus appears capable of susta<strong>in</strong>ed fruit<strong>in</strong>g<br />

over centuries (Weden et al. 2004b).<br />

Signific<strong>an</strong>tly, most of what we know about the<br />

biology <strong>an</strong>d cultivation of Europe<strong>an</strong> black truffles<br />

is based on research <strong>an</strong>d experience <strong>in</strong> their native<br />

r<strong>an</strong>ges <strong>in</strong> Europe, <strong>an</strong>d much of the scientific literature<br />

concern<strong>in</strong>g the biology <strong>an</strong>d cultivation of the<br />

<strong>Burgundy</strong> truffle has been published <strong>in</strong> Europe<strong>an</strong><br />

l<strong>an</strong>guages (for example, Chevalier <strong>an</strong>d Frochet 1997,<br />

Olivier et al. 2002, Wedén 2008). Nevertheless, work<br />

<strong>in</strong> New Zeal<strong>an</strong>d (Hall et al. 2007) has demonstrated<br />

that the Périgord black truffle c<strong>an</strong> be successfully<br />

cultivated across a wider r<strong>an</strong>ge of soil conditions<br />

th<strong>an</strong> constitute its native Europe<strong>an</strong> r<strong>an</strong>ge, <strong>an</strong>d this<br />

may prove true for the <strong>Burgundy</strong> truffle as well.<br />

English l<strong>an</strong>guage reports of research <strong>in</strong>to the biology,<br />

ecology <strong>an</strong>d cultivation of the <strong>Burgundy</strong> truffle (for<br />

example, Delmas 1978; Chevalier et al. 2001; Weden<br />

et al. 2004a, 2004b <strong>an</strong>d 2009; Zambonelli et al. 2005;<br />

Hall et al 2007; Pruett et al. 2008a, 2008b, 2009; Bruhn<br />

et al. 2009; Wehrlen 2008, 2009; Wehrlen et al. 2009)<br />

have helped support research globally. In the face<br />

of limited research support, the spirit of collegiality<br />

among scientists around the world reflects the<br />

universal desire to jo<strong>in</strong>tly adv<strong>an</strong>ce these topics as<br />

quickly as possible.<br />

Despite all that is known about truffle biology<br />

<strong>an</strong>d cultivation, efforts to cultivate these exquisite<br />

mushrooms meet with variable success, often for<br />

reasons not yet understood. We might conclude that<br />

successful trufficulture today is largely based on<br />

science, with signific<strong>an</strong>t room for <strong>in</strong>spiration <strong>an</strong>d<br />

luck.<br />

For all of these reasons, the <strong>Burgundy</strong> truffle<br />

appears better suited th<strong>an</strong> the Périgord black<br />

truffle as a susta<strong>in</strong>able agroforestry specialty crop<br />

under Missouri conditions. The <strong>Burgundy</strong> truffle<br />

is probably the most widely eaten truffle species <strong>in</strong><br />

Europe (Riousset et al. 2001). The biology, ecology,<br />

cultivation <strong>an</strong>d use of the <strong>Burgundy</strong> truffle are the<br />

subjects of this publication.<br />

Before discuss<strong>in</strong>g cultivation of the <strong>Burgundy</strong><br />

truffle, we need to underst<strong>an</strong>d (to the best of<br />

current knowledge) the biology <strong>an</strong>d ecology of this<br />

remarkable fungus.<br />

<strong>Truffle</strong> cultivation is a perplex<strong>in</strong>g endeavor<br />

for several key reasons, <strong>in</strong>clud<strong>in</strong>g:<br />

1) the complex mycorrhizal nature of truffle fungi;<br />

2) the long period between truffle orchard<br />

establishment <strong>an</strong>d truffle fruit<strong>in</strong>g; <strong>an</strong>d<br />

3) the fact that <strong>Burgundy</strong> truffle “mushrooms”<br />

typically form submerged <strong>in</strong> the soil.<br />

The <strong>Burgundy</strong> <strong>Truffle</strong> as a<br />

Mycorrhizal Fungus<br />

<strong>Truffle</strong> fungi depend for their existence on the<br />

successful establishment of a mutually beneficial<br />

nutritional relationship with the root systems<br />

of receptive tree species (so-called “host” trees).<br />

This sort of mutualistic symbiosis between rootcoloniz<strong>in</strong>g<br />

truffle fungi <strong>an</strong>d receptive tree species<br />

is representative of one form of “mycorrhizal”<br />

relationship.<br />

The word mycorrhiza (plural, mycorrhizas;<br />

adjective, mycorrhizal) comes from two Greek<br />

words that tr<strong>an</strong>slate roughly as “fungus root.”<br />

In simplest terms, a truffle fungus modifies root<br />

tip <strong>an</strong>atomy of receptive pl<strong>an</strong>ts to facilitate the<br />

exch<strong>an</strong>ge of sugar produced by the pl<strong>an</strong>t (through<br />

photosynthesis) for m<strong>in</strong>erals <strong>an</strong>d water gathered by<br />

the fungus from the soil. Nearly all l<strong>an</strong>d pl<strong>an</strong>t species<br />

require some form of mycorrhizal relationship to<br />

survive (Smith <strong>an</strong>d Read 1997). Due to its f<strong>in</strong>ely<br />

br<strong>an</strong>ched structure, the fungal weft, compris<strong>in</strong>g<br />

myriad microscopic filaments, is able to forage<br />

among soil particles far more efficiently th<strong>an</strong> the f<strong>in</strong>e<br />

roots of the pl<strong>an</strong>t alone.<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

2


Most tree species associate with fungi that<br />

produce either “ectomycorrhizas” or “arbuscular<br />

mycorrhizas.” The fungi that produce ecto- vs.<br />

arbuscular mycorrhizas are quite unrelated. <strong>Truffle</strong><br />

fungi produce ectomycorrhizas. “Ecto” is the Greek<br />

prefix me<strong>an</strong><strong>in</strong>g “outside,” referr<strong>in</strong>g to the fact that<br />

ectomycorrhizal fungi affect the outward appear<strong>an</strong>ce<br />

of colonized root tips. “Arbuscular” is the Greek<br />

adjective me<strong>an</strong><strong>in</strong>g “tree-shaped,” referr<strong>in</strong>g to the<br />

tree-shaped “arbuscules” produced by the fungus<br />

with<strong>in</strong> f<strong>in</strong>e root cortex cells. Arbuscular fungi do not<br />

noticeably modify root tip appear<strong>an</strong>ce. It’s import<strong>an</strong>t<br />

to know what k<strong>in</strong>d of mycorrhizas different tree<br />

species form because arbuscular mycorrhizal fungi<br />

won’t replace <strong>an</strong> ectomycorrhizal fungus. Thus,<br />

truffle-colonized (ectomycorrhizal) oak seedl<strong>in</strong>gs<br />

c<strong>an</strong> be <strong>in</strong>terpl<strong>an</strong>ted among (arbuscular mycorrhizal)<br />

apple trees to take adv<strong>an</strong>tage of the shade provided<br />

by the apple trees. Table 1 provides lists of some<br />

common ectomycorrhizal <strong>an</strong>d arbuscular mycorrhizal<br />

tree species.<br />

Fortunately, the ectomycorrhizas produced by the<br />

<strong>Burgundy</strong> truffle fungus are quite dist<strong>in</strong>ctive <strong>an</strong>d c<strong>an</strong><br />

generally be discerned under the dissect<strong>in</strong>g <strong>an</strong>d/or<br />

compound microscope from those produced by other<br />

ectomycorrhizal fungi (Müller et al. 1996; Chevalier<br />

<strong>an</strong>d Frochot 1997). Nevertheless, nurserymen,<br />

consult<strong>an</strong>ts <strong>an</strong>d pl<strong>an</strong>tation owners alike should<br />

have the mycorrhizal condition of their greenhouse<br />

seedl<strong>in</strong>gs <strong>an</strong>d pl<strong>an</strong>tation trees evaluated by <strong>an</strong><br />

impartial laboratory. These confirmations should<br />

consist at least of a systematic microscopic evaluation.<br />

Ideally, this evaluation should be accomp<strong>an</strong>ied by<br />

extraction <strong>an</strong>d identification of fungal DNA from<br />

samples of tentatively identified truffle mycorrhizas<br />

(for example, Iotti <strong>an</strong>d Zambonelli 2006). This process<br />

is <strong>in</strong>creas<strong>in</strong>gly affordable, <strong>an</strong>d provides import<strong>an</strong>t<br />

assur<strong>an</strong>ces to all parties <strong>in</strong>volved at every stage of<br />

truffle cultivation.<br />

Systems for the <strong>in</strong>dependent certification of<br />

greenhouse seedl<strong>in</strong>g colonization are widely<br />

used <strong>in</strong> Fr<strong>an</strong>ce (Chevalier <strong>an</strong>d Grente 1978), Italy<br />

(Bencivenga et al. 1995), <strong>an</strong>d Spa<strong>in</strong> (Fischer <strong>an</strong>d<br />

Col<strong>in</strong>as 1996). Seedl<strong>in</strong>gs from greenhouse production<br />

batches that have been certified to be well colonized<br />

by the <strong>in</strong>tended truffle species are sold bear<strong>in</strong>g<br />

tags affirm<strong>in</strong>g their certification <strong>an</strong>d identify<strong>in</strong>g<br />

the certify<strong>in</strong>g agency. Systematic <strong>in</strong>dependent<br />

certification has yet to be established elsewhere.<br />

Caveat emptor… Let the buyer beware!<br />

Table 1. Some tree species known to associate with arbuscular<br />

mycorrhizal fungi <strong>an</strong>d/or ectomycorrhizal fungi.<br />

Common name Scientific Arbusc. Ecto.<br />

name<br />

Apple<br />

Ash<br />

Aspen, cottonwood,<br />

poplar*<br />

Bamboo<br />

Beech<br />

<strong>Black</strong> locust<br />

Box elder<br />

Buckeye,<br />

horse chestnut<br />

Catalpa<br />

Cherry, peach,<br />

plum*<br />

Chestnut<br />

Dogwood<br />

G<strong>in</strong>kgo<br />

Grape<br />

Hackberry<br />

Hazelnut<br />

Hickory, pec<strong>an</strong><br />

Holly<br />

Hornbeam<br />

Juniper<br />

L<strong>in</strong>den<br />

Magnolia<br />

Maple<br />

Mulberry<br />

Oak<br />

Persimmon<br />

P<strong>in</strong>e<br />

Redbud<br />

Tulip<br />

Viburnum<br />

Walnut<br />

Willow*<br />

Malus<br />

Frax<strong>in</strong>us<br />

Populus<br />

Bamusa<br />

Fagus<br />

Rob<strong>in</strong>ia<br />

Acer negundo<br />

Aesculus<br />

Catalpa<br />

Prunus<br />

Cast<strong>an</strong>ea<br />

Cornus<br />

G<strong>in</strong>kgo<br />

Vitis<br />

Celtis<br />

Corylus<br />

Carya<br />

Ilex<br />

Carp<strong>in</strong>us<br />

Juniperus<br />

Tilia<br />

Magnolia<br />

Acer<br />

Morus<br />

Quercus<br />

Diospyros<br />

P<strong>in</strong>us<br />

Cercis<br />

Liriodendron<br />

Viburnum<br />

Jugl<strong>an</strong>s<br />

Salix<br />

A<br />

A<br />

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3<br />

www.centerforagroforestry.org


An Agritruffe oak<br />

seedl<strong>in</strong>g certified by<br />

the French INRA to<br />

be colonized by the<br />

<strong>Burgundy</strong> truffle.<br />

(Inset) Examples of<br />

French <strong>an</strong>d Sp<strong>an</strong>ish<br />

tags used to label<br />

seedl<strong>in</strong>gs certified to<br />

be colonized by truffle<br />

fungi.<br />

To make th<strong>in</strong>gs more “<strong>in</strong>terest<strong>in</strong>g,” it is clear now<br />

that mycorrhizal fungi (truffle fungi <strong>in</strong>cluded)<br />

associate with a wide variety of bacteria that<br />

<strong>in</strong>fluence mycorrhiza formation <strong>an</strong>d function (for<br />

example, Frey-Klett et al. 2007, Bonf<strong>an</strong>te <strong>an</strong>d Anca<br />

2009). Quite recently, it has been shown that truffle<br />

fruit bodies also host large <strong>an</strong>d diverse bacterial<br />

communities (Barbieri et al. 2005, 2007), that <strong>in</strong>clude<br />

nitrogen-fix<strong>in</strong>g bacteria (Cerig<strong>in</strong>i et al. 2008, Barbieri<br />

et al. 2010) closely related to those that nodulate the<br />

root systems of legumes. The roles of bacteria present<br />

<strong>in</strong> large numbers <strong>in</strong> <strong>Burgundy</strong> truffle mycorrhizas<br />

<strong>an</strong>d fruit-bodies are the subject of ongo<strong>in</strong>g research<br />

(Bruhn, Emerich, Wedén, <strong>an</strong>d Backlund, <strong>in</strong><br />

preparation).<br />

The <strong>in</strong>troduction of selected bacterial stra<strong>in</strong>s <strong>in</strong>to<br />

truffle seedl<strong>in</strong>g production systems is <strong>an</strong> excit<strong>in</strong>g<br />

prospect (for example, Thrall et al. 2005). One of<br />

the difficulties <strong>in</strong> resolv<strong>in</strong>g the requirements for<br />

truffle cultivation is the potential disconnect between<br />

the successful establishment of a mycorrhizal root<br />

system <strong>an</strong>d its subsequent production of truffle<br />

mushrooms. In other words, a successful mycorrhizal<br />

relationship is essential to successful fruit<strong>in</strong>g but<br />

may not guar<strong>an</strong>tee it. It rema<strong>in</strong>s to be determ<strong>in</strong>ed<br />

how similar are the bacterial communities associated<br />

with mycorrhiza formation <strong>an</strong>d function, <strong>an</strong>d truffle<br />

mushroom <strong>in</strong>itiation <strong>an</strong>d development.<br />

<strong>Truffle</strong> life cycles comprise two<br />

<strong>in</strong>dependent phases:<br />

1) The nutritional relationship between the truffle<br />

fungus, its partner tree, <strong>an</strong>d associated microbes; <strong>an</strong>d<br />

2) The sexual reproduction of the fungus <strong>in</strong> the form<br />

of truffle mushrooms.<br />

This issue is difficult to study because <strong>Burgundy</strong><br />

truffle production commonly lags pl<strong>an</strong>t<strong>in</strong>g of<br />

mycorrhizal tree seedl<strong>in</strong>gs by six to 10 years<br />

(Chevalier et al. 2001, Wedén et al. 2009). Full<br />

production may be reached by orchard age 12-15<br />

years, <strong>an</strong>d is commonly associated with the<br />

establishment of shade <strong>an</strong>d a litter layer.<br />

F<strong>in</strong>ally, when (<strong>an</strong>d if) <strong>Burgundy</strong> truffles do develop<br />

<strong>in</strong> a pl<strong>an</strong>tation, they generally form completely below<br />

the soil surface. As a result, effective harvest <strong>an</strong>d<br />

evaluation of production requires the services of a<br />

well-tra<strong>in</strong>ed dog to f<strong>in</strong>d them as they mature.<br />

So, to summarize, if you do everyth<strong>in</strong>g right<br />

(<strong>in</strong>tentionally <strong>an</strong>d with some good luck), your truffle<br />

orchard will eventually yield tens of pounds of<br />

truffles per acre for years, but if you make <strong>an</strong>y error<br />

you won’t even know it for 10 years, but you will<br />

have a very pleas<strong>an</strong>t st<strong>an</strong>d of lovely trees ! This guide<br />

is designed to provide a general knowledge of truffle<br />

biology <strong>an</strong>d the state-of-the-art of <strong>Burgundy</strong> truffle<br />

cultivation. We have taken care to draw attention to<br />

the limits of our underst<strong>an</strong>d<strong>in</strong>g, so that the potential<br />

trufficulteur (truffle grower) c<strong>an</strong> bal<strong>an</strong>ce the potential<br />

for success with the risks of failure, based on current<br />

knowledge <strong>an</strong>d its apparent gaps.<br />

Why the <strong>Burgundy</strong> <strong>Truffle</strong>?<br />

The success of a truffle cultivation effort depends on<br />

the match<strong>in</strong>g of a truffle species with a receptive tree<br />

species on a mutually conducive site. Although the<br />

<strong>Burgundy</strong> <strong>an</strong>d Périgord black truffle species share<br />

common features, they differ markedly <strong>in</strong> a number<br />

of import<strong>an</strong>t ways that <strong>in</strong>fluence their productivity<br />

under m<strong>an</strong>agement.<br />

First, the <strong>Burgundy</strong> truffle matures ma<strong>in</strong>ly from<br />

September through J<strong>an</strong>uary <strong>in</strong> <strong>Burgundy</strong>, Fr<strong>an</strong>ce,<br />

<strong>an</strong>d from late August through early December on<br />

Gotl<strong>an</strong>d, Sweden (Chevalier <strong>an</strong>d Frochot 1997, Wedén<br />

et al. 2004b). In contrast, the Périgord truffle fruits<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

4


dur<strong>in</strong>g the w<strong>in</strong>ter, matur<strong>in</strong>g between early December<br />

<strong>an</strong>d mid-March <strong>in</strong> Europe (Olivier et al. 2002). This<br />

difference is supremely import<strong>an</strong>t, because when<br />

truffles freeze <strong>in</strong> the ground, they rot upon thaw<strong>in</strong>g<br />

<strong>an</strong>d are unmarketable (Riousset et al. 2001, Chevalier<br />

<strong>an</strong>d Frochot 1997). Thus, the Périgord black truffle<br />

is poorly suited to locations where the soil rout<strong>in</strong>ely<br />

freezes solid for more th<strong>an</strong> a couple of days at a time<br />

dur<strong>in</strong>g w<strong>in</strong>ter. For this reason, we recommend the<br />

<strong>Burgundy</strong> truffle for cultivation throughout Missouri.<br />

Second, <strong>in</strong> locations where the soil does not<br />

characteristically freeze dur<strong>in</strong>g the w<strong>in</strong>ter, the choice<br />

of Périgord or <strong>Burgundy</strong> truffle is more a matter<br />

of economics <strong>an</strong>d preference. With its stronger<br />

fragr<strong>an</strong>ce <strong>an</strong>d flavor, top-quality Périgord black<br />

truffles have sold <strong>in</strong> recent years for approximately<br />

$900/lb. <strong>in</strong> the U.S., roughly twice the price of<br />

the <strong>Burgundy</strong> truffle. Both species of truffle are<br />

approximately twice as expensive <strong>in</strong> the U.S. as <strong>in</strong><br />

Europe, due to their greater availability <strong>in</strong> Europe.<br />

Most Périgord black <strong>an</strong>d <strong>Burgundy</strong> truffles currently<br />

sold <strong>in</strong> the U.S. are imported from Europe, with some<br />

very notable exceptions (http://www.tennesseetruffle.<br />

com/). Price also varies subst<strong>an</strong>tially with <strong>in</strong>dividual<br />

truffle size <strong>an</strong>d quality. In these early times, both<br />

Périgord black <strong>an</strong>d <strong>Burgundy</strong> truffles are <strong>in</strong> great<br />

dem<strong>an</strong>d at exclusive restaur<strong>an</strong>ts engag<strong>in</strong>g <strong>in</strong><br />

haute cuis<strong>in</strong>e. Knowledgeable Missouri<strong>an</strong>s appear<br />

more will<strong>in</strong>g to experiment with the purchase of a<br />

<strong>Burgundy</strong> truffle, due to the price differential.<br />

Third, yields of the <strong>Burgundy</strong> truffle c<strong>an</strong> be greater<br />

th<strong>an</strong> those of the Périgord truffle, <strong>in</strong> part due to<br />

the greater pl<strong>an</strong>t<strong>in</strong>g density recommended for<br />

<strong>Burgundy</strong> truffle orchards (see “Pl<strong>an</strong>t Density”,<br />

under “Orchard Establishment”, below). Further,<br />

the <strong>Burgundy</strong> truffle fungus is generally considered<br />

to be more aggressive th<strong>an</strong> the Périgord truffle <strong>in</strong><br />

compet<strong>in</strong>g with coexist<strong>in</strong>g native mycorrhizal fungi,<br />

so pl<strong>an</strong>tations established with the <strong>Burgundy</strong> truffle<br />

c<strong>an</strong> have a longer productive life. F<strong>in</strong>ally, the greater<br />

tree density <strong>in</strong> <strong>Burgundy</strong> truffle orchards creates a<br />

much more forested environment, which may be seen<br />

as a value <strong>in</strong> itself, improv<strong>in</strong>g groundwater filtration,<br />

wildlife habitat, <strong>an</strong>d nitrogen fixation associated with<br />

the truffle fungus.<br />

Choos<strong>in</strong>g a Tree Species<br />

The <strong>Burgundy</strong> truffle fungus is capable of associat<strong>in</strong>g<br />

with a wide r<strong>an</strong>ge of tree species, but experience<br />

shows that truffle production is greater <strong>in</strong> partnership<br />

Table 2. A list of tree species known to associate with the <strong>Burgundy</strong><br />

truffle (Chevalier et al. 2001).<br />

Tree species<br />

Carp<strong>in</strong>us betulus<br />

Cedrus atl<strong>an</strong>tica<br />

Corylus avell<strong>an</strong>a<br />

C. colurna<br />

Ostrya carp<strong>in</strong>ifolia<br />

Q. petraea<br />

Q. pubescens<br />

Q. robur<br />

P<strong>in</strong>us nigra ssp. austriaca<br />

Common name<br />

Europe<strong>an</strong> hornbeam<br />

cedar<br />

common hazelnut<br />

Turkish hazelnut<br />

hop hornbeam<br />

sessile oak<br />

pubescent oak<br />

common oak<br />

Austri<strong>an</strong> black p<strong>in</strong>e<br />

with some tree species th<strong>an</strong> with others. Table 2<br />

presents a list of tree species known to associate<br />

well with the <strong>Burgundy</strong> truffle (Chevalier et al.<br />

2001). First, <strong>an</strong> appropriate tree species needs to be<br />

receptive to f<strong>in</strong>e-root colonization by the <strong>Burgundy</strong><br />

truffle fungus both <strong>in</strong> the greenhouse <strong>an</strong>d at the<br />

pl<strong>an</strong>tation site. So, it also seems import<strong>an</strong>t to use a<br />

tree species that is preferentially colonized by the<br />

<strong>Burgundy</strong> truffle fungus after outpl<strong>an</strong>t<strong>in</strong>g <strong>in</strong> the field.<br />

For example, the <strong>Burgundy</strong> truffle is very productive<br />

with the Europe<strong>an</strong> hazelnut (Corylus avell<strong>an</strong>a L.),<br />

yet C. avell<strong>an</strong>a seems to be quite receptive to a wide<br />

variety of compet<strong>in</strong>g ectomycorrhizal fungi as well.<br />

It is also import<strong>an</strong>t to select a tree species that will<br />

grow well under exist<strong>in</strong>g climate <strong>an</strong>d soil conditions<br />

at the pl<strong>an</strong>tation site. For example, the common oak<br />

(Quercus robur L.) is one of the pr<strong>in</strong>cipal tree species<br />

(along with C. avell<strong>an</strong>a) associated with the <strong>Burgundy</strong><br />

truffle on Gotl<strong>an</strong>d. Yet seed sources (proven<strong>an</strong>ces)<br />

of Q. robur vary <strong>in</strong> their cold hard<strong>in</strong>ess <strong>an</strong>d <strong>in</strong> their<br />

toler<strong>an</strong>ce of the high soil pH levels required (above<br />

7.0). These environmental sensitivities need to be<br />

considered when select<strong>in</strong>g seed sources.<br />

It’s tempt<strong>in</strong>g to w<strong>an</strong>t to select a proven tree species<br />

from the native r<strong>an</strong>ge of the <strong>Burgundy</strong> truffle, but<br />

native North Americ<strong>an</strong> tree species should not<br />

be automatically ruled out. For example, native<br />

tree species resist<strong>an</strong>t to local diseases <strong>an</strong>d pests<br />

may prove to be good <strong>Burgundy</strong> truffle associates<br />

compared to related native Europe<strong>an</strong> species.<br />

Examples of diseases which require consideration<br />

<strong>in</strong> the U.S. <strong>in</strong>clude: northern filbert blight (caused<br />

by the fungus Anisogramma <strong>an</strong>omala), which c<strong>an</strong> be<br />

especially severe on Europe<strong>an</strong> hazelnut; chestnut<br />

5<br />

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light (caused by the fungus Endothia parasitica)<br />

on oaks <strong>an</strong>d ch<strong>in</strong>quap<strong>in</strong>; <strong>an</strong>d powdery mildew of<br />

common oak (caused by several fungi, <strong>in</strong>clud<strong>in</strong>g<br />

Microsphaera alphitoides). For example, we have found<br />

that the hybrid Q. robur x Q. bicolor Willd. is resist<strong>an</strong>t<br />

to powdery mildew, while rema<strong>in</strong><strong>in</strong>g receptive to the<br />

<strong>Burgundy</strong> truffle.<br />

A Quercus robur seedl<strong>in</strong>g display<strong>in</strong>g a high level of powdery<br />

mildew on its foliage. Wire mesh is commonly used<br />

to protect young seedl<strong>in</strong>gs from rabbit damage.<br />

With these <strong>in</strong>sights, we c<strong>an</strong> proceed to consider<br />

the characteristics of a favorable <strong>Burgundy</strong> truffle<br />

orchard site, site preparation, the establishment <strong>an</strong>d<br />

m<strong>an</strong>agement of the truffière, <strong>an</strong>d the eventual harvest<br />

<strong>an</strong>d utilization of the truffles produced!<br />

Characteristics of a Good<br />

<strong>Burgundy</strong> <strong>Truffle</strong> Pl<strong>an</strong>tation Site<br />

The suitability of a site for <strong>Burgundy</strong> truffle<br />

cultivation depends on several <strong>in</strong>ter-related <strong>an</strong>d<br />

equally import<strong>an</strong>t categories of factors: climate <strong>an</strong>d<br />

position <strong>in</strong> the l<strong>an</strong>dscape; l<strong>an</strong>d-use history; soil<br />

properties; <strong>an</strong>d access to water.<br />

Climate <strong>an</strong>d Position <strong>in</strong> the L<strong>an</strong>dscape<br />

Analyses of climatic conditions conducive to<br />

<strong>Burgundy</strong> truffle fruit<strong>in</strong>g have naturally focused on<br />

relationships between truffle harvests <strong>an</strong>d <strong>an</strong>nual<br />

patterns of air temperature <strong>an</strong>d precipitation with<strong>in</strong><br />

the <strong>Burgundy</strong> truffle’s native Europe<strong>an</strong> geographic<br />

r<strong>an</strong>ge (Table 3). Precipitation dur<strong>in</strong>g the period<br />

June through September, as well as total <strong>an</strong>nual<br />

precipitation, seems to be well correlated with <strong>an</strong>nual<br />

<strong>Burgundy</strong> truffle harvests <strong>in</strong> Fr<strong>an</strong>ce (Chevalier <strong>an</strong>d<br />

Table 3. Me<strong>an</strong> precipitation <strong>an</strong>d temperature for Cruzy, <strong>Burgundy</strong>, <strong>in</strong> Fr<strong>an</strong>ce, <strong>an</strong>d on the Swedish isl<strong>an</strong>d of Gotl<strong>an</strong>d (Wedén et al.,<br />

2004b). Data for Missouri represent <strong>an</strong> orchard pl<strong>an</strong>t<strong>in</strong>g with established <strong>Burgundy</strong> truffle mycorrhizae.<br />

Monthly me<strong>an</strong><br />

precipitation (mm)<br />

Monthly me<strong>an</strong><br />

temperature (C)<br />

Ma<strong>in</strong> season for f<strong>in</strong>d<strong>in</strong>g mature<br />

Tuber aestivum a fruit<strong>in</strong>g<br />

bodies (exceptions exist)<br />

Month Gotl<strong>an</strong>d <strong>Burgundy</strong> Missouri Gotl<strong>an</strong>d <strong>Burgundy</strong> Missouri Gotl<strong>an</strong>d <strong>Burgundy</strong><br />

J<strong>an</strong>uary<br />

February<br />

March<br />

April<br />

May<br />

June<br />

July<br />

August<br />

September<br />

October<br />

November<br />

December<br />

43.3<br />

32.6<br />

34.6<br />

29.3<br />

28.0<br />

39.5<br />

51.6<br />

48.5<br />

56.8<br />

50.5<br />

57.5<br />

55.5<br />

73.6<br />

69.3<br />

69.3<br />

60.4<br />

81.9<br />

75.9<br />

65.4<br />

66.4<br />

72.0<br />

80.0<br />

83.2<br />

87.1<br />

65.4<br />

54.0<br />

58.0<br />

75.1<br />

131.6<br />

136.7<br />

98.8<br />

108.6<br />

60.9<br />

69.4<br />

56.2<br />

32.0<br />

-1.1<br />

-1.8<br />

0.1<br />

4.0<br />

9.6<br />

14.3<br />

16.3<br />

15.9<br />

12.1<br />

8.1<br />

3.9<br />

0.7<br />

2.7<br />

3.6<br />

6.5<br />

9.0<br />

13.2<br />

16.0<br />

18.7<br />

18.6<br />

15.1<br />

10.9<br />

5.9<br />

3.8<br />

-0.2<br />

0.9<br />

7.7<br />

14.5<br />

18.7<br />

23.2<br />

26.3<br />

25.8<br />

20.0<br />

13.4<br />

7.3<br />

1.2<br />

///////<br />

//////////////<br />

//////////////<br />

//////////////<br />

///////////////<br />

///////<br />

//////////////<br />

//////////////<br />

//////////////<br />

a<br />

French values are recalculated from m.e./100 g to %<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

6


Frochot 1997, Chevalier et al. 2001). Chevalier et al.<br />

(2001) estimate optimal monthly grow<strong>in</strong>g season<br />

precipitation <strong>in</strong> Fr<strong>an</strong>ce to be: April, 20-50 mm (0.8-2<br />

<strong>in</strong>); May, 60-80 mm (2.4-3.1 <strong>in</strong>); June, 60-80 mm (2.4-<br />

3.1 <strong>in</strong>); July, 50-100 mm (2-3.9 <strong>in</strong>); August, 60-80 mm<br />

(2.4-3.1 <strong>in</strong>); <strong>an</strong>d September, 40-60 mm (1.6-2.4 <strong>in</strong>).<br />

In fact, greater precipitation dur<strong>in</strong>g June through<br />

September seems to favor fruit<strong>in</strong>g. As a case <strong>in</strong><br />

po<strong>in</strong>t, heavy precipitation <strong>in</strong> July 2010 resulted <strong>in</strong><br />

strong late-season fruit<strong>in</strong>g <strong>in</strong> the Lorra<strong>in</strong>e (personal<br />

communication, Dr. Christophe Rob<strong>in</strong> <strong>an</strong>d Mr.<br />

Je<strong>an</strong>-Sébasti<strong>an</strong> Pousse). No comparable relationship<br />

to productivity is yet available for Gotl<strong>an</strong>d, where<br />

average May, June <strong>an</strong>d August precipitation is lower<br />

th<strong>an</strong> <strong>in</strong> <strong>Burgundy</strong>. Average precipitation April<br />

through September <strong>in</strong> central Missouri is greater th<strong>an</strong><br />

averages reported for <strong>Burgundy</strong> <strong>an</strong>d Gotl<strong>an</strong>d.<br />

The relationship between monthly air temperature<br />

<strong>an</strong>d truffle harvest is not yet clear. Slightly lower<br />

average monthly temperatures on Gotl<strong>an</strong>d (Wedén<br />

et al. 2004b) result <strong>in</strong> earlier onset <strong>an</strong>d conclusion<br />

of <strong>Burgundy</strong> truffle fruit<strong>in</strong>g there th<strong>an</strong> <strong>in</strong> Fr<strong>an</strong>ce. In<br />

Missouri, April-October temperatures are warmer<br />

th<strong>an</strong> <strong>in</strong> Europe, but the cool<strong>in</strong>g effect of greater<br />

precipitation may mitigate the effect of higher air<br />

temperature. We c<strong>an</strong> only speculate.<br />

M<strong>an</strong>ipulation of tree spac<strong>in</strong>g <strong>an</strong>d density permits the<br />

<strong>Burgundy</strong> truffle to be cultivated on modest slopes of<br />

almost <strong>an</strong>y aspect (for example, Chevalier et al. 2001).<br />

For example, on gentle south-fac<strong>in</strong>g slopes, the shade<br />

provided by a greater tree density <strong>an</strong>d/or closer<br />

spac<strong>in</strong>g <strong>in</strong> east-west rows c<strong>an</strong> mitigate the dry<strong>in</strong>g<br />

effects of warmer temperature <strong>an</strong>d greater exposure<br />

to the sun.<br />

The <strong>Burgundy</strong> truffle fungus does not tolerate poorly<br />

dra<strong>in</strong>ed soils (“wet feet”), so flood pla<strong>in</strong>s are very<br />

<strong>in</strong>appropriate sites for trufficulture.<br />

Slope positions below wooded areas may conta<strong>in</strong><br />

especially high <strong>in</strong>oculum levels (“spore b<strong>an</strong>ks”)<br />

of competitor ectomycorrhizal fungi, s<strong>in</strong>ce both<br />

overl<strong>an</strong>d <strong>an</strong>d groundwater dra<strong>in</strong>age of uphill<br />

wooded areas would certa<strong>in</strong>ly carry spores <strong>in</strong>to<br />

the l<strong>an</strong>dscape below. The two other ma<strong>in</strong> factors<br />

contribut<strong>in</strong>g to spore b<strong>an</strong>ks of ectomycorrhizal<br />

fungi on potential truffle pl<strong>an</strong>tation sites are: 1) the<br />

extension of ectomycorrhizal tree roots for 50-meters<br />

or more <strong>in</strong>to adjacent open areas; <strong>an</strong>d 2) the fecal<br />

deposits of <strong>an</strong>imals (for example, deer <strong>an</strong>d burrow<strong>in</strong>g<br />

rodents) that feed on various ectomycorrhizal<br />

mushrooms (for example, Ashk<strong>an</strong>nejhad <strong>an</strong>d Horton<br />

2006).<br />

L<strong>an</strong>d-use History<br />

It has been strongly <strong>an</strong>d justifiably recommended<br />

that truffle orchards be established on l<strong>an</strong>d that has<br />

not been occupied by ectomycorrhizal tree species<br />

for m<strong>an</strong>y years. Soils associated with previous<br />

ectomycorrhizal forest vegetation are pre-<strong>in</strong>fested<br />

with native ectomycorrhizal fungi well adapted to<br />

the site <strong>an</strong>d likely to compete effectively with the<br />

truffle fungus. Because the roots of trees extend <strong>in</strong>to<br />

open areas well beyond the extent of their c<strong>an</strong>opies,<br />

it has also been recommended that truffle orchards<br />

be surrounded by a 50-meter buffer of previously<br />

unforested l<strong>an</strong>d.<br />

Throughout the south-central U.S., a great deal of<br />

forested l<strong>an</strong>d was cleared dur<strong>in</strong>g the early 20th<br />

century <strong>an</strong>d converted at least temporarily to<br />

agriculture. Soil quality <strong>an</strong>d site productivity varied<br />

dramatically. Poorer sites were either ab<strong>an</strong>doned<br />

or grazed, <strong>an</strong>d better sites were often fertilized <strong>an</strong>d<br />

cropped. In contrast to conventional agriculture,<br />

truffle cultivation is most often successful on poor<br />

quality soils that have not been rout<strong>in</strong>ely fertilized.<br />

The <strong>in</strong>tensity of root colonization by truffle fungi is<br />

<strong>in</strong>versely related to soil fertility; seedl<strong>in</strong>gs <strong>in</strong> fertile<br />

soils are capable of resist<strong>in</strong>g <strong>in</strong>fection by mycorrhizal<br />

fungi.<br />

The presence of legumes may be a source of nitrogenfix<strong>in</strong>g<br />

bacteria for truffle development, but it rema<strong>in</strong>s<br />

to be determ<strong>in</strong>ed whether the same stra<strong>in</strong>s of bacteria<br />

that fix atmospheric nitrogen efficiently <strong>in</strong> legume<br />

nodules are also effective <strong>in</strong> association with the<br />

<strong>Burgundy</strong> truffle fungus. The specificity of bacterial<br />

stra<strong>in</strong>s with different legumes is well known (Thrall<br />

et al. 2005), so truffle fungi also may perform best<br />

with their own uniquely adapted bacterial stra<strong>in</strong>s.<br />

Greenhouse trials with bacterial stra<strong>in</strong>s isolated from<br />

the <strong>Burgundy</strong> truffle fungus need to be conducted.<br />

Soil Properties<br />

Much of what we know about appropriate soils<br />

for effective <strong>Burgundy</strong> truffle cultivation is based<br />

on studies conducted with<strong>in</strong> the native (Europe<strong>an</strong>)<br />

r<strong>an</strong>ges of this truffle species. Yet we also know that<br />

some truffle species have been very successfully<br />

cultivated on rather different soils outside of Europe.<br />

Experience <strong>in</strong> New Zeal<strong>an</strong>d has demonstrated that<br />

7<br />

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Table 4. R<strong>an</strong>ges of soil characteristics for productive <strong>Burgundy</strong> truffle sites <strong>in</strong> Fr<strong>an</strong>ce (Chevalier <strong>an</strong>d Frochot, 1997), <strong>an</strong>d on the Swedish<br />

isl<strong>an</strong>d of Gotl<strong>an</strong>d (Wedén et al., 2004b). Data for Missouri represent <strong>an</strong> orchard pl<strong>an</strong>t<strong>in</strong>g with established <strong>Burgundy</strong> truffle mycorrhizae.<br />

Sweden<br />

Fr<strong>an</strong>ce<br />

Missouri<br />

Measured parameter Me<strong>an</strong> R<strong>an</strong>ge Me<strong>an</strong> R<strong>an</strong>ge R<strong>an</strong>ge<br />

Clay


formation (<strong>an</strong>d thus truffle production). This is why<br />

well-fertilized agricultural soils are not recommended<br />

as truffle pl<strong>an</strong>tation sites. Still, the <strong>Burgundy</strong> truffle<br />

fungus is deemed more toler<strong>an</strong>t th<strong>an</strong> the Périgord<br />

black truffle of relatively high phosphorus <strong>an</strong>d/or<br />

potassium levels (Chevalier et al. 2001).<br />

In addition to the clear requirement for high pH<br />

associated with high soil levels of Ca <strong>an</strong>d Mg, the<br />

<strong>Burgundy</strong> truffle thrives <strong>in</strong> soils with 9-12% org<strong>an</strong>ic<br />

matter, even as high as 20% (Chevalier et al. 2001,<br />

Wedén et al. 2004b). Fortunately, soil pH <strong>an</strong>d org<strong>an</strong>ic<br />

matter level c<strong>an</strong> be m<strong>an</strong>ipulated relatively easily <strong>an</strong>d<br />

<strong>in</strong>expensively with amendments of crushed limestone<br />

<strong>an</strong>d various forms of org<strong>an</strong>ic matter. Appropriate<br />

ratios of Ca:Mg <strong>an</strong>d K:Mg c<strong>an</strong> be approximately<br />

obta<strong>in</strong>ed by judicious selection of agricultural<br />

crushed dolomitic lime sources from with<strong>in</strong> the<br />

region.<br />

Technically, a soil’s pH value is its relative acidity,<br />

def<strong>in</strong>ed as the negative logarithm of the hydrogen ion<br />

concentration. A pH value of 7.0 is neutral (neither<br />

acidic nor alkal<strong>in</strong>e). Soils with pH values below<br />

7.0 are <strong>in</strong>creas<strong>in</strong>gly acidic (higher concentrations<br />

of hydrogen ions), whereas pH values greater th<strong>an</strong><br />

7.0 <strong>in</strong>dicate <strong>in</strong>creas<strong>in</strong>g alkal<strong>in</strong>ity (lower hydrogen<br />

ion concentrations as a result of higher calcium,<br />

magnesium <strong>an</strong>d potassium ion concentrations).<br />

Unlike most agronomic crops, the <strong>Burgundy</strong> truffle<br />

fungus clearly requires a soil pH above 7.0 for<br />

fruit<strong>in</strong>g (Riousset et al. 2001).<br />

Nutrient-hold<strong>in</strong>g capacity is directly related to a<br />

soil’s clay <strong>an</strong>d org<strong>an</strong>ic matter content. The <strong>Burgundy</strong><br />

truffle thrives with moderate levels of clay <strong>an</strong>d<br />

org<strong>an</strong>ic matter (Chevalier et al. 2001, Wedén et al.<br />

2004b), as long as the soil is well-aerated <strong>an</strong>d freely<br />

dra<strong>in</strong><strong>in</strong>g (Riousset et al. 2001). Soil dra<strong>in</strong>age c<strong>an</strong><br />

become restricted at high levels of clay content, but<br />

clay particles tend to aggregate at the high pH levels<br />

favored by the <strong>Burgundy</strong> truffle, improv<strong>in</strong>g soil<br />

aeration <strong>an</strong>d dra<strong>in</strong>age.<br />

Figure 1 highlights the r<strong>an</strong>ge of soil textures<br />

associated with productive truffle pl<strong>an</strong>tations known<br />

from Fr<strong>an</strong>ce, Italy <strong>an</strong>d Gotl<strong>an</strong>d (Chevalier et al. 2001).<br />

Despite signific<strong>an</strong>t overlaps the r<strong>an</strong>ges of soil texture<br />

associated with <strong>Burgundy</strong> truffle habitat differ<br />

subst<strong>an</strong>tially among these three regions. Will data<br />

from new regions extend the r<strong>an</strong>ge of soil textures<br />

known to support <strong>Burgundy</strong> truffle production? The<br />

red l<strong>in</strong>es demonstrate how to p<strong>in</strong>po<strong>in</strong>t the soil texture<br />

of a typical Missouri silt loam soil.<br />

Access to Water – Irrigation<br />

F<strong>in</strong>ally, pl<strong>an</strong>tation sites with access to water for<br />

seasonal irrigation have a dist<strong>in</strong>ct adv<strong>an</strong>tage over<br />

sites where irrigation is not feasible. We have already<br />

mentioned the relationship between grow<strong>in</strong>g season<br />

precipitation <strong>an</strong>d truffle harvest (see “Climate <strong>an</strong>d<br />

L<strong>an</strong>dscape Position,” above), <strong>an</strong>d the south-central<br />

U.S. often experiences a dry mid-summer period. It<br />

is widely believed that the <strong>Burgundy</strong> truffle fungus<br />

forms truffle mushroom primordia dur<strong>in</strong>g the<br />

spr<strong>in</strong>g <strong>an</strong>d summer. Unlike most other mushrooms,<br />

<strong>Burgundy</strong> truffles apparently develop slowly over a<br />

period of months before matur<strong>in</strong>g to their full size<br />

<strong>an</strong>d fragr<strong>an</strong>ce. Thus, for maximum productivity,<br />

growers should be prepared to supplement natural<br />

precipitation with overhead irrigation every two<br />

weeks from late spr<strong>in</strong>g through early autumn to<br />

ma<strong>in</strong>ta<strong>in</strong> optimum levels of precipitation. (See<br />

“Irrigation,” under “Orchard Site Preparation,”<br />

below.)<br />

Top: Spr<strong>in</strong>g-form rakes are widely used<br />

for <strong>in</strong>corporation of lime <strong>an</strong>d other<br />

amendments <strong>in</strong> truffle site preparation<br />

<strong>an</strong>d ma<strong>in</strong>ten<strong>an</strong>ce. The disadv<strong>an</strong>tage<br />

to this tool is that it drags roots through<br />

the soil, which c<strong>an</strong> spread unw<strong>an</strong>ted<br />

compet<strong>in</strong>g mycorrhizal fungi around<br />

the pl<strong>an</strong>tation. Middle <strong>an</strong>d bottom: Two<br />

implements useful <strong>in</strong> establish<strong>in</strong>g <strong>an</strong>d<br />

ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g <strong>Burgundy</strong> truffle pl<strong>an</strong>tations<br />

<strong>in</strong> the Lorra<strong>in</strong>e, Fr<strong>an</strong>ce. Middle:<br />

The comb at the top of the blade is<br />

used to clear heavy grass or brush,<br />

<strong>an</strong>d the blade is used to aerate the soil<br />

to 2-ft. depth <strong>in</strong> prepar<strong>in</strong>g the pl<strong>an</strong>t<strong>in</strong>g<br />

bed. A key feature of the tool is the two<br />

side w<strong>in</strong>gs that loosen the soil laterally<br />

<strong>in</strong> addition to the vertical slic<strong>in</strong>g<br />

accomplished by the blade. One result<br />

is that no air pockets are left <strong>in</strong> the soil.<br />

Bottom: This device is used <strong>in</strong> the very<br />

early spr<strong>in</strong>g to regenerate f<strong>in</strong>e roots <strong>in</strong><br />

the pl<strong>an</strong>tation. The 8-<strong>in</strong>. teeth accomplish<br />

both aeration <strong>an</strong>d disturb<strong>an</strong>ce of<br />

lateral roots. New f<strong>in</strong>e roots grow <strong>in</strong>to<br />

the disturbed upper soil as quickly as<br />

two months after treatment. In contrast<br />

to the spr<strong>in</strong>g-form rake, this tool is not<br />

dragged across the pl<strong>an</strong>tation; <strong>in</strong>stead<br />

it is repeatedly moved <strong>an</strong>d rocked to<br />

accomplish slic<strong>in</strong>g without dragg<strong>in</strong>g.<br />

9<br />

www.centerforagroforestry.org


Pl<strong>an</strong>tation Site Preparation<br />

Once <strong>an</strong> appropriate orchard site has been selected,<br />

the first steps <strong>in</strong> truffle cultivation are to make <strong>an</strong>y<br />

desirable soil modifications <strong>an</strong>d to <strong>in</strong>stall other useful<br />

<strong>in</strong>frastructure.<br />

Soil Amendment<br />

The most critical soil modification is the adjustment<br />

of soil pH by the addition of lime to the upper 30 cm<br />

(12 <strong>in</strong>) of soil. Rais<strong>in</strong>g the pH <strong>in</strong>to the appropriate<br />

r<strong>an</strong>ge may however affect the availability of other<br />

import<strong>an</strong>t pl<strong>an</strong>t nutrients (for example, iron,<br />

magnesium, phosphorus <strong>an</strong>d trace elements). For<br />

this reason, there are nutritional adv<strong>an</strong>tages to us<strong>in</strong>g<br />

crushed dolomitic limestone, especially “reddish”<br />

forms that conta<strong>in</strong> subst<strong>an</strong>tial qu<strong>an</strong>tities of iron as<br />

well as magnesium. Generally, amendment of levels<br />

of iron, phosphorus <strong>an</strong>d trace nutrients (if necessary)<br />

may be best made after pl<strong>an</strong>tation establishment,<br />

based on <strong>an</strong>alysis of foliar nutrient content, if nutrient<br />

deficiency is evident (Hall et al. 2007).<br />

A rule of thumb suggests that approximately 1-1.5<br />

tons per hectare of f<strong>in</strong>ely crushed limestone are<br />

required to raise the pH of a soil by 0.1 pH unit for<br />

each 10 cm of soil depth be<strong>in</strong>g treated (Hall et al.,<br />

2007). Additional chip-sized limestone (0.5-1 ton per<br />

hectare) c<strong>an</strong> be added to provide buffer<strong>in</strong>g <strong>in</strong>to the<br />

future. Because it may take up to a year for soil pH to<br />

equilibrate after lim<strong>in</strong>g, it may be necessary to apply<br />

lime more th<strong>an</strong> once <strong>in</strong> prepar<strong>in</strong>g the pl<strong>an</strong>tation site,<br />

<strong>an</strong>d because the lime needs to be thoroughly mixed<br />

<strong>in</strong>to the soil, trees should not be pl<strong>an</strong>ted until <strong>an</strong><br />

acceptable pH level (at least 7.5) has been achieved.<br />

The most appropriate form of lime is generally a<br />

crushed dolomitic limestone, conta<strong>in</strong><strong>in</strong>g subst<strong>an</strong>tial<br />

levels of magnesium (<strong>an</strong>d ideally iron) as well as<br />

calcium, because the calcium/magnesium bal<strong>an</strong>ce<br />

is import<strong>an</strong>t to pl<strong>an</strong>t nutrition, <strong>an</strong>d because iron<br />

becomes less available to pl<strong>an</strong>ts as the pH <strong>in</strong>creases.<br />

If sufficient iron is not naturally available (based on<br />

appear<strong>an</strong>ce of characteristic symptoms of stunted<br />

growth <strong>an</strong>d yellow<strong>in</strong>g foliage), it c<strong>an</strong> be applied as a<br />

supplemental foliar spray.<br />

Lim<strong>in</strong>g materials are available <strong>in</strong> several forms,<br />

which vary <strong>in</strong> their nutritional content <strong>an</strong>d rate of<br />

<strong>in</strong>corporation <strong>in</strong>to the soil. Agricultural or pelletized<br />

lime (pel lime) <strong>in</strong>corporates <strong>in</strong>to the soil more<br />

rapidly th<strong>an</strong> dolomitic lime but does not contribute<br />

signific<strong>an</strong>tly to levels of iron, magnesium or other<br />

m<strong>in</strong>erals. Depend<strong>in</strong>g on various factors, it may take<br />

a year for soil pH to equilibrate after <strong>in</strong>corporation<br />

of a dolomitic lime treatment <strong>in</strong>to the upper 1-ft<br />

(30-cm) of soil. Because currently available models<br />

of pH response to lime treatments are unreliable at<br />

pH values above 7.0, it’s best to modify orchard site<br />

soil pH <strong>in</strong> stages so as not to raise soil pH above 8.0.<br />

Thus, one should pl<strong>an</strong> for orchard soil preparation<br />

to take at least two years. There are m<strong>an</strong>y different<br />

k<strong>in</strong>ds of implements that c<strong>an</strong> be used to <strong>in</strong>corporate<br />

soil amendments. The objective is to <strong>in</strong>corporate<br />

amendments as uniformly as possible without<br />

destroy<strong>in</strong>g soil structure. Too m<strong>an</strong>y passes over a site<br />

c<strong>an</strong> “polish” the <strong>in</strong>terface between the amended soil<br />

<strong>an</strong>d the subsoil, result<strong>in</strong>g <strong>in</strong> poor dra<strong>in</strong>age. Because<br />

each lime application needs to be <strong>in</strong>corporated fairly<br />

uniformly <strong>in</strong>to the soil, amendment needs to be<br />

completed before <strong>in</strong>fected trees are pl<strong>an</strong>ted on the<br />

site to avoid damag<strong>in</strong>g develop<strong>in</strong>g root systems. The<br />

spr<strong>in</strong>g-form rake depicted <strong>in</strong> Figure X is commonly<br />

used to <strong>in</strong>corporate supplemental lime <strong>in</strong>to pl<strong>an</strong>tation<br />

soil.<br />

Weed M<strong>an</strong>agement<br />

Exist<strong>in</strong>g vegetation on orchard sites competes with<br />

truffle seedl<strong>in</strong>g root systems for space, water <strong>an</strong>d<br />

nutrients. On the other h<strong>an</strong>d, short-lived pl<strong>an</strong>t<br />

roots contribute org<strong>an</strong>ic matter while loosen<strong>in</strong>g<br />

soil structure, <strong>an</strong>d legumes contribute valuable<br />

nitrogen to the soil. Other pl<strong>an</strong>ts may contribute to<br />

development of a <strong>Burgundy</strong> truffle ecosystem <strong>in</strong><br />

ways still unknown.<br />

Nevertheless, too much weedy vegetation c<strong>an</strong><br />

acidify the soil as org<strong>an</strong>ic matter decomposes<br />

to produce weak acids. Thus it is common<br />

practice to reduce compet<strong>in</strong>g vegetation prior to<br />

pl<strong>an</strong>tation establishment. Vegetation control c<strong>an</strong> be<br />

accomplished us<strong>in</strong>g mulch<strong>in</strong>g materials, herbicides,<br />

graz<strong>in</strong>g <strong>an</strong>imals or by very close mow<strong>in</strong>g. The<br />

herbicides Roundup® (glyphosate) <strong>an</strong>d Buster®<br />

(glufos<strong>in</strong>ate-ammonium) seem to be well tolerated<br />

by the <strong>Burgundy</strong> truffle fungus (Chevalier et al. 2001)<br />

though care must be taken not to let these herbicides<br />

drift onto tree foliage! The effects of m<strong>an</strong>y different<br />

mulch<strong>in</strong>g materials <strong>an</strong>d fabrics are yet unclear but it<br />

has been demonstrated that the <strong>Burgundy</strong> truffle c<strong>an</strong><br />

benefit from vegetation control us<strong>in</strong>g black, waterpermeable<br />

mulch<strong>in</strong>g fabric (Zambonelli et al. 2005).<br />

Mow<strong>in</strong>g has the tw<strong>in</strong> disadv<strong>an</strong>tages of be<strong>in</strong>g time<br />

consum<strong>in</strong>g while also contribut<strong>in</strong>g to soil compaction<br />

over time.<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

10


Weedy tree species on <strong>an</strong> orchard site need to be<br />

treated accord<strong>in</strong>g to their mycorrhizal character (EM<br />

or AM). Because the tree species most commonly<br />

associated with the <strong>Burgundy</strong> truffle (hazels <strong>an</strong>d<br />

oaks) are EM, the presence of AM trees does not<br />

pose a threat of mycorrhizal fungus competition to<br />

the truffle fungus, <strong>an</strong>d the AM trees may contribute<br />

useful shade. If direct competition between AM <strong>an</strong>d<br />

truffle trees is considered problematic, the AM trees<br />

c<strong>an</strong> simply be removed from the site. On the other<br />

h<strong>an</strong>d, EM trees <strong>in</strong> the vic<strong>in</strong>ity of <strong>an</strong> orchard should<br />

be treated differently. When possible, orchards<br />

should be located at some dist<strong>an</strong>ce from natural EM<br />

woodl<strong>an</strong>ds to reduce competition between native<br />

EM fungi <strong>an</strong>d the cultivated truffle fungus. If native<br />

EM trees occur on <strong>an</strong> orchard site, it’s preferable to<br />

cut them off <strong>an</strong>d poison the stump rather th<strong>an</strong> try<strong>in</strong>g<br />

to remove the stump <strong>an</strong>d root system from the soil.<br />

Invariably, efforts to remove root systems leave<br />

mycorrhizal f<strong>in</strong>e roots <strong>in</strong> the soil <strong>an</strong>d have the effect<br />

of spread<strong>in</strong>g EM fungi with<strong>in</strong> the orchard site. Table<br />

4 presents a list of tree genera commonly associated<br />

with AM or EM fungi.<br />

Irrigation<br />

<strong>Truffle</strong> orchard development <strong>an</strong>d fruit<strong>in</strong>g both<br />

benefit from adequate soil moisture year-round.<br />

While truffle fungi do not like “wet feet,” develop<strong>in</strong>g<br />

truffles are damaged dur<strong>in</strong>g prolonged dry periods.<br />

The mid-summer period is particularly critical <strong>in</strong><br />

the truffle life cycle because young truffles become<br />

<strong>in</strong>dependent of their orig<strong>in</strong>at<strong>in</strong>g root system <strong>an</strong>d are<br />

especially vulnerable to desiccation.<br />

Overhead irrigation is much superior to drip<br />

irrigation because:<br />

1) It provides moisture to truffles wherever they may<br />

be develop<strong>in</strong>g;<br />

2) It favors the development of a wider-spread<strong>in</strong>g<br />

root system.<br />

Fenc<strong>in</strong>g<br />

Perhaps the f<strong>in</strong>al element of orchard site preparation<br />

is the fenc<strong>in</strong>g of the area for exclusion of unw<strong>an</strong>ted<br />

<strong>an</strong>imals (both two- <strong>an</strong>d four-legged species). Fences<br />

are generally warr<strong>an</strong>ted where trespass by deer,<br />

livestock, feral hogs or people are a concern. Fences<br />

for exclusion of deer are commonly 10 ft. tall,<br />

constructed of heavy wire with a closer mesh at the<br />

bottom for exclusion of smaller <strong>an</strong>imals (goats, sheep,<br />

rabbits). Feral hogs c<strong>an</strong> be discouraged from digg<strong>in</strong>g<br />

under the fence by extend<strong>in</strong>g it approximately 2 ft.<br />

below ground, curv<strong>in</strong>g outward from the orchard<br />

up to 3 ft. There may be some added adv<strong>an</strong>tage to<br />

<strong>in</strong>stall<strong>in</strong>g str<strong>an</strong>ds of solar-powered electrified wire<br />

1-3 ft. above ground, 1 ft. outside the fence. The<br />

illustration below presents a fence of this type.<br />

Deer- <strong>an</strong>d<br />

hog-proof<br />

fence surround<strong>in</strong>g<br />

the<br />

<strong>Burgundy</strong><br />

truffle truffière<br />

site at the Maison de la Truffe museum <strong>in</strong> Boncourt-sur-Meuse,<br />

the Lorra<strong>in</strong>e, Fr<strong>an</strong>ce. A unique<br />

feature is that the fence extends 0.5 meters below<br />

the soil surface, curv<strong>in</strong>g outward away from<br />

the truffière for about 1 meter. The below-ground<br />

extension of the fence prevents all but the most<br />

determ<strong>in</strong>ed <strong>an</strong>imals (badgers, for example, see<br />

<strong>in</strong>set photo) from burrow<strong>in</strong>g <strong>in</strong>to the truffière.<br />

Missouri climates commonly feature a dry summer<br />

period. It is advisable to provide the equivalent of a<br />

summer shower to prevent dry periods of more th<strong>an</strong><br />

two weeks’ duration. (See ”Climate <strong>an</strong>d L<strong>an</strong>dscape<br />

Position” under “Characteristics of a Good <strong>Burgundy</strong><br />

<strong>Truffle</strong> Pl<strong>an</strong>tation Site,” above.) Both precipitation<br />

<strong>an</strong>d irrigation have the additional benefit of<br />

moderat<strong>in</strong>g high summer soil temperatures.<br />

Pl<strong>an</strong>tation Establishment<br />

One major difference between the preferred habitats<br />

of the <strong>Burgundy</strong> vs. Périgord truffles <strong>in</strong>volves<br />

openness of the orchard floor. Périgord truffle<br />

development is favored by full access of sunlight<br />

to the orchard floor, whereas fruit<strong>in</strong>g by the<br />

<strong>Burgundy</strong> truffle is favored by subst<strong>an</strong>tial shade<br />

<strong>an</strong>d development of a litter layer. In fact, it is widely<br />

11<br />

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elieved that the <strong>Burgundy</strong> truffle fruits poorly<br />

if at all until c<strong>an</strong>opy closure occurs. As a result,<br />

there is a longer <strong>in</strong>terval between pl<strong>an</strong>t<strong>in</strong>g <strong>an</strong>d<br />

harvest of <strong>Burgundy</strong> truffles th<strong>an</strong> is the case with<br />

Périgord truffles (approximately eight vs. five years,<br />

respectively).<br />

Pl<strong>an</strong>t Density<br />

The pl<strong>an</strong>t<strong>in</strong>g design <strong>an</strong>d tree density <strong>in</strong> a truffle<br />

pl<strong>an</strong>tation needs to take <strong>in</strong>to consideration the<br />

species of truffle be<strong>in</strong>g cultivated, the tree species<br />

selected, <strong>an</strong>d site characteristics. Further, pl<strong>an</strong>tation<br />

tree density <strong>an</strong>d tree species composition may need<br />

to be adjusted as the pl<strong>an</strong>tation matures.<br />

Because the <strong>Burgundy</strong> truffle benefits from shade<br />

<strong>an</strong>d a litter layer, tree densities will generally<br />

be much higher <strong>in</strong> <strong>Burgundy</strong> truffle pl<strong>an</strong>tations<br />

(perhaps 400-1200 trees/ha) th<strong>an</strong> <strong>in</strong> pl<strong>an</strong>tations of<br />

the Périgord truffle which thrives with full access of<br />

sun to the soil (400 trees/ha or fewer) (Chevalier et<br />

al. 2001). Tree density c<strong>an</strong> be reduced as trees grow<br />

<strong>an</strong>d beg<strong>in</strong> to cast shade. Perhaps the most obvious<br />

approach would be to pl<strong>an</strong>t <strong>in</strong>fected seedl<strong>in</strong>gs<br />

more densely, but <strong>in</strong>fected seedl<strong>in</strong>gs are quite<br />

expensive <strong>an</strong>d would eventually need to be th<strong>in</strong>ned.<br />

An alternative approach would be to <strong>in</strong>terpl<strong>an</strong>t<br />

truffle <strong>in</strong>oculated trees among previously-pl<strong>an</strong>ted<br />

arbuscular mycorrhizal “shelter trees” (see Table<br />

1), whose sole purpose is to provide early shade to<br />

hasten the onset of fruit<strong>in</strong>g (Wehrlen et al. 2009).<br />

A very productive,<br />

centuriesold<br />

hazel grove<br />

on Gotl<strong>an</strong>d. Note<br />

the closed c<strong>an</strong>opy<br />

that seems to<br />

be a requirement<br />

for abund<strong>an</strong>t<br />

<strong>Burgundy</strong> truffle<br />

fruit<strong>in</strong>g.<br />

A typical <strong>Burgundy</strong> truffle pl<strong>an</strong>tation<br />

(mostly Europe<strong>an</strong> hazel,<br />

<strong>in</strong>set), located <strong>in</strong> Boncourt-sur-<br />

Meuse (the Lorra<strong>in</strong>e, Fr<strong>an</strong>ce).<br />

Because hazels are generally smaller <strong>an</strong>d shorterlived<br />

th<strong>an</strong> oaks, yet beg<strong>in</strong> to produce truffles at <strong>an</strong><br />

earlier age th<strong>an</strong> oaks, it is possible to alternate oaks<br />

<strong>an</strong>d hazels with<strong>in</strong> pl<strong>an</strong>tation rows with the <strong>in</strong>tention<br />

of gradually remov<strong>in</strong>g hazels as the pl<strong>an</strong>tation<br />

matures (Hall et al. 2007).<br />

Tree densities <strong>in</strong> <strong>Burgundy</strong> truffle pl<strong>an</strong>tations should<br />

be lower under conditions favor<strong>in</strong>g rapid tree growth<br />

<strong>an</strong>d/or larger tree stature (Chevalier et al. 2001), such<br />

as fertile <strong>an</strong>d/or deep soils, access to irrigation, <strong>an</strong>d<br />

<strong>in</strong> pl<strong>an</strong>tations of tree species which atta<strong>in</strong> greater<br />

stature at maturity (oaks compared to hazels, for<br />

example). Pl<strong>an</strong>tation density c<strong>an</strong> also be lower on<br />

north-fac<strong>in</strong>g slopes th<strong>an</strong> on other aspects (due to<br />

greater natural shade).<br />

Comp<strong>an</strong>ion Pl<strong>an</strong>t<strong>in</strong>gs<br />

Weeds have been loosely def<strong>in</strong>ed as pl<strong>an</strong>ts that are<br />

grow<strong>in</strong>g where you don’t w<strong>an</strong>t them. However,<br />

a number of woody <strong>an</strong>d herbaceous pl<strong>an</strong>t species<br />

are suspected of contribut<strong>in</strong>g to truffle habitat <strong>an</strong>d<br />

nutrition.<br />

It has recently been shown that a variety of bacteria<br />

related to those that fix nitrogen <strong>in</strong> legume nodules<br />

occur <strong>in</strong> large numbers with<strong>in</strong> truffle fruit bodies.<br />

In our ongo<strong>in</strong>g studies of bacterial communities<br />

with<strong>in</strong> <strong>Burgundy</strong> truffle fruit bodies, we have<br />

recently isolated <strong>in</strong>to pure culture nitrogen-fix<strong>in</strong>g<br />

bacteria closely related to stra<strong>in</strong>s of Bradyrhizobium<br />

<strong>an</strong>d S<strong>in</strong>orhizobium melilloti commonly used<br />

<strong>in</strong> agriculture. Itali<strong>an</strong> colleagues have now<br />

demonstrated nitrogen fixation with<strong>in</strong> fruit bodies<br />

of T. borchii Vitt. (<strong>an</strong>other truffle species) by the<br />

acetylene reduction technique (Barbieri et al. 2010).<br />

This raises the question of whether or not the nitrogen<br />

produced by these bacteria is essential to mycorrhizae<br />

formation <strong>an</strong>d/or fruit<strong>in</strong>g of truffle fungi. If the<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

12


<strong>an</strong>swer is “yes,” then modest populations of nitrogenfix<strong>in</strong>g<br />

hosts might ensure the well-distributed<br />

presence of these bacteria across a truffle orchard site.<br />

It may also prove adv<strong>an</strong>tageous to simult<strong>an</strong>eously<br />

<strong>in</strong>oculate seedl<strong>in</strong>gs <strong>in</strong> the greenhouse with selected<br />

bacterial stra<strong>in</strong>s as well as the desired truffle fungus.<br />

Pl<strong>an</strong>t<strong>in</strong>g<br />

There are m<strong>an</strong>y ways to “put a tree <strong>in</strong> the ground”!<br />

But <strong>in</strong> establish<strong>in</strong>g a truffle pl<strong>an</strong>tation, we are<br />

pl<strong>an</strong>t<strong>in</strong>g precious tree seedl<strong>in</strong>gs pa<strong>in</strong>stak<strong>in</strong>gly<br />

produced to be well-colonized by the <strong>Burgundy</strong><br />

truffle fungus <strong>in</strong>to ground that has been carefully<br />

prepared to support truffle development. Wouldn’t<br />

it be a shame to pl<strong>an</strong>t these expensive trees <strong>in</strong> <strong>an</strong>y<br />

sub-optimum m<strong>an</strong>ner? So what do we know about<br />

properly pl<strong>an</strong>t<strong>in</strong>g truffle seedl<strong>in</strong>gs?<br />

We c<strong>an</strong> learn from a technique that is currently<br />

f<strong>in</strong>d<strong>in</strong>g favor <strong>in</strong> Fr<strong>an</strong>ce. In this technique, developed<br />

jo<strong>in</strong>tly by the French INRA <strong>an</strong>d equipment<br />

m<strong>an</strong>ufacturer Claude Becker (Toul, Fr<strong>an</strong>ce), pl<strong>an</strong>t<strong>in</strong>g<br />

beds 1 meter wide are prepared along the slope<br />

contour us<strong>in</strong>g Becker’s “culti-sous-soleur” tool (see<br />

center image, pg. 9). The comb above the blade is<br />

first used to rake away larger herbaceous vegetation<br />

<strong>an</strong>d brush. The w<strong>in</strong>ged blade is then used to loosen<br />

the soil to a depth of 0.6 meter without overturn<strong>in</strong>g<br />

the soil horizons. Three strokes are made with the<br />

blade; the first stroke def<strong>in</strong>es the center of the row.<br />

The second <strong>an</strong>d third strokes are made parallel to the<br />

first, 0.5 meters to each side with the blade <strong>an</strong>gled to<br />

br<strong>in</strong>g soil toward the center, form<strong>in</strong>g a raised bed 0.2-<br />

0.4 meters high. An import<strong>an</strong>t feature of this method<br />

is that strokes are discont<strong>in</strong>uous along the pl<strong>an</strong>t<strong>in</strong>g<br />

bed, result<strong>in</strong>g <strong>in</strong> m<strong>in</strong>imal dragg<strong>in</strong>g of debris (roots,<br />

etc.) across the site. A skilled operator c<strong>an</strong> produce<br />

100 meters of pl<strong>an</strong>t<strong>in</strong>g bed, 1 meter wide, per hour.<br />

While this tool will not be available everywhere, <strong>an</strong>y<br />

pl<strong>an</strong>t<strong>in</strong>g bed preparation technique that emulates this<br />

effect would be helpful.<br />

Once the raised pl<strong>an</strong>t<strong>in</strong>g bed has been formed, it is<br />

import<strong>an</strong>t to pl<strong>an</strong>t seedl<strong>in</strong>gs at the appropriate depth.<br />

Oaks <strong>an</strong>d hazels should be pl<strong>an</strong>ted with the soil level<br />

approximately at the po<strong>in</strong>t of attachment of the acorn<br />

or nut.<br />

Rabbits <strong>an</strong>d mice c<strong>an</strong> cause serious damage to young<br />

seedl<strong>in</strong>gs by eat<strong>in</strong>g twigs <strong>an</strong>d/or girdl<strong>in</strong>g seedl<strong>in</strong>gs<br />

(eat<strong>in</strong>g the tender bark). In areas where rodents<br />

abound, seedl<strong>in</strong>gs need to be protected by mesh or<br />

solid tubes (for example, Wedén et al. 2009).<br />

Pl<strong>an</strong>tation Ma<strong>in</strong>ten<strong>an</strong>ce<br />

Due to the broader habitat toler<strong>an</strong>ce of the <strong>Burgundy</strong><br />

truffle, pl<strong>an</strong>tation ma<strong>in</strong>ten<strong>an</strong>ce is somewhat less<br />

<strong>in</strong>volved for the <strong>Burgundy</strong> truffle th<strong>an</strong> for the<br />

Périgord truffle, but the follow<strong>in</strong>g concerns are very<br />

real.<br />

M<strong>an</strong>ag<strong>in</strong>g Compaction<br />

Because the <strong>Burgundy</strong> truffle prefers well-aerated<br />

soils, it is import<strong>an</strong>t to m<strong>in</strong>imize soil compaction<br />

<strong>in</strong> the process of establish<strong>in</strong>g <strong>an</strong>d ma<strong>in</strong>ta<strong>in</strong><strong>in</strong>g the<br />

truffle orchard. This c<strong>an</strong> be accomplished: 1) by us<strong>in</strong>g<br />

lightweight equipment <strong>in</strong> pl<strong>an</strong>tation m<strong>an</strong>agement;<br />

2) by us<strong>in</strong>g equipment with balloon tires for broader<br />

weight distribution; <strong>an</strong>d 3) by m<strong>in</strong>imiz<strong>in</strong>g the<br />

number of equipment passes over time through the<br />

pl<strong>an</strong>tation.<br />

Soil <strong>Cultivation</strong> <strong>an</strong>d Supplemental Lim<strong>in</strong>g<br />

Soil cultivation is used to <strong>in</strong>corporate lime or other<br />

supplemental fertilizer, <strong>an</strong>d to loosen soil structure<br />

to facilitate truffle growth <strong>an</strong>d size. However,<br />

cultivation should only be practiced spar<strong>in</strong>gly to<br />

avoid compaction, <strong>an</strong>d <strong>in</strong> a m<strong>an</strong>ner that avoids<br />

dragg<strong>in</strong>g roots contam<strong>in</strong>ated by compet<strong>in</strong>g<br />

ectomycorrhizal fungi throughout the pl<strong>an</strong>tation<br />

(Chevalier et al. 2001). When necessary, cultivation<br />

should be accomplished <strong>in</strong> the early spr<strong>in</strong>g, as soon<br />

as the soil is dry enough to m<strong>in</strong>imize compaction,<br />

yet prior to the <strong>in</strong>itiation of new mycorrhizas (<strong>in</strong><br />

other words, as early as late February or March, if<br />

possible).<br />

The “pioche herse,” developed by Claude Becker of<br />

Toul, Fr<strong>an</strong>ce (see bottom photo, page 9), cultivates the<br />

soil to a depth of 20 cm (8 <strong>in</strong>) by repeatedly pick<strong>in</strong>g<br />

up, sett<strong>in</strong>g down, <strong>an</strong>d rock<strong>in</strong>g the plate with six teeth<br />

<strong>in</strong> the soil while avoid<strong>in</strong>g <strong>an</strong>y dragg<strong>in</strong>g affect. Others<br />

have used roto-tiller-like equipment with blades<br />

bent vertical to sever roots to 10-cm depth <strong>in</strong> order<br />

to refresh truffle mycorrhizas, loosen the soil <strong>an</strong>d<br />

improve productivity.<br />

One persistent concern that may be addressed by<br />

soil cultivation (Chevalier <strong>an</strong>d Frochot 1997) is the<br />

deleterious effect of <strong>Burgundy</strong> truffle <strong>in</strong>itiation too<br />

close to the soil surface. <strong>Truffle</strong>s that form too close<br />

to the soil surface may be more easily damaged<br />

by <strong>in</strong>sects <strong>an</strong>d/or desiccation. Loosen<strong>in</strong>g the soil<br />

13<br />

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to 10 or 20 cm may encourage deeper root<strong>in</strong>g <strong>an</strong>d<br />

consequently deeper fruit<strong>in</strong>g by the truffle fungus.<br />

On pl<strong>an</strong>tation sites where it was necessary to<br />

add lime to raise the soil pH dur<strong>in</strong>g <strong>in</strong>itial site<br />

preparation, several factors result <strong>in</strong> gradual soil<br />

acidification. These factors <strong>in</strong>clude the gradual<br />

leach<strong>in</strong>g of calcium <strong>an</strong>d magnesium, <strong>an</strong>d the<br />

decomposition of org<strong>an</strong>ic matter to form org<strong>an</strong>ic<br />

acids. Without the buffer<strong>in</strong>g effect of naturally<br />

occurr<strong>in</strong>g limestone, it will eventually become<br />

necessary to add additional agricultural lime<br />

(perhaps once per decade) to ma<strong>in</strong>ta<strong>in</strong> the soil<br />

pH at 7.5 or greater. This c<strong>an</strong> be accomplished <strong>in</strong><br />

conjunction with early spr<strong>in</strong>g soil cultivation.<br />

Water M<strong>an</strong>agement<br />

It is useful to th<strong>in</strong>k of the life of a truffle pl<strong>an</strong>tation<br />

as compris<strong>in</strong>g two phases: <strong>an</strong> establishment (prefruit<strong>in</strong>g)<br />

period; <strong>an</strong>d a mature, productive period.<br />

Irrigation dur<strong>in</strong>g the pre-fruit<strong>in</strong>g period is designed<br />

to support development of a well-colonized root<br />

system throughout the orchard, whereas irrigation<br />

dur<strong>in</strong>g the productive period is more concerned with<br />

the survival <strong>an</strong>d growth of the truffle fruit bodies.<br />

Because truffle fruit bodies develop over a period of<br />

months, <strong>an</strong>d develop<strong>in</strong>g truffles are quite susceptible<br />

to desiccation, adequate soil moisture needs to<br />

be ma<strong>in</strong>ta<strong>in</strong>ed throughout the grow<strong>in</strong>g season<br />

(Chevalier et al. 2001, Riousset et al., 2001). In the<br />

south-central U.S., it will be import<strong>an</strong>t to supplement<br />

natural precipitation dur<strong>in</strong>g<br />

periods of summer drought. A<br />

useful rule of thumb is to irrigate<br />

every two weeks <strong>in</strong> the absence of<br />

natural ra<strong>in</strong>fall, target<strong>in</strong>g optimum<br />

monthly summer precipitation<br />

values. (See “Climate <strong>an</strong>d Position<br />

<strong>in</strong> the L<strong>an</strong>dscape,” pg. 6). Keep<br />

<strong>in</strong> m<strong>in</strong>d, however, that excessive<br />

irrigation is worse th<strong>an</strong> no<br />

irrigation at all (Chevalier et al.<br />

2001).<br />

Weed M<strong>an</strong>agement<br />

Weed m<strong>an</strong>agement c<strong>an</strong> be a more<br />

or less persistent concern dur<strong>in</strong>g<br />

the orchard establishment period,<br />

but as c<strong>an</strong>opy closure occurs <strong>in</strong><br />

<strong>Burgundy</strong> truffle orchards, weed<br />

populations usually decl<strong>in</strong>e. As<br />

the <strong>Burgundy</strong> truffle spreads with the develop<strong>in</strong>g<br />

root systems, its mycorrhizae have a somewhat<br />

allelopathic effect on surround<strong>in</strong>g vegetation,<br />

produc<strong>in</strong>g a characteristic “burnt” zone (with<br />

reduced vegetation) on the pl<strong>an</strong>tation floor.<br />

Dur<strong>in</strong>g pl<strong>an</strong>tation establishment (pre-fruit<strong>in</strong>g), a<br />

variety of mulch<strong>in</strong>g materials c<strong>an</strong> be used to suppress<br />

weed growth. Zambonelli et al. (2005) found that<br />

black water-permeable weed barrier fabric served<br />

well <strong>an</strong>d favored <strong>Burgundy</strong> truffle establishment.<br />

Alternatively, the herbicides Roundup® (glyphosate)<br />

<strong>an</strong>d Buster® (glufos<strong>in</strong>ate-ammonium) seem to be<br />

well-tolerated by the <strong>Burgundy</strong> truffle fungus,<br />

though care must be taken not to let these herbicides<br />

drift onto tree foliage!<br />

Prun<strong>in</strong>g<br />

Strategies differ subst<strong>an</strong>tially for prun<strong>in</strong>g/shap<strong>in</strong>g<br />

the trees <strong>in</strong> <strong>Burgundy</strong> vs. Périgord truffle pl<strong>an</strong>tations.<br />

Prun<strong>in</strong>g strategies for the <strong>Burgundy</strong> truffle focus on<br />

early production of shade, the exact opposite of the<br />

focus <strong>in</strong> Périgord truffle pl<strong>an</strong>tations. Yet even though<br />

shade is the early objective, so also is access to the<br />

pl<strong>an</strong>tation floor for cultivation <strong>an</strong>d eventual harvest<br />

activity.<br />

Harvest<strong>in</strong>g<br />

Interest <strong>in</strong> truffles dates back to <strong>an</strong>tiquity. Greek <strong>an</strong>d<br />

Rom<strong>an</strong> philosophers discussed the nature <strong>an</strong>d orig<strong>in</strong>s<br />

of truffle fruit<strong>in</strong>g bodies. It was variously suggested<br />

Hum<strong>an</strong>s have<br />

long depended on<br />

<strong>an</strong>imals to detect<br />

the location of<br />

truffles. People<br />

have relied on the<br />

natural relationships<br />

of truffles with pigs <strong>an</strong>d even with certa<strong>in</strong> w<strong>in</strong>ter-active<br />

flies. More recently, dogs have become most popular<br />

because they are easily tra<strong>in</strong>ed <strong>an</strong>d less <strong>in</strong>terested <strong>in</strong> eat<strong>in</strong>g<br />

the truffles. The breed of dog does not matter as much<br />

as the <strong>in</strong>dividual dog’s ability to focus on the task at h<strong>an</strong>d<br />

<strong>an</strong>d its eagerness to please its master.<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

14


A more difficult method of search<strong>in</strong>g for truffles<br />

depends on observ<strong>in</strong>g the presence of several species<br />

of fungus fly that rema<strong>in</strong> active dur<strong>in</strong>g cold weather<br />

<strong>an</strong>d lay their eggs <strong>in</strong> the vic<strong>in</strong>ity of ripe truffles. This<br />

method c<strong>an</strong> work well when search<strong>in</strong>g <strong>an</strong> area where<br />

truffles are known to occur. With this method, the<br />

truffle hunter walks very slowly, fac<strong>in</strong>g the sunlight<br />

(to avoid cast<strong>in</strong>g a forward shadow), perhaps gently<br />

wav<strong>in</strong>g a stick, hop<strong>in</strong>g to spot the presence of <strong>an</strong>y<br />

truffle flies. Once a truffle fly has been flushed from<br />

the soil surface, the hunter c<strong>an</strong> search for tell-tale<br />

cracks <strong>in</strong> the soil result<strong>in</strong>g from the rapid growth of a<br />

truffle. The truffle hunter may also resort to sniff<strong>in</strong>g<br />

a h<strong>an</strong>dful of soil to verify the presence of a truffle<br />

before carefully search<strong>in</strong>g with a trowel-like tool.<br />

Above: This <strong>Burgundy</strong> truffle<br />

(<strong>in</strong>side the circle) formed just<br />

below the soil surface at the<br />

base of a cluster of Europe<strong>an</strong><br />

hazel stems on the<br />

Baltic isl<strong>an</strong>d of Gotl<strong>an</strong>d (Sweden). Bottom <strong>in</strong>set: A collection<br />

of <strong>Burgundy</strong> truffles fresh from the woods before cle<strong>an</strong><strong>in</strong>g<br />

with a toothbrush. Top <strong>in</strong>set: This truffle (<strong>in</strong>side the circle)<br />

formed 6 <strong>in</strong>ches below the soil surface. The tool used to<br />

excavate it is one of m<strong>an</strong>y designs; but more import<strong>an</strong>t th<strong>an</strong><br />

the design is the care taken <strong>in</strong> us<strong>in</strong>g it so as not to damage<br />

the truffle dur<strong>in</strong>g excavation.<br />

that truffles orig<strong>in</strong>ated dur<strong>in</strong>g thunderstorms when<br />

lightn<strong>in</strong>g struck damp earth or were somehow the<br />

work of the devil. It’s hard to know exactly how or<br />

when hum<strong>an</strong> attention was first drawn to truffles,<br />

but it almost certa<strong>in</strong>ly <strong>in</strong>volved observations of wild<br />

<strong>an</strong>imals search<strong>in</strong>g naturally for these delicacies.<br />

Perhaps hum<strong>an</strong> attention was first drawn to the<br />

<strong>Burgundy</strong> truffle through observation of the root<strong>in</strong>g<br />

activities of wild hogs, which are naturally attracted<br />

by the truffle fragr<strong>an</strong>ce. It is well known that one<br />

of the pr<strong>in</strong>cipal volatile compounds produced by<br />

ripe truffles is very similar to one of the mat<strong>in</strong>g<br />

hormones produced by male hogs. As a result, the<br />

first domesticated <strong>an</strong>imals used to search for truffles<br />

were undoubtedly female hogs. Unfortunately, hogs<br />

appreciate the flavor of truffles at least as much<br />

as do hum<strong>an</strong>s, so it was very import<strong>an</strong>t to muzzle<br />

your pig before you arrived at the truffle site. Also,<br />

it could be difficult to keep the whereabouts of<br />

your special truffle patch secret if you were seen<br />

tr<strong>an</strong>sport<strong>in</strong>g a pig.<br />

By the 17th century, for several reasons, dogs<br />

replaced hogs as the truffle-hunt<strong>in</strong>g <strong>an</strong>imal of choice.<br />

Most dogs have a sense of smell adequate to detect<br />

the presence of a <strong>Burgundy</strong> truffle 6 <strong>in</strong>ches below<br />

ground at a considerable dist<strong>an</strong>ce. The ma<strong>in</strong> factors<br />

seem to be the dog’s attention sp<strong>an</strong> <strong>an</strong>d eagerness<br />

to please its master. Experienced truffle hunters<br />

have their <strong>in</strong>dividual preferences of breed: Labrador<br />

retrievers, Britt<strong>an</strong>y sp<strong>an</strong>iels, poodles, mixed breeds,<br />

etc. There is even a highly respected breed, the<br />

Itali<strong>an</strong> lagotto romagnolo, which has been developed<br />

specifically for truffle hunt<strong>in</strong>g.<br />

There are various methods for tra<strong>in</strong><strong>in</strong>g dogs to<br />

search for truffles. Some people tra<strong>in</strong> their dogs by<br />

feed<strong>in</strong>g them truffles, but this has the undesirable<br />

result of reduc<strong>in</strong>g the harvest. It’s far better to tra<strong>in</strong><br />

a dog with a unique but different reward that is<br />

only given for the discovery of a truffle <strong>in</strong> the field.<br />

Typically dogs will be tra<strong>in</strong>ed us<strong>in</strong>g a very limited<br />

<strong>an</strong>d unique vocabulary that the dog associates solely<br />

with the truffle hunt. Words such as “Cherche!” or<br />

“Syk!” (Search!), “Ou est la truffe?” (Where’s the<br />

truffle?), etc. Dur<strong>in</strong>g the off-season, dogs c<strong>an</strong> be<br />

tra<strong>in</strong>ed to f<strong>in</strong>d objects flavored with commercially<br />

available truffle oil.<br />

The commercial value of a truffle is closely l<strong>in</strong>ked<br />

to its fragr<strong>an</strong>ce <strong>an</strong>d maturity. All the <strong>an</strong>imal-based<br />

methods presented above depend on truffle fragr<strong>an</strong>ce<br />

<strong>an</strong>d thus have the adv<strong>an</strong>tage of discover<strong>in</strong>g only<br />

truffles that have at least begun to mature. Once<br />

a dog has <strong>in</strong>dicated the location of a truffle, the<br />

<strong>an</strong>imal’s attention needs to be diverted so as not to<br />

damage the truffle. The hunter then uses a metal<br />

tool to gently probe the soil <strong>in</strong> search of the buried<br />

15<br />

www.centerforagroforestry.org


treasure. If the truffle is not found close to the soil<br />

surface, the hunter may hold a h<strong>an</strong>dful of soil to the<br />

nose <strong>in</strong> <strong>an</strong> effort to confirm the tell-tale fragr<strong>an</strong>ce of a<br />

nearby truffle. The hunter also may ask the <strong>an</strong>imal to<br />

reaffirm the truffle’s location. The fragr<strong>an</strong>ce of a ripe<br />

truffle c<strong>an</strong> travel through the soil by me<strong>an</strong>s of worm<br />

tunnels or cracks, caus<strong>in</strong>g the dog to mis-identify the<br />

location of the nearby truffle.<br />

In cultivat<strong>in</strong>g valuable truffle species, one should<br />

be prepared to discover fruit<strong>in</strong>g by other truffle<br />

species native to the area (Chevalier <strong>an</strong>d Frochot<br />

1997; Pruett et al. 2008; Bruhn et al. 2009; Wedén et<br />

al. 2009). Field guides exist that help identify these<br />

native truffle species (Trappe et al. 2007, Trappe et al.<br />

2009). One shouldn’t feel discouraged to learn that<br />

one’s pl<strong>an</strong>tation is shared by native truffle species. It<br />

would be unrealistic to expect the <strong>Burgundy</strong> truffle<br />

to be the only truffle species well adapted to one’s<br />

pl<strong>an</strong>tation site. The import<strong>an</strong>t po<strong>in</strong>t is to keep track<br />

of the survival of the <strong>Burgundy</strong> truffle fungus <strong>in</strong> the<br />

pl<strong>an</strong>tation. However, studies with the Itali<strong>an</strong> white<br />

truffle (T. magnatum Vitt.) have shown surpris<strong>in</strong>gly<br />

that successful fruit<strong>in</strong>g does not depend on T.<br />

magnatum dom<strong>in</strong><strong>an</strong>ce of the mycorrhizal community<br />

(Bert<strong>in</strong>i et al. 2006).<br />

In some places truffles are harvested by such me<strong>an</strong>s<br />

as rak<strong>in</strong>g the forest floor (without the selective benefit<br />

of <strong>an</strong> <strong>an</strong>imal’s nose). This results <strong>in</strong> the harvest of<br />

truffles <strong>in</strong> all states of maturity (<strong>an</strong>d value), <strong>an</strong>d may<br />

even damage the forest floor.<br />

Cook<strong>in</strong>g with truffles:<br />

Advice on fundamentals<br />

• It is preferable to eat truffles fresh.<br />

• <strong>Truffle</strong>s are a condiment; not just a decoration.<br />

• <strong>Truffle</strong>s lose their fragr<strong>an</strong>ce with prolonged or<br />

excessive heat. Different species of truffles have<br />

different degrees of thermolability.<br />

• To impart the best fragr<strong>an</strong>ce to a dish, capture<br />

the truffle’s fragr<strong>an</strong>ce <strong>in</strong> a fatty subst<strong>an</strong>ce: butter,<br />

cream, cheese, egg yolks, oil.<br />

• Capture of fragr<strong>an</strong>ce requires at least overnight.<br />

• Fats of <strong>an</strong>imal orig<strong>in</strong> best capture truffle<br />

fragr<strong>an</strong>ce.<br />

• Use simple preparations that avoid other strongly<br />

flavored <strong>in</strong>gredients.<br />

• Pl<strong>an</strong> for 1/3-1/2 oz. <strong>Burgundy</strong> truffle per serv<strong>in</strong>g.<br />

Recipes<br />

<strong>Burgundy</strong> <strong>Truffle</strong> Omelette<br />

Christ<strong>in</strong>a Wedén<br />

6 medium-size <strong>Burgundy</strong> truffles<br />

1 dozen large fresh eggs<br />

1 cup whole milk<br />

Olive oil for cook<strong>in</strong>g<br />

Salt <strong>an</strong>d pepper to taste<br />

1 day <strong>in</strong> adv<strong>an</strong>ce: Place 5 truffles <strong>an</strong>d<br />

the fresh eggs <strong>in</strong> a large glass jar <strong>in</strong><br />

the refrigerator.<br />

Grate 1 truffle <strong>in</strong>to the milk <strong>in</strong> a glass<br />

jar, <strong>an</strong>d refrigerate.<br />

At the last m<strong>in</strong>ute: Beat eggs with truffle-<strong>in</strong>fused milk,<br />

<strong>an</strong>d pour <strong>in</strong>to p<strong>an</strong> lubricated with olive oil over low<br />

heat, <strong>an</strong>d cover.<br />

Just before fold<strong>in</strong>g, place th<strong>in</strong> slices of the 5 truffles<br />

down the center of the omelette.<br />

Serve immediately.<br />

<strong>Burgundy</strong> <strong>Truffle</strong> Butter<br />

Anonymous<br />

One-quarter pound butter<br />

As much as one-half the volume <strong>in</strong> fresh <strong>Burgundy</strong><br />

truffle<br />

1 day <strong>in</strong> adv<strong>an</strong>ce: Grate the truffle <strong>in</strong>to the butter at<br />

room temperature.<br />

Mix thoroughly <strong>an</strong>d refrigerate.<br />

At the last m<strong>in</strong>ute: Toast slices of white baguette.<br />

Spread with truffled butter.<br />

Top with a th<strong>in</strong> slice of fresh truffle if available, <strong>an</strong>d<br />

serve immediately.<br />

<strong>Burgundy</strong> <strong>Truffle</strong>d Brie<br />

Anonymous<br />

A wedge of brie<br />

Sliced truffle<br />

Water crackers or sliced white baguette<br />

1 to 7 days <strong>in</strong> adv<strong>an</strong>ce: Slice brie <strong>in</strong> half horizontally.<br />

Cover lower half of brie with a s<strong>in</strong>gle complete layer<br />

of th<strong>in</strong>ly-sliced truffle.<br />

Replace upper half of brie, enclose <strong>in</strong> plastic or glass,<br />

<strong>an</strong>d refrigerate.<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

16


At the last m<strong>in</strong>ute: Allow truffled brie to come to<br />

room temperature.<br />

Slice onto warm crackers or toasts, <strong>an</strong>d serve immediately.<br />

Fresh-frozen <strong>Truffle</strong>d Olive Oil Toasts<br />

Christ<strong>in</strong>e Fischer<br />

Fresh truffles dipped <strong>in</strong> olive oil <strong>an</strong>d frozen<br />

Olive oil for <strong>in</strong>fusion<br />

White bread toasts<br />

1 day <strong>in</strong> adv<strong>an</strong>ce: Thaw truffles, slice <strong>in</strong>to olive oil,<br />

<strong>an</strong>d refrigerate.<br />

At the last m<strong>in</strong>ute: Br<strong>in</strong>g olive oil <strong>an</strong>d truffle slices to<br />

room temperature.<br />

Toast white bread, brush with truffled olive oil <strong>an</strong>d<br />

top with a th<strong>in</strong> truffle slice.<br />

Serve immediately.<br />

Additional Resources on <strong>Truffle</strong> Biology,<br />

<strong>Cultivation</strong>, <strong>an</strong>d Cuis<strong>in</strong>e<br />

Cookbooks<br />

Czarnecki, J. 1995. A Cook’s Book of Mushrooms.<br />

Artis<strong>an</strong>. New York.<br />

Hurst, J., <strong>an</strong>d L. Rutherford. 1991. A Gourmets Guide<br />

to Mushrooms <strong>an</strong>d <strong>Truffle</strong>s. HP Books, Los Angeles.<br />

Meunier, G., <strong>an</strong>d Y. Schweitzer. 2010. Les Truffes de<br />

Lorra<strong>in</strong>e. Lorra<strong>in</strong>e Consell Régional. (<strong>in</strong> French).<br />

Wheeler, S. 1999. The Complete Mushroom Cookbook.<br />

Anness Pub., Ltd, London.<br />

Internet Resources: Consult<strong>an</strong>ts <strong>an</strong>d Information<br />

Agri-Truffe. http://www.agritruffe.eu/<br />

Garl<strong>an</strong>d <strong>Truffle</strong>s. http://www.garl<strong>an</strong>dtruffles.com/<br />

New World Truffières, Inc. http://truffletree.com/<br />

Internet Resources: Events<br />

The Oregon <strong>Truffle</strong> Festival. http://www.oregontrufflefestival.com/<br />

Internet Resources: Forest M<strong>an</strong>agement<br />

University of Missouri Forestry Extension: http://extension.missouri.edu/explore/agguides/forestry<br />

Forest M<strong>an</strong>agement for L<strong>an</strong>downers, Missouri Department<br />

of Conservation: www.mdc.mo.gov/forest/<br />

library/<br />

Optimum site conditions for North Americ<strong>an</strong> tree<br />

species, United States Forest Service: www.na.fs.fed.<br />

us/spfo/pubs/<br />

silvics_m<strong>an</strong>ual/table_of_contents.htm<br />

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Bourgogne: un nouveau pari qui concerne les forestiers.<br />

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French)<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

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Wehrlen, L. 2009. Mieux pl<strong>an</strong>ter! La technique “3B”<br />

élim<strong>in</strong>e la végétation et décompacte le sol en une<br />

seule opération. INRA, ONF, RDV techniques n’r<br />

25/26:7-12. (<strong>in</strong> French)<br />

Wehrlen, L., G. Chevalier, G. Bes<strong>an</strong>çon, <strong>an</strong>d H.<br />

Frochot. 2009. <strong>Truffle</strong> cultivation-forestry: A new<br />

strategy to produce the <strong>Burgundy</strong> truffle (Tuber unc<strong>in</strong>atum<br />

Chat<strong>in</strong>). 5th International Workshop on Edible<br />

Mycorrhizal Mushrooms, Chuxiong, Yunn<strong>an</strong>, PRC,<br />

27-29 August 2007. Acta Bot<strong>an</strong>ica Yunn<strong>an</strong>ica, Supplement<br />

XVI :97-99.<br />

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I.R. Hall. 2005. Effect of mulch<strong>in</strong>g on Tuber unc<strong>in</strong>atum<br />

ectomycorrhizas <strong>in</strong> <strong>an</strong> experimental truffière.<br />

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33:65-73.<br />

DVDs<br />

<strong>Agroforestry</strong> Five-<strong>Practice</strong>s DVD (Forest Farm<strong>in</strong>g<br />

section). The Center for <strong>Agroforestry</strong> at the University<br />

of Missouri. Available for purchase onl<strong>in</strong>e at http://<br />

www.centerforagroforestry.org/pubs/<strong>in</strong>dex.asp#dvd<br />

Org<strong>an</strong>izations<br />

The North Americ<strong>an</strong> Mycological Association: Includes<br />

<strong>an</strong> <strong>an</strong>nual directory, a bimonthly newsletter,<br />

<strong>an</strong>d the <strong>an</strong>nual journal Mcilva<strong>in</strong>ea. http://www.<br />

namyco.org/<br />

The Mushroom Council: Market<strong>in</strong>g <strong>an</strong>d consumer<br />

trend <strong>in</strong>formation. http://www.mushroomcouncil.org/<br />

The North Americ<strong>an</strong> Trufl<strong>in</strong>g Society. http://NA-<br />

TRUFFLING.ORG/<br />

19<br />

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Produced by The Center for <strong>Agroforestry</strong><br />

at the University of Missouri<br />

Shibu Jose, Ph.D., Director<br />

203 ABNR Columbia, MO 65211<br />

Technology Tr<strong>an</strong>sfer <strong>an</strong>d Outreach Unit<br />

Michael Gold, Ph.D., Associate Director<br />

Larry D. Godsey, Ph.D., Economist<br />

Dusty Walter, Technical Tra<strong>in</strong><strong>in</strong>g Specialist<br />

Julie Rhoads, Events Coord<strong>in</strong>ator<br />

Michelle Hall, Sr. Information Specialist<br />

For more <strong>in</strong>formation, visit www.centerforagroforestry.org<br />

(573) 884-2874; musnragroforestry@missouri.edu<br />

This work was funded through the University of Missouri Center for <strong>Agroforestry</strong> under cooperative agreements 58-6227-<br />

5-029, 58-6227-2-008 <strong>an</strong>d 58-6227-5-028 with the United States Dept. of Agriculture (USDA) Agricultural Research<br />

Service. Special recognition is given to the USDA, ARS, Dale Bumpers Small Farm Research Center, Booneville, Ark. Any<br />

op<strong>in</strong>ions, f<strong>in</strong>d<strong>in</strong>gs, conclusions, or recommendations expressed <strong>in</strong> this publication are those of the author(s) <strong>an</strong>d do not<br />

necessarily reflect the view of the USDA.<br />

The Center for <strong>Agroforestry</strong> at the University of Missouri<br />

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