Cultivation of Truffle-infected Plants
This document is a high level overview of the basic requirements and factors involved in commercial cultivation of Truffles. Research is ongoing world wide and we attempt to provide the latest generally accepted points of view. Oyama Gardens, together with New World truffieres, the Truffle Association of BC and University of BC is conducting research on the production of truffles in Canada. With the purchase of trees, we offer ongoing consultation concerning the newest methods and research. Our recommendation is for individuals to do their own research and arrive at their own conclusions about best practices in deciding whether truffles are a reasonable venture.
1. Site Selection
Truffles are an ectomycorrhizal species meaning they grow in a symbiotic relationship with other plants, on the outside of their root systems. As such, they compete with many other ectomycorrhizal species for dominance and survival on host plants. Ideally sites will be free from existing tree growth. Because of our extreme northern latitude, they will also require south west or west facing slopes to obtain the maximum heat units possible. Climatic Requirements Following is a comparison of climate data for local and overseas truffle growing regions; France / Italy New Zealand Duncan Kelowna Saanich Annual Rainfall 600 /1500 1058 mm 993 / 883mm 380 mm mm Mean Daily 17.5° / 22°C 18.7° 16.1°/15.6° 17.3° temp – Summer Mean Daily 1°/ 8°C 9.1° 3.7/3.3° -1.2° temp - Winter Annual 1900/2800 2204 1803/1985 1954 Sunshine hours Summer 1200/1800 1319 1352/1454 1470 sunshine hours (April – Sept) 900/1900 1430 807/761 977/1913 Approximate degree days (10°)
Soil conditions Selected sites should be free draining, well aerated, be sufficiently calcareous (pH value) and deficient in nitrogen. Loess soil is favoured for growing truffles, because it fulfils these conditions. However, it is also possible to grow truffles on light, sandy soil or on chalky soil. The pH value of the soil is one of the most important conditions for viable cultivation of truffles. Ideally, the natural pH value of the soil should range between 7,0 and 8,5. For a pH value below 4,5, truffle production may be inhibited because of aluminium toxicity. If the deviations are small, it is possible to regulate the pH value (raising the soil pH by liming). Optimal conditions are; Ph Depth Surface Organic Matter Plant available Ca, Mg Plant available P Na Drainage Texture Aeration Min 7.5, max 7.9 40 cm 8% High Moderate Low Free Loam, granular Good
The most favourable mineral composition for truffle production varies from soil to soil, and depends on many different factors, such as soil type, soil structure and content of organic matter. Accordingly, it is not possible to specify generally valid conditions. Before establishing a "truffiere" it is absolutely imperative that the soil in question be professionally analyzed and evaluated for its suitability. Both the topsoil (15 - 30 cm) as well as the subsoil (30 - 60 cm) should be examined because they are each vital for the relationship between fungus and host (topsoil) and general root activity (subsoil). Soils with high heavy-metal content are unsuitable for growing truffles, because the development of fruit bodies (truffle formation) will be delayed or even inhibited. In considering an area which has been used intensively for normal agriculture, additional preparation or amendment of the soil may be required since these soils may exhibit a high level of nutrients and / or pesticide residues.
2. Establishing a Truffiere
Preparing the ground In order to aerate the soil and remove the weeds, the soil should first be ploughed to a depth of 30 cm. Irrigation systems should be designed and installed prior to planting, and should include provisions for any future access cultivation, pruning or mowing, or traffic management requirements. Planting - planting time: Autumn (October/November) or March. The truffleinfected plants are delivered either bare root or potted. The trees should be planted together with the entire substrate in the pot, as it is penetrated by the inoculated root system. Typically up to 1000 - 1200 plants/hectare depending on terrain, planting method and the owners desire to take advantage of esthetics, security or other considerations. Approximately 3 - 4 meters distance within and between the rows. Monoculture or mixed cultivations are possible. Alternate planting of seedlings (hazel, oak) within the rows, and hexagonal close packing, is typical. Mixed planting is thought to offer the benefit of stronger vegetation promoting the development of fruit bodies, thereby ensuring earlier and better yields. Cultivation of hazelnut saplings involves more work, as the foliage has an acidifying effect on the soil and must therefore be transported out of the field in fall.
- planting density:
- planting distance:
- planting system:
3. Maintenance and Cultivation Work
Irrigation To encourage proper growth of the truffle-infected trees, thorough moistening of the soil is imperative. In almost all cases, watering is needed during the first few months after planting. Furthermore, supplementary irrigation is advised from the first to the third year. Fields must be irrigated whenever necessary during the whole period of cultivation to increase the yield. Irrigation quantity and frequency vary strongly, depending on the soil type and climatic conditions. Irrigation systems may include: overhead irrigation/sprinklers mini-sprinklers droplet irrigation (spiral irrigation pipes) With regard to irrigation water, the presence of extreme concentrations of minerals or pesticide residues must be excluded. Undesirably high nutrient or pollutant levels may be removed with the aid of an osmosis installation, for example. Soil cultivation and care Typically, cultivation involves rotary tillage. In the fourth and sixth months after planting, at a depth of 3 - 5 cm. In the following years, aeration should occur twice a year in the same manner. The aim in soil cultivation is to aerate the soil and to remove the weeds during the cultivation period. In autumn, the hazel foliage must be taken out of the plantation, because otherwise it would acidify the soil (i.e. reduce the pH value). Whenever necessary, correction of the soil pH (liming) should be carried out. Fertilization: If necessary, manure may be added to raise the levels of organic matter in the plantation and to stabilize the soil moisture content. A mixture of vegetable and animal products should be added, with pH < 8 and carbon/nitrogen ratios about 10 or more. Plant protection Damage can be caused by deer, marmots, hares, rabbits, mice or squirrels and ideally the truffiere should be completely enclosed. Fencing may also be
necessary to prevent theft of the truffle. Young plants should be shielded from sunburn and wind damage. Pruning Truffle trees are pruned in an upside down cone shape to obtain the maximum number of heat and light units on the soil surface. Conversely, commercial hazelnut orchards are pruned in an upside down umbrella shape to keep roots moist and soils cool, and to obtain maximum light on the trees canopy. Tree Threats Parasites may include Leaf-rolling caterpillars, aphids, and truffle fly (Suilla gigantae, formerly Heliomyza tuberivora) which are a problem in France and Italy. There are no known insect threats to truffles in North America. Fungal diseases of the host plants can include Powdery Mildew, for example. Lifecycle of a Truffle Hazelnuts should begin to produce fruiting bodies within 5 – 8 years of planting. Oaks begin to produce somewhat later, around 7 to 10 years. Hazelnuts can be expected to support truffle production for up to 25 years, while Oaks are thought to continue producing for up to 100 years. Please see the attached diagram for a description of the reproductive cycle.
Harvest methods: Pigs (used traditionally because of their natural sense of smell and general availability on rural farms, are no longer used as they tend to eat the truffles. Dogs (specially trained) are frequently used in newly established truffieres. Mature truffles are indicated by cracks in the soil (but only in light soils) Observation of brule’s on the soil surface. Careful digging with a hand shovel. Electronic detectors, “sniffing devices” Harvest time Summer truffle (T.aestivum Vitt.) - Summer (June - July) Burgundy truffle (T, uncinatum Vitt.) - Summer (June – July) Perigord truffle (T.melanosporum Vitt.) - Winter (November - March)
Yields Yield is based largely on efficient and careful management of the truffiere including cultivation, irrigation and a certain amount of mystery. In Italy, T. Melanosporum production is reported to reach 50-60 kg per year or even up to 80–100 kg per year in well managed truffieres. Research is ongoing regarding methods of improving and accelerating initial and later production. Prices (2006) Summer Truffle Perigord Truffle, Fresh* $825 US$/kg $4,752 US$/kg
Source; Marky’s – http://www.markys.com/caviar/customer/product.php?productid=16606&ca t=506&page=1 Note; These are retail prices, and include a 100% tariff on imported truffles imposed by the US government. Due to the market being infested with T. indicum, T. sinensis and other undesirable truffles, reliable and reputable importers of truffles are few and far between and thus command a premium for actually providing what they say they are selling a specific truffle. Characteristics of common truffle types Summer-Truffle: (T. aestivum) Burgundy Truffle (T. uncinatum) Perigord Truffle: (T. Melanosporum) Italian White Truffle (T magnatum) Flavour weaker than the White Italian and Perigord truffles, but earlier and higher yields, sold fresh and tinned.
strong flavour, sold fresh, high price
Rarest and possible most desirable Strong flavour, light coloured flesh and slightly different texture than Perigord truffle. Weak flavour yet same texture and similar in appearance to Perigord truffles. Often used as a filler to increase the size of preserved truffle products. Considered a “weed” truffle.
Chinese truffles (T. brumali) (T. sinensis) (T. indicum):
5. Sale of Truffles
Oyama Gardens is developing a wholesale distribution company which will purchase all truffle production from Canadian producers. Producers may also combine their products with culinary and agritourism ventures either alone or in cooperation with other local producers of artisan food products such as oils, cheeses, and other processed food products.