Truffles (Tuber melanosporum)

How well established is this crop?

This is a very new crop to the Otago region, although some oak based truffles have been planted for over 10 years. The plants should grow but information on markets, commercial returns, current growers, and any form of regional research may be difficult to find.

Background

Truffles are considered by many to be the ultimate edible fungi and have created a huge amount of interest in New Zealand in the past 10 years. This is mainly due to the work of Ian Hall who was working as a scientist for Crop and Food Research. He worked out a way of inoculating oak and hazelnut trees with the truffle fungus, short-cutting a natural process that people have been trying to copy for years.

Climate

Truffles grow naturally in the hills of Southern France and Italy. An area known for warm summers and cold winters. However, commercial truffieres (a truffle plantation) have been established in a range of climates in New Zealand from Alexandra through to near Auckland.

Winter Chilling and Frosts

Winter chilling and frosts do not affect truffles as they develop beneath the ground.

Rainfall and Irrigation

Truffles do need rainfall or irrigation to grow successfully. Without it yields will decrease. The host trees may need irrigation early in their establishment, but after they are growing, natural rainfall should be sufficient.

Wind

Truffles are not affected by wind but the host trees may benefit from shelter if a truffiere is being established. This is especially important for hazelnuts.

Soil

The soil is the key for truffle development. They require a limestone rich and therefore alkaline soil to develop. If the soil is not like this, large amounts of lime can be incorporated to mimic natural soils.

Fertility

The fertility of the soil will not hinder the development of the truffle, but it can have an impact on the growth of the host trees.

Weed Control

During tree establishment weed control is essential. This can be achieved with regular mowing or even the use of herbicides. Without this the young trees will struggle with competing weeds.

Before fruiting the truffle fungus manages to kill all the weeds round the base of the tree. This is a good sign that truffles are about to be produced.

Varieties

The most desirable truffle species is the Perigord Black truffle (Tuber melanosporum) other fungal species producing similar looking fruiting bodies are the winter truffle (Tuber brumale) and the summer truffle (Tuber aestivum).

Pests and Diseases

The main potential pest problem in a truffiere is other fungal species competing for space on the roots of the host tree. It is not common for insects to affect the truffles but there is some anecdotal evidence that either slaters or snails are affecting plantings in Gisborne.

Layout

The layout of a truffiere is usually dependant on the host trees being used. Hazelnuts can be planted in rows 5m apart and trees spaced 3m within each row. Oaks are planted on a much larger grid pattern of 10m x 10m.

General Management

Truffles are the ultimate slow crop. After planting you may have to wait over 10 years before truffles are produced. During this time the trees must be maintained depending on species. For oaks this is relatively straightforward but for hazelnuts this will mean removing suckers regularly by hand. As the bark hardens in years 3-4, it is possible to do this using agrichemicals.

Harvest

Truffles fruit in the winter and are usually dug with the help of specially trained sniffer dogs or even pigs. The animal identifies where the truffles are and then the owner carefully digs them out and removes the dirt. Training of these animals in New Zealand is not expected to be an obstacle to the development of the industry. After harvest the truffles needs to be chilled to maintain their shelf life.

Equipment

Large scale truffieres will require all the equipment needed to operate an orchard, such as a tractor, mowers etc. Fungicide sprays should not be used at any stage because the truffle comes from a fungus as well. Harvest will require coolstorage and specially trained animals to hunt out the truffle.

Returns

Returns from New Zealand grown truffles are hard to guess at because none have really reached the international market yet. A few years ago, prices for black truffles in Paris were upwards of $2000/kg. However, recent cooking shows on television such as ‘French Leave’ suggested prices were around NZ$100/kg direct from the truffle hunter in the French countryside. Careful homework around these figures is suggested before planting trees.

Contacts

Crop and Food Research, Invermay

Suggested reading: Hall, I.: Brown, G. 1988 The Black Truffle: Its history uses and cultivation. New Zealand Ministry of Agriculture and Fisheries.

New Zealand Truffle Association website: http://www.southern-truffles.co.nz/