New Zealand truffle growing industry

October 2006
The NZ truffle industry is poised for substantial growth, with over 100 truffires (truffle plantations) already established, from small lifestyler and hobby farms, to large commercial plantations of up to 8000 trees.

Only 9 truffires are currently producing truffles and these are all sold into the local market, but a new commercial nursery operation looks set to stimulate a rapid expansion in trees planted - and a few years down the line, a rapid expansion of crop - leading to multi-million dollar exports.

A truffle is an edible mushroom which fruits under the ground, growing in association with the roots of oak and hazel trees that have been infected with the truffle fungus. Perigord black truffles, known to scientists as Tuber melanosporum, are prized for their unique flavour and intoxicating smell. They vary in size, from golfball to baseball (and larger), and look like a cross between a shrivelled avocado fruit and a lump of coal. Their texture is succulent and firm and they have been called the undisputed sovereign of all gourmet foods.

Truffle plantations produce one crop per year between May and August in the Southern Hemisphere and December to March in the Northern Hemisphere. They usually start producing truffles within five to ten years from planting, with good commercial quantities normally available two to three years after first production.

NZ market price for the last two seasons has been stable at $3,500/kg. Individual truffles usually range in weight from 10g - 300g - though they can sometimes reach 1kg. They usually grow in the top 30cm of the soil, and though you can sometimes spot growing truffles as they push the soil above them upwards into little mounds or volcanoes, trained dogs are used to harvest them. They must be left undisturbed to form and mature, so soil and root disturbance during summer and autumn is a no-no.

New Zealand has great potential as a truffle producing and exporting nation, because Southern hemisphere production is in the Northern Hemisphere off-season, and truffles do not preserve/freeze well. The fresh product is the premium product. NH production (in France, Spain and Italy) ranges from 20 - 100 tonnes depending on seasonal factors, and is sold around the world. Target markets for NZ-grown black truffles are the top restaurants, hotels and lodges in Europe, North America, the Middle East and Asia. China already has its own domestic truffle industry, based on a similar, but less valuable truffle.

The NZ industry has been fostered by Crop & Food Research, and in particular by former CFR scientist Dr Ian Hall, who introduced black truffles to NZ in the late 1980s. His brother, Alan Hall, from Gisborne, was the first person in the southern hemisphere to produce black truffle, back in 1993. Ian Hall and his team have also successfully introduced the Burgundy truffle and the bianchetto (a white truffle) which produced its first fruit earlier this year.

The NZ Truffle Association was formed in 1990 and represents more than 150 growers. It is the recognised product group under the Horticulture Export Authority, and sets quality standards and licenses exporters. It also conducts research on behalf of growers, recently commencing a $200,000 project with CFR, funded through the Foundation for Research Science and Technology.

Welshman Gareth Renowden and his Kiwi-born wife Camille bought 10ha and the homestead in 1997 and they are now growing truffles, olives and grapes. Gareth is an author, journalist, photographer and publisher, and Camille is a banking consultant. Gareth has recently published The Truffle Book, the first book in English to cover the world of truffles and the truffles of the world. He is also president of the NZ Truffle Association.

He has 210 nine-year-old truffle-infected oak and hazel trees at Limestone Hills, with some experimental areas of oaks, hazels and pines infected with Burgundy and bianchetto fungi. Burgundy truffles fruit in autumn, and bianchetto in late winter, extending the season when fresh truffles are available. The Renowdens found their first truffle in June this year, by accident, although their truffle dog, Peg, is the NZ champion. As an indication of truffles forming under the ground, the pasture cover around the tree trunk tends to die back, producing an area of bare soil called a brul in France (like a crme brul - burnt).

Peggy is trained by burying a film canister with holes punched in it, containing cotton wool and a little truffle oil. She sniffs out the aroma and indicates the place with a scrape of the paw on the ground.

Here is Gareths own description of the industry:

The truffle is an underground mushroom that grows on the roots of specially inoculated trees principally oaks and hazels. These trees have to be raised from seedlings, so the lead-in to production can be anywhere from five to ten years, but yields can then potentially move into six figures per hectare, so its worth the wait. Sadly, mature trees cannot be inoculated successfully.

Before planting, you must ensure that the soil is at the required pH, and if that means adding tons of lime, then get spreading at least a year before you plan to plant. You also need to ensure that the soil the trees are going to grow in is well cultivated and sprayed free of grass before the little trees go into the ground.

Unlike most crops, in the truffire the aim is grow dense, active root systems, because thats where the fungus lives. The more roots, the more truffle. Once the trees are growing, the annual maintenance involves late winter pruning (hazels are prone to suckering), a spring cultivation of the soil on either side of the rows of trees before bud burst to keep the soil loose and stimulate new root growth, and continual control of grass and weeds. Fortunately, once the trees are growing well, they should form a brul, or region of bare earth around the tree a sign that the fungus is doing well.

From mid-summer, watering becomes important, and the soil should be kept reasonably moist throughout the autumn. Truffles should begin to ripen from May onwards, and then its time to get your highly trained truffle hound into action. A properly trained dog is essential for any truffle grower, because the aroma of a fresh truffle, while strong, is a bit difficult for humans to smell through damp earth.

Former sheep farmer Bill Lee, Gebbies Valley, Banks Peninsula, is now a partner in a two truffieres at Ohoka, North Canterbury and at Mangawhai, Northland. He is also a partner with Tasmanian truffle grower Tim Terry in Southern Cross Truffle Nursery Ltd, formed about one year ago. It has an agreement with Crop & Food Research to rent and use the greenhouse facilities where NZs research effort into truffles has been conducted for about 15 years. Terry also has a nursery in Tasmania, plus about 40,000 trees growing. The commercialisation venture here enables Crop & Food Research to get on with the science (Carolyn Dixon) and earn a research contribution from Southern Cross.

Lee collected 45,000 acorns from evergreen oak trees throughout Canterbury and washed them before laying them down to germinate in a sterile growing medium. All facilities have to be washed with antifungal chemicals to prevent the risk of other competing fungi infecting the germinating acorns. They have to be watered daily and are now growing. There is a 98% germination success. The seedlings will be split out individually and inoculated with the truffle mycorrhiza and growing on for a further four or five months. They will then be available for sale next autumn for prices between $40 and $50, depending on quantity. If all are sold and planted that would double the size of New Zealands truffieres. Inoculated trees have been available in small numbers until now. Lee says there is a significant chunk of intellectual property in the tree seedling price. Southern Cross has to import truffles from the northern hemisphere, and develop get a spore mix and apply to the roots when transplanting. Crop & Food Research is providing quality assurance that the seedlings are confirmed as inoculated.

Plantings of truffieres in the future should be more targeted and deliberate, Lee said, with soil analysis of pH, soil texture and attempts to find competing fungi. Acid soils might need anything up to 50T of lime per hectare to raise the pH to the optimum 7.9 to 8. They will need a watering system, ongoing management care and a trained dog for the harvesting. Many more truffles are grown in New Zealand than are found, Lee said.

If NZ had 500,000 to 600,000 trees, which would be 1200 to 1500ha, only one quarter of the planted area to avocados, then truffle production of 30 tonnes annually could be confidently expected, Lee said. This would generate up to $90 million in export earnings, three times that of the avocado industry.

Southern Cross has already received confirmed orders for 10,000 trees next autumn and could expand production to 100,000 trees if there is the demand.

Quite small truffieres can be very productive, at 400 trees/ha, generating perhaps $60,000 to $100,000 annually. This would be the highest returning land use in New Zealand.

The suitable soils are free-draining, which would include ash soils, possibly gravely and those from limestone origin. The mycelium of the fungus can spread through the soil readily.


The Truffle Book by Gareth Renowden

New Zealand Truffle Association website: