There are three acknowledged New Zealand truffieries producing this subterranean fungal delicacy, one in Canterbury and two in the North Island. But for security reasons, no one is saying where the truffles are.
Such is the stigma surrounding this potential black gold. Usually fetching $NZ500 to $NZ2,000 per kilo, first grade truffles occasionally retail for $7,500 in London, while in a Tokyo shop tinned truffles once sold for $NZ22,000 per kilo. The world retail market for Perigord black truffle has been estimated to be around $500 million.
Truffles grow in a symbiotic relationship with trees because they cannot produce their own food. Trees such as oaks, hazel nuts, birches, pines and furs are all suitable partners for the mycorrhizae fungi. The hyphae coat the roots of the host tree helping their host to absorb soil minerals. In return, the tree host provides the fungus with carbohydrates and other nutrients, the product of the trees photosynthesis.
Truffles have been collected for at least 3,600 years and the 1-7cm fruiting body is usually round and pitted with an appearance not unlike an avocado. The flesh of all truffles is nearly white when young but becomes darker with a marbling of lighter tissue as it matures.
This mycotic nugget has an intense and distinctive smell containing steroidal compounds very similar to sexual hormones and some human pheromones. It certainly gets the pigs going, which have traditionally been used to find the buried delicacy, so much so that trained dogs are now generally used so as not to destroy and eat the precious orbs.
According to New Zealand's premier expert on truffles, Dr Ian Hall of Crop and Food Research in Mosgiel the optimum requirements for a black truffle truffiere are warm summers and cool winters, a free draining, high pH well aerated soil with a well defined structure, irrigation, and the absence of other trees that may have competing fungi on their roots.
Does the crop offer potential for in the top of the South Island ? "Yes," Dr Hall said, "truffles have recently been found in Canterbury as well as in the North Island. However, the area planted should be a warm north facing area with the right soil conditions and irrigation."
Dozens of immature Perigord black truffles have been found at a Gisborne truffiere, the same truffiere which produced the first example in the southern hemisphere in 1993 and a sizeable area of New Zealand has already been devoted to the crop.
"About 16,000 trees at 500 to 800 trees per hectare. But at a potential return of 130 kg/ha and an out of season wholesale price of $3 per gram you don't need many hectares to make a useful industry." Dr Hall said.
Dr Tim Ewer of Mapua has seen the potential for the crop and seized the opportunity to plant more trees on his farmlet, where he grows a collection of 160 trees split 2 to 1 hazel and oak that have been specifically infected with the fungi.
"The biggest thing here is the soil conditioning as they require an alkaline soil of about 7.8-7.9, and being Upper Moutere clay the difficulty has been getting the pH up. This has required a huge amount of lime, I'm talking about over the past few years, on just under an acre of land, putting on about 40 tonnes of lime."
"I get the soil tested at least two or three times a year as part of the regular maintenance."
Dr Ewer has had the trees in the ground for five years and with a maturity of the crop from 4-8 years on the hazel trees and 7-8 on the oaks, the anticipation is building.
"It could theoretically happen any time now, you get what's known as a 'brules' around the tree, an area where grass and other weeds wont grow, you get large patches of sterile ground, and a few signs started this year."
The first New Zealand success in black Perigord truffle growing at Gisborne in July 1993 was also heralded with 'brules', 18 months before the first find.
