They were billed as ''black diamonds'' and an opportunity to get rich quick but it has now emerged that parts of the truffle industry in Australia are in dire straits, with some growers abandoning their orchards.
Mystery surrounds why some truffieres, some having invested tens of thousands of dollars and spent more than 10 years waiting, have produced nothing, with growers in the states of NSW and Victoria the worst affected.
Theories for the failures include inadequate inoculation of tree roots with the fungal spores, unsuitable climate or too much soil acidity.
Victoria last year produced only 40 kilograms of black truffles (Tuber melanosporum) out of a nationwide harvest of 4.5 tonnes.
By some estimates less than a 10th of Australia's 160 growers are getting a commercial harvest.
At the industry's annual conference in Mittagong in August a panel of international experts will consider how to turn around this poor production.
Past president of the Australian Truffle Growers Association Graham Duell, of Jindivick, Victoria, planted 370 oak and hazel trees inoculated with the truffle fungus in 2001. With irrigation and preparation of the land he put the cost at about $30,000. ''I haven't produced a single truffle,'' he said. ''I have had soil tests and root tests which confirm the fungus is alive and well but we just don't get any fruit.''
Asked what he would say to others considering the industry, he said: ''I'd say. 'Don't.' Not until we can demonstrate a return on investment. In my time as president looking at the economic returns for the industry, I can say that almost all of the Australian harvest comes from five or six sites. The majority are hobby farmers with only one or two actually covering their costs.''
Wayne Haslam, of Sutton near Canberra, started the association and planted 900 trees in 2003, and planted a further 900 trees in 2008, but last year harvested only seven kilograms of truffles.
He said he had offered his orchard for use by the researchers and said rather than abandon the project he was interested in learning what was causing the problems.
''There would be 160-plus growers and we would be lucky if 10 per cent of those were getting what could be regarded as a commercial crop,'' he said. Two management investment schemes in Tasmania had been wound up last year, he said, a project in Oberon had stalled and orchards in Orange were not producing commercial crops.
Australian National University senior scientist Celeste Linde said stringent controls governing the inoculation of tree roots with the truffle fungus were needed.
Associate Professor Linde said soil with too much acidity or which had a high phosphate content could also be interfering with fruiting.
''To get truffles from a tree that hasn't produced for 10 years will be extremely difficult because [the spores] on the roots may have started to disappear,'' she said.
Growers association president Anne Mitchell said part of the problem of sporadic and uncertain production was the limited amount of research into cultivation. ''It is one of the few agricultural pursuits where you put a lot of money in, you put a tree in the ground, you do everything you think correctly and there is no guarantee of a product,'' she said.
''We are still working out whether it is climatic, soil or to do with management of trees, or even initial preparation of the trees. We don't know the answers to that yet.''
Australia 4.5 tonnes produced in past year.
WA 3 tonnes.
Tas 800 kilograms – 1 tonne.
NSW 600-800 kilograms.
Victoria 30-40 growers producing 40 kilograms a year.
SA No significant production yet.
Market price last year $900-1100/kg; retail $2500/kg
Source: Australia Truffle Growers Association