An increasing number of shiitake mushroom growers have switched to using imported Chinese growing 'logs' on which the fungi is grown. The reason is that these are cheaper than using New Zealand-made logs.
These logs are actually plastic bags filled with sawdust and water, inoculated with shiitake spawn, and shipped to New Zealand. Other exotic mushrooms such as Enoki are grown in the same way. The mushrooms, harvested just a few weeks after arrival, are then often sold as ‘New Zealand-grown’.
"But the substrate and none of the inputs are from New Zealand. The whole thing is done in China and imported here. New Zealand customers are getting hoodwinked," said Hillcroft Mushrooms co-owner Bruce Mackinnon.
The small Hawke's Bay organic shiitake grower said his sales had fallen "around 80 percent over the last two years" as his competitors switched to cheaper imported growing logs.
Meadow Mushrooms, the country's largest mushroom grower, launched its "New Zealand grown" shiitake mushrooms earlier this month which it said were all grown from Chinese logs. Meadow Mushrooms marketing manager Melanie Rushton said its packaging complied with Australian and New Zealand standards.
"We are not hiding anything ... we are still updating our information about our product that's just launched so we are going to be telling everyone all about the details behind it as well."
Detectable levels of heavy metals
China's poor environmental record raised further concerns for consumers, Mr Mackinnon said. He and Northland shiitake spawn grower Tim Thornewell, from Mushroom Gourmet, collected samples of mushrooms grown on New Zealand and Chinese logs for testing at Massey University.
Only minute levels of arsenic, lead and mercury were detected in the New Zealand mushrooms, but "detectable" amounts of arsenic and lead were found in the Chinese ones, Mr Thornwell told rnz.co.nz.