By Theresa Garner
HAMILTON - Environmental watchdogs are letting people grow a banned noxious weed as a medicinal herb.
St John's wort, acclaimed as a cure for depression, is one of 110 plants banned from sale or distribution in New Zealand.
If eaten by livestock it can cause photosensitisation - oversensitivity to light.
The
regional council Environment Waikato has granted an exemption to a Hamilton herb grower to produce the poisonous weed commercially.
It has followed the lead of councils in the Bay of Plenty, Hawkes Bay and Canterbury, which have allowed growers to plant and harvest the plant under strict conditions.
Natural therapist Katrina Johnson, who won the exemption for her Koromatua garden, on the outskirts of Hamilton, described the herb as "a natural equivalent to Prozac."
The yellow-flowered perennial, Latin name Hypericum perforatum, is also used to treat skeletal and viral problems.
Last year in the United States, 7.5 million people used St John's wort, which is available without prescription from health food shops and supermarkets.
Although some studies have questioned its effectiveness and effect on fertility, it is also popular in Europe.
The plant is the leading treatment for depression in Germany - doctors there write 25 per cent more prescriptions for it than for Prozac.
Most health food shops stock it and several New Zealand companies produce varieties such as concentrated extracts for the herbal antidepressant market and external rubs for skin and muscle repair.
Scientists at Crop and Food Research are studying the crop and have found good levels of the active ingredients, dianthrones, in St John's wort growing wild in Central Otago.
Researcher Malcolm Douglas said farmers throughout the country had inquired about growing the crop.
He said returns were good at $10 a kilogram of dried plant. Farmers were able to get a tonne of dried heads a hectare.
But there was major international competition. Last year New Zealand's production was estimated to be up to 10 tonnes, while Chile produced 1000 tonnes.
