Sabtu, November 27, 2010

'World's deadliest mushroom' here to stay, expert warns

European death cap likely hitched a ride to Vancouver on a non-native tree

By Larry Pynn, Vancouver Sun November 26, 2010

Paul Kroeger first documented the world's deadliest mushroom a short walk from his home on East 40th Avenue in Vancouver.

It was September 2008 and he spotted a cluster of European death cap mushrooms at the base of a hornbeam tree, a non-native plant used to beautify city streets.

"I always keep an eye open for mushrooms," the vice-president of the Vancouver Mycological Society said Monday. "I had been expecting it to show up."

Kroeger said death cap mushrooms (Amanita phalloides) entered Canada through the roots of non-native trees. They showed up in Mission in 1997 and now are also found on southern Vancouver Island.

Since 2008, he has found death caps at two other east Vancouver sites, also hornbeam trees, evidence that they're here to stay. "They'll probably start popping up all over the place."

If ingested, they pose a serious poisoning threat to people and animals. "It is the most deadly mushroom in the world," Kroeger said. "They take down more people every year than any other mushroom."

Of 42 people poisoned by death cap mushrooms in the U.S. last year, three died, including a California mother of three; her cousin had a successful liver transplant.

In Europe, deaths caps are reportedly responsible for almost 90 per cent of deaths due to mushroom poisoning.

And while there is no stopping the mushroom, Kroeger said it's important to make residents aware of its existence.

Southeast Asians can be especially susceptible because the death cap resembles the paddy straw mushroom commonly eaten in their homelands. "They look very similar," he said.

A mother of two, originally from Thailand, died in England in March after eating the mushrooms with sausages.

The death cap mushroom has a smooth, yellowish-green to olive-brown cap, white gills, white stem, membranous skirt on its stem, and a cuplike structure around the stem base.

Anyone who eats one can expect stomach pains, vomiting and diarrhea. Symptoms typically subside for two or three days before returning, along with jaundice. Without treatment, coma and death can occur due to liver failure and possibly also kidney failure.

The spread of the death cap mushroom coincides with an increase in recreational mushroom picking in the Lower Mainland. Problem is, there are fewer places to pick legally.

"It's harder and harder to find areas where harvesting in permitted," Kroeger said.

Increased interest in recreational harvesting is due to mushrooms being seen as healthy in alternative medicine circles, a trend to eat local and wild foods, and even a desire to save money during tough economic times.

At the same time, Kroeger said, commercial picking has generally declined around the province due to the increased cost of shipping, a drop in prices from buyers such as Japan, and a greater volume of mushrooms from other countries.

Parks at every level prohibit picking of mushrooms, although provincial Crown land is open to picking.

Richard Wallis, acting west area parks manager for Metro Vancouver, said anyone who removes a mushroom from a regional park risks a fine of $100. More likely, however, violators will receive a warning and have their mushrooms confiscated and returned to the forest.

"We want to protect the entire ecosystem," he said.

Local edible varieties that are harvested in fall include chanterelle, oyster, honey, and cauliflower mushrooms. The pine mushroom is also found in drier, mountainous regions.

Louis Lesosky of Wild Products on Granville Island sells 70 wild varieties of mushrooms from B.C. He said consumer demand for wild mushrooms has increased 10-fold over the past decade, with prices ranging between $5 and $40 a pound, depending on availability.

Harvesting fosters greater appreciation and understanding of the environment, including the interrelationship between plants, and is an excellent family activity, he said.

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