The code has been developed in response to fears that the increasing vogue for wild mushrooms in restaurants is leading to over-picking, which is harming woodlands and wildlife.
Tasty species such as chanterelles, ceps and horns of plenty, collected with passion in continental Europe but for long left on the ground in the UK, are now fetching British pickers remarkable sums. A recent survey put their retail price per pound in supermarkets and delicatessens at pounds 13, pounds 45 and pounds 85 respectively.
But such handsome rewards have led some collectors and commercial pickers to damage the habitats where the mushrooms grow. They have wiped clean whole areas of wood and forest by picking the inedible as well as the edible species. After subsequent close examination the inedible ones are thrown away. Such practices have led commercial picking to be banned in the New Forest.
The 30-point code, published by English Nature, the Government's wildlife agency, in collaboration with several other conservation organisations, offers guidelines on how to collect and enjoy wild mushrooms in a sustainable way.
It urges pickers to minimise damage to vegetation, leaf litter and soil, not to take rare species, not to pick button mushrooms that have not yet expanded their caps, and to take no more than is wanted for personal consumption. This, it says, should be no more than about three pounds per person per visit, or no more than half the mushrooms of any one species present, whichever is the lower.
The code does not discourage commercial picking but says it should be agreed with the landowner or manager of the site. The code suggests that anyone who wants to pick seriously should attend a course, or a foray - an organised mushroom-gathering expedition.
"Be aware that some fungi are very poisonous and many others may make you unwell," it warns.
In drawing up the code English Nature has enlisted the support of the Forestry Commission, the National Trust, the Woodland Trust, the Association of British Fungus Groups and another expert body, the British Mycological Society.
Antonio Carluccio, owner of The Neal Street Restaurant in London and the capital's best-known enthusiast for wild mushrooms, also gave it his backing. "Take only what you need for personal use and pick only those you are 100 per cent sure about. Don't destroy the poisonous ones," he said.
The return to culinary favour of wild mushrooms in Britain has been a notable, if small-scale, cultural event. Until the Seventies, Britons almost alone of the European peoples paid no heed to their wild fungi, eating only cultivated mushrooms and the common white field mushroom, and using the word "toadstool" for mushrooms they thought inedible. (The two words are in fact entirely interchangeable.)
But a change began in 1972 with the naturalist Richard Mabey's book Food For Free, which showed what culinary riches the countryside offered. It was followed by other cookbooks celebrating wild mushrooms, and then by restaurants putting them on menus.
"There has been an enormous increase in the collection of wild mushrooms in Britain in recent years," said Brian Johnson, English Nature's botanical services manager. "It's partly because people have eaten them in France and other places and want to try them here, and partly because of the publicity given to their culinary value by people like Antonio Carluccio."
It was not certain that mass picking actually harmed the mushrooms themselves, Dr Johnson said, but it did harm the aesthetic qualities of the woodlands they grew in, and the wildlife they supported.
"Wild mushrooms are enjoyed in the autumn by many members of the public who don't wish to pick them, but who see them as part of the surroundings, yet we have had whole areas of the New Forest stripped of everything by eight in the morning," he said. "I've seen a Land Rover full."
Up to 1,000 insect and other invertebrate species depended on wild fungi, he said. "And it's only common sense that if you pick out all the fruiting buds of one particular species year after year, you are very likely to cause local extinctions of the organisms that live on those species."
The mycologists have agreed to the code but are slightly wary of some of its provisions. "The scientific evidence shows that commercial picking is not in fact damaging the numbers of fungi, and we want the code to remain flexible, and not be turned into a law," said Professor Roy Watling, Britain's leading wild mushroom expert.
He retired this summer after working at the Royal Botanic Garden, Edinburgh. Yesterday he was leading 36 cep-fanciers on a foray in Perthshire.
THE EXPERT'S GUIDE TO WILD MUSHROOMS
Common in Britain, often in birch or pine woods. Apricot yellow in colour. The girolle of French restaurants
About pounds 13 per pound
Everybody thinks it tastes like apricots but it doesn't, it just looks like one. A very tender and nice mushroom, but it doesn't have a great deal of flavour; it's very delicate. That's why I serve it often with eggs, so as not to overpower the flavour.
Large chunky mushroom with brown or toast-coloured cap, found in all types of woodland throughout Britain
About pounds 40 per pound
Very robust in taste and texture, more or less the king of mushrooms. The taste - it's heaven. A very earthy taste, a very musty taste, extremely flavoursome and mushroomy. But it's extremely versatile, it can be eaten raw, especially the small ones, with olive oil, lemon and parsley and a pinch of salt. That's fantastic.
A greyish mushroom with an elliptical cap, pitted like a honeycomb. Commoner in Europe than in Britain
About pounds 100 per pound
They are lovely washed. They are hollow and they tend to incorporate everything in the place where they grow, so you have to be careful there aren't little stones inside. Cut the leg and open it. The flavour intensifies when they are dried, and they are the only dried mushrooms that regenerate back to their full original size when soaked.
HORN OF PLENTY
Blackish-brown, found in beech woods, shaped like a narrow trumpet. Trompette de Mort in France
About pounds 85 per pound
Flavour rather like the Chanterelle, almost more delicate. Not full flavoured. It discolours a bit when cooked. I like it particularly with boiled sole or steamed fish.
SAFFRON MILK CAP
Found under conifers. Pale orange cap with darker orange concentric bands. fairly common in Britain
About pounds 13 per pound
That's a delightful one, lovely, but you have to be careful not to confuse it with Lactarius torminosus, which is poisonous.
The common pale wild mushrooms that people find in meadows in the morning, rarer than they once were
Not often on sale
If you don't know what they are, don't pick them. Go with an
expert at first, and go often so you can
recognise one or two, and then gradually go on to recognising more.
These are wonderful, extremely musty and very sweet. But again one has to be careful not to confuse them with the similar-looking yellow- stainer, Agaricus xanthodermus, which is poisonous.Reuse content