Mushroom Growing Today

By Fred C. Atkins and W. C. Haycraft

This fascinating text provides a detailed guide to the growing of mushrooms, containing a comprehensive treatise on the subject and detailing everything a prospective mushroom-grower could possibly need to know. Informative and accessible, this scarce text is the perfect introduction to the beginner, as well as constituting a great handbook for seasoned practitioners. Chapters included in this text include: What s a Mushroom?, History of Mushroom Growing, The Mushroom industry To-day, Cultivation Overseas, How Mushrooms are Grown, Mushrooms for the Amateur Gardener, Mushrooms for the Country Gentleman, Mushrooms for Nurserymen and Market Gardens, Building a Mushroom Farm, and many more. This scarce book has been elected for modern republication due to its educational value, and is proudly republished here complete with a new introduction to the subject.

• Language: English
• Publisher: Read Books Ltd.
• Release date: Jul 7, 2014
• ISBN: 9781473394292

Book preview

1

The Background to Mushroom Growing

Chapter One

WHAT IS A MUSHROOM?

The mushroom is a form of plant life known as a fungus (plural, fungi). When the seeds of a plant germinate, roots are sent out to explore the growing medium for food, stems and leaves push their way upwards to draw nourishment from the atmosphere, and eventually seeds are formed inside fruit or flowers. In the case of the mushroom, the seed has no sexual origin and is termed a ‘spore’. These spores, which are invisible to the naked eye, send out exploratory root-like threads in all directions within the growing medium and produce fruit (the mushroom itself) without the intermediate stem-and-leaves stage; and new spores develop inside the cap of the mushroom. More rudimentary fungi even dispense with the fruit, producing spores directly from these threads.

The root-like threads (or ‘hyphae’) develop from spores in order to search for food and transmit it to the mushroom. In a multitude of branchings and criss-crossings they frequently fuse together, and are known in the mass as ‘mycelium’. The grower’s term for mushroom mycelium is ‘spawn’.

The mushroom first appears as a tiny white ball. As it grows, a stem is discovered, and later the cap (or ‘pileus’) begins to open up like an umbrella, tearing away the delicate membrane or veil (or ‘velum’) by which its outer edge is attached to the stalk (or ‘stipe’). Inside the cap can now be seen delicate pink gills (or ‘lamellae’) somewhat resembling the spokes of a wheel, radiating from the stalk. These gills darken as the spores growing all over them mature, and when the cap of the mushroom begins to flatten out the spores are released and fall to the ground in their millions. To indicate their microscopic size it has been calculated that the common mushroom produces something like a million spores a minute for several days, and that each spore takes something like forty-five seconds to reach the ground.

The question might be asked: Why, with so many spores floating about, are we not overrun with mushrooms? The answer is that even if spores happen to come to rest on a suitable piece of land and germinate, their mycelium is very sensitive, is readily killed by unsuitable weather, is prey to a host of other fungi and liable to attack from numerous insects. In fact, as is well known, even when growth is firmly established there are seasons when few mushrooms appear in the fields.

Stages in the development of the cultivated mushroom

Sometimes animals eat mushrooms growing in pasture land, and spores are excreted with the dung. It is in these circumstances that the spores, protected from natural enemies, are most likely to germinate. They are so small, of course, that they can also be carried in the intestines of insects, and frequently they are picked up on the hairy legs of flies or in the slime of slugs feeding on the gills of the wild mushroom.

Mr. Angus Watson, Secretary of Mushroom Growers’ and Mushroom Research Associations in England

Growing Mushrooms in Boxes

Courtesy: J. L. Kessler, Esq.

Mushroom Bed in Air-raid Shelter

Courtesy: R. H. T. Gibbens, Esq.

The mushrooms commonly grown are termed the ‘white, cream and brown varieties’. Mycologists seem now agreed that they are specifically distinct from the field mushroom, Agaricus (or Psalliota) campestris, and the horse mushroom, A. (or Ps.) arvensis, but there is considerable divergence of opinion as to whether the genus should be called Agaricus or Psalliota, as to whether they represent two species or two varieties of one species, and as to whether the epithets bisporus or hortensis should be used. The essential difference between wild and cultivated mushrooms is that the former bear their spores in groups of four, the latter usually in twos. If the field mushroom is accepted as the type of the genus Agaricus, then the name Agaricus has priority over Psalliota and should be adopted; if, however, Agaricus is rejected as a source of confusion, then the later name Psalliota can be adopted. If this course is followed and if the white and cream mushrooms are regarded as belonging to the same species as the brown, the correct name seems to be Psalliota bispora, but some authorities prefer the names Agaricus bisporus and A. hortensis. In view of this uncertainty, which may be removed at the next International Botanical Congress, it is fortunate that the ‘Trade’ is content to call them ‘mush’ or ‘rooms’!

The essential difference between wild and cultivated mushrooms is that the former bear their spores in groups of four, the latter usually in twos. Analogies can be misleading, but it is interesting to note here that, as many forms of life become more developed, the number of their offspring tends to decrease.

Not being one of the higher plants, a fungus has no green colouring matter (chlorophyll) and cannot take carbon dioxide from the air. The mushroom, a saprophyte, lives on dead matter. Other fungi are parasites, drawing their nutriment from living matter, though some are facultative and able to live as saprophytes as well. Others still exist only in association with higher plant life, to their mutual advantage—the term is symbiosis.

A great variety of mushrooms grow wild in many parts of the world, though the conservative Englishman fights shy of them, despite the fact that fewer than a dozen species are generally considered poisonous to man. Most of the deaths resulting from mushroom poisoning have probably been due to the belief that a mushroom is safe to eat if it blackens anything silver which is placed with it in the saucepan or frying pan, or if it peels easily. No mushroom (edible or harmful) blackens silver—and some of the best varieties do not peel readily (although the deadly Amanita genus does!) The only safe test is experience; get hold of Dr. John Ramsbottom’s Poisonous Fungi (King Penguin, 1945, 2s.) and its companion, Edible Fungi (King Penguin, 1943)—and eat only those mushrooms you gather yourself. If you ever go ‘mushrooming’ you should take these little books with you.

It is more than likely, as you walk across the meadows in your search for something to enliven your breakfast, that you will come across a ‘fairy ring’ or parts of one. It did not really arise from the Terpsichorean delights of fairy folk! Once upon a time, spores germinated and threw up a clump of mushrooms. The mycelium spread outwards from this point in search of food for the next crop of mushrooms which would quickly exhaust the ground of its food material and cause much of the grass to die. The bareness of the ring is accentuated by the lush grass growing on either side of it—inside the ring because the old mycelium has died and refertilized the land, and just beyond the ring because the continued outward spread of the mycelium incidentally liberates food upon which the grass temporarily thrives.

Each year new circles with a bigger radius are produced. Some ‘fairy rings’ persist for hundreds of years, slowly expanding, but development may be interrupted by obstacles such as streams or roads. In such cases those arcs of the circle which can continue their search for fresh food move steadily outwards from the original centre, independent of the arrested sections.

The terms mushroom and toadstool are often used loosely. One tendency is to describe the umbrella type as a mushroom, and to confine the term toadstool to fungi such as the Puffball and Morel. Another view is that umbrella-type fungi which are edible should be called mushrooms, and poisonous types toadstools.

Chapter Two

HISTORY OF MUSHROOM GROWING

Mushrooms have been esteemed a delicacy for several thousand years, but only within the last three hundred years did the French discover how to cultivate them.

Towards the end of the seventeenth century someone whose name has not been recorded evolved a method of composting horse-manure and planting it with the spawn of wild mushrooms. The earliest known description of how to grow mushrooms in this way was written by a Frenchman, de Tournefort, and published in Paris in 1707. The method described is remarkably similar to that employed to-day. In fact, no radical changes took place until as recently as fifty years ago.

About 1800 the French were starting to grow mushrooms underground, in the quarries round Paris. Horse-manure was stacked in heaps and allowed to heat up naturally. The resulting compost was laid in long ridges and inoculated with spawn dug from meadows or mill-tracks where horses had been trampling. If luck was with them, the spawn turned out to be mushroom spawn, and if they were really fortunate they eventually picked mushrooms.

English growers were quick to take commercial advantage of the extensive natural supplies of wild spawn in this country, and seventy years ago we were exporting spawn to America, Germany, Denmark and even Australia; in a word, we had captured the world market. English ‘brick’ spawn, made from a mixture of horse-manure, cow-manure and loam, was often contaminated by other moulds, full of insects, and of uncertain vigour and strain. That it sold at all is indicative of the state of the mushroom industry at the turn of the century.

The first of a series of blows which soon deprived us of this supremacy was struck by the French. They were not at all happy about our spawn or their own, and in 1894 Costantin and Matruchot succeeded in making pure spawn in a laboratory from mushroom spores. The process was patented but does not appear to have been commercialized, and it was left to Duggar in America to perfect in 1905 a method of making pure spawn from mushroom tissue. As was to be expected, this method was exploited immediately, for the Americans realized that it meant it was now possible for the first time to select and guarantee a particular strain. From that moment mushroom growing began to develop into the highly scientific industry it is to-day.

In the United States in 1918 was marketed what was termed Pure Spore Culture Bottle Spawn. It was produced by collecting spores from a mushroom selected for its size, colour and general appearance, germinating them under aseptic conditions, and injecting them into a bottle of sterilized horse-manure compost. An ordinary milk bottle was used as the culture flask, and the contents were protected from outside contamination during the growing period by means of a plug of cotton-wool. When the compost was permeated with mycelium the bottle was broken and the spawn was ready for planting. Other conditions being right, the grower was now assured of a crop.

It has been suggested that indoor cultivation originated in Sweden, for Lundberg describes mushrooms growing in greenhouses in 1754. It is not known when the first house designed specifically for mushrooms was built, but Callow (writing in 1831) reports that ‘a house of a peculiar construction, after the German practice, was introduced by Oldacre (gardener to the late Sir Joseph Banks), warmed by fire heat and recommended as one well adapted to the growth of mushrooms throughout the year’.

Callow described and sketched such a house in England in which he grew mushrooms on a flat bed on the ground (instead of the customary ‘ridge’ bed) and on shelves one above the other on brackets attached to the walls. This is the earliest record known to the writer in which shelf beds are mentioned.

In 1857 Cuthill discussed what had by then become known as ‘Oldacre mushroom houses’ and were ‘made on purpose, with shelves, having side boards from nine inches to a foot deep, one shelf being placed above another, about two feet apart, with a gangway down the middle’. He went on to say ‘a hot water pipe was the best’ form of heating, and mentioned the popularity of glasshouses which he had been able to keep cool in summer ‘by putting a covering of straw on the top which during hot weather is watered every night’.

It was until as recently as thirty-five years ago, however, that a ‘standard American’ mushroom house was evolved to bring the grower within reach of controlled temperature, humidity and aeration all the year round. With well-insulated walls and false ceiling, not only was the environment to a great extent responsive to the grower’s manipulation of ventilators and the heating system, but the small shelves bracketed to the walls were replaced by half a dozen or more wide shelves on an independent wooden framework. Since then, the tendency in Great Britain has been for smaller houses with three or four shelves in tiers.

The next big advance was due to Pizer. Although in the latter years of the last century the French growers had discovered that ground gypsum (calcium sulphate) prevented greasiness in composts, it was Pizer who at Wye College in 1936 discovered why, and the addition of gypsum to all composts is now universally practised, with immense improvement in spawn growth. Concurrently, much study was in progress concerning diseases and competitive moulds, mainly by Ware, Glasscock and Bewley in this country and by Lambert and Beach in America. Bewley and Lambert also did useful preliminary work on the relationship between soils and yield—growers were beginning to realize that a good soil was almost as important as a good compost. Pests remained a serious menace.

The declaration of war in 1939 meant immediate abandonment of all investigation of mushroom problems in England, and the scale of work in America soon tapered off.

Chapter Three

THE MUSHROOM INDUSTRY TO-DAY

There are mushroom growers in practically every county in Great Britain, but the main centres are Sussex, Yorkshire, Essex, Kent and Herts.

Home production in the ’twenties was supplemented by the importation of about 600 tons of mushrooms annually, mainly from France. It was not until a tariff duty of 8d. per pound was introduced in 1932 that any semblance of stability was achieved by the industry. The Geneva Conference in 1947 altered this tariff to an ad valorem duty of 10 per cent from 1st May to 30th September, and 20 per cent from 1st October to 30th April. A duty which deters an importer only when prices are high is unlikely to be very helpful to a grower when he most needs protection—when prices are low.

But the end of hostilities in 1945 had brought growers in Great Britain face to face with three factors even more alarming.

During the Second World War the Ministry of Agriculture decided that mushrooms not only possessed no value as a food, but they competed with more favoured vegetables for the limited supply of fertilizers (mainly horse-manure, which was becoming alarmingly scarce). In consequence, the mushroom was the one vegetable specifically prohibited as a crop under glass, and elsewhere its growth was discouraged by withdrawal of labour. The mushroom grower had long been an individualist, secretive and conservative, and no representative association existed to present his case in official circles.

In 1945 a number of specialists calling themselves the Midlands Group of Mushroom Growers held a series of meetings to discuss the problems facing the industry, summarizing them as:

(1) The need for a national association;

(2) The necessity for research, particularly related to the provision of some growing medium other than horse-manure.

(3) The shortage of textbooks.

The urgency felt concerning all three matters was demonstrated by the fact that before the year was spent the M.G.A. (the Mushroom Growers’ Association of Great Britain and Northern Ireland) had been formed as a specialist branch of the National Farmers’ Union; the M.R.A. (the Mushroom Research Association Ltd.) was launched on a £4,500 per annum basis to investigate the industry’s cultural problems; and M.G.P. (Midlands Group Publications) was established to commission authoritative leaflets on technical aspects of commercial growing and to publish the M.G.A.’s bulletins.

Within six months of the cease fire