The Board of Health of New York city is very emphatic in its endeavors to rid the city of any accumulation of manure and, a year ago, had under consideration a plan to compel the manure agents, for sanitary reasons, to bale the stable manure. And perhaps this is the reason why it is so easily procured, to wit: A New York gentleman, desirous of engaging in the mushroom-growing business, writes me: "I get my manure from the city in bales. All it costs me is the freight to my place at White Plains." Lucky gentleman! With any amount of the best kind of stable manure gratis, no wonder he wishes to embark in the mushroom ship.
Cow Manure.—This is sometimes used with horse manure in forming the materials for a mushroom bed, and several European writers are emphatic in advocating its use. But I have tried it time and time again, and in various ways, and am satisfied that it has no advantage whatever over plain horse manure, if, indeed, it is as good. It is not used by the market growers in this country.
The best kind of cow manure is said to be the dry chips gathered from the open pastures; these are brought home, chopped up fine and mixed with horse manure. The time and expense incurred in collecting and chopping these "chips" completely overreach any advantages that might be derived from them, no matter how desirable they may be. The next best kind of cow manure is that of stall-fed cattle, to which dry food only, as hay and grain, is fed. This is seldom obtainable except in winter, and is then available for spring beds only. This I have used freely. One-third of it to two-thirds of dry horse manure works up very well, heats moderately, retains its warmth a long time, also its moisture without any tendency to pastiness; the mycelium travels through it beautifully, and it bears fine mushrooms. Still, it is no better than plain horse manure. The poorest kind of cow manure is the fresh manure of cattle fed with green grass, ensilage, and root crops; indeed, such manure can not be used alone; it needs to be freely mixed with some absorbent, as dry loam, German moss, dry horse droppings, and the like, and even then I have utterly failed to perceive its advantages; it is a dirty mass to work, and quite cold.
In the manufacture of spawn, however, cow manure is a requisite ingredient, and here again the manure of dry fed animals is better than that of those fed with green and other soft food. But my chief objection to the use of cow manure in the mushroom beds is that it is a favorite breeding and feeding place for hosts of pernicious bugs and grubs and earth worms,—creatures that we had better repel from, rather than encourage in, our mushroom beds.
German Peat Moss Stable Manure for Mushroom Beds.—Although I have not yet had an opportunity of trying this material for mushroom beds, Mr. Gardner, of Jobstown, has great faith in it; so, too, has that prince of English mushroom growers, Richard Gilbert, of Burghley, who relates his success with it in growing mushrooms in the English garden papers. This peat moss is a comparatively new thing in this country, and is used in place of straw for bedding horses. It is a great absorbent and soaks up much of the urine that, were straw used instead, would be likely to pass off into the drains. To this is ascribed its great virtue in mushroom culture. It should be mixed with loam when used for mushroom beds.
Sawdust Stable Manure for Mushroom Beds.—This is the manure obtained from stables where sawdust has been used for bedding for the horses. It is a good absorbent and retains considerable of the stable wettings. Such manure ferments well, makes up nicely into beds, the mycelium runs well in it, and good mushrooms are produced from it. But if I could get any other fairly good manure I wouldn't use it. I remember seeing it at Mr. Henshaw's place some years ago. He had bought a quantity of fresh stable manure from the Brighton coal yards, where sawdust had been used for bedding for the horses, and this he used for his mushroom beds. I went back again in a few months to see the bed in bearing, but it was not a success. At the same time, some European growers record great success with sawdust stable manure. George Bolas, Hopton, Wirkeworth, England, sent specimens of mushrooms that he grew on sawdust manure beds to the editor of the Garden, who pronounced them "in every way excellent." Mr. Bolas says: "In making up the bed I mixed about one-third of burnt earth with the sawdust, sand, and droppings. The mushrooms were longer in coming up than usual, the bed being in a close shed, without any heat whatever. They have, however, far exceeded my expectations."
Richard Gilbert, of Burghley, also wrote to the Garden, April 25, 1885: "There is nothing new in growing mushrooms in sawdust. I have done it here for years past; that is to say, after it had done service as a bed for horses, and got intermixed with their droppings. I have never been able to detect the least difference in size or quality between mushrooms grown in sawdust and those produced in the ordinary way."
Tree Leaves.—Forest tree leaves are often used for mushroom beds, sometimes alone, instead of manure, but more frequently mixed with horse manure to increase the bulk of the fermenting material. Oak tree leaves are the best; quick-rotting leaves, like those of the chestnut, maple, or linden, are not so good, and those of coniferous trees are of no use whatever. As the leaves must be in a condition to heat readily they should be fresh; such are easily secured before winter sets in, but in spring, after lying out under the winter's snow and rain, their "vitality" is mostly gone. But we can secure a large lot of dry leaves in the fall and pile them where they will keep dry until required for use. As needed we can prepare a part of this pile by wetting the leaves, taking them under cover to a warm south-facing shed, and otherwise assisting fermentation just as if we were preparing for a hotbed. While moistening the leaves with clean water will induce a good fermentation, wetting them with liquid from the horse-stable urine tanks will cause a brisk heat, and for mushrooms produce more genial conditions.
Mushroom beds composed in whole or part of fermenting tree leaves should be much deeper than would be necessary were horse manure alone used; for half leaves and half manure, say fifteen inches deep; for all leaves, say twenty to thirty inches deep.
While mushroom spawn will run freely in leaf beds and we can get good mushrooms from them, my experience has satisfied me that we do not get as fine crops from these beds or any modification of them as from the ordinary stable manure beds. And we can not wonder much at this, considering that the wild mushroom is scarcely ever found in the neighborhood of trees or where leaf mold deposits occur.
Spent Hops.—We can make good use of this in one way. If we are short of good materials for a mushroom bed, we can first make up the beds eight or ten inches deep with fermenting spent hops, and above this lay a four or five inch layer of horse manure, or this and loam mixed. The hops will keep up the warmth, and the manure affords a congenial home for the mushroom spawn. But we should never use spent hops alone, nor so near the surface of the beds that the spawn will have to travel through it.
Spent hops can be had for nothing, and our city brewers even pay a premium to the manure agents to take the hops away.
PREPARATION OF THE MANURE.
Get as good a quality of fresh horse manure as you can, and in sufficient quantity for the amount of bed or beds you wish to make. Next get it into suitable condition for making up into beds. This can be done out of doors or under cover of a shed, but preferably in the shed. Out of doors the manure is under the drying influence of sun and wind, and it is also liable to become over-wetted by rain, but under cover we have full control of its condition. All the manure for beds between July and the end of October is prepared out of doors on a dry piece of ground, but what is used after the first of November, all through the winter, is handled in a shed open to the south. During the autumn months we get along very well with it out of doors; after every turning cover the heap with strawy litter to save it from the drying influences of sun and wind. Remove this covering when next turned, and lay light wooden shutters on top of it as a precaution against rain. In the shed in winter the manure is protected against rain and snow and we can always work it conveniently; when the shed is open to the south—as wagon and wood-sheds often are—we get the benefit of the warm sunshine in the daytime in starting fermentation in the manure, but in the event of dull, cold weather, cover up the pile quite snugly with straw and shutters to start the heat in it. Altogether, a warm, close shed would be better.
It seldom happens that one can get all the manure he wants at one time; it accumulates by degrees. This is the case with the market grower who uses many tons, and hauls it home from the city stables a little at a time; also with the private grower, who uses only a few bushels or half a cord, and has it accumulate for days or weeks from his own stable. As the manure accumulates throw it into a pile, straw and all, but not into such a big pile that it will heat violently; and particularly observe that it shall not "fire-fang" or "burn" in the heap. If it shows any tendency to do this, turn it over loosely, sprinkle it freely with water, spread it out a little, and after a few hours, or when it has cooled off nicely, throw it up into a pile again and tread it firmly to keep it moist and from heating hastily.
When enough manure has accumulated for a bed, prepare it in the following way: Turn it over, shaking it up loosely and mixing it all well together. Throw aside the dry, strawy part, also any white "burnt" manure that may be in it, and all extraneous matter, as sticks, stones, old tins, bones, leather straps, rags, scraps of iron, or such other trash as we usually find in manure heaps, but do not throw out any of the wet straw; indeed, we should aim to retain all the straw that has been well wetted in the stable. If the manure is too dry do not hesitate to sprinkle it freely with water, and it will take a good deal of water to well moisten a heap of dry manure. Then throw it into a compact oblong pile about three or four feet high, and tread it down a little. This is to prevent hasty and violent heating and "burning," for firmly packed manure does not heat up so readily or whiten so quickly as does a pile loosely thrown together. Leave it undisturbed until fermentation has started briskly, which in early fall may be in two or three days, or in winter in six to ten days, then turn it over again, shaking it up thoroughly and loosely and keeping what was outside before inside now, and what was inside before toward the outside now; and if there are any unduly dry parts moisten them as you go along. Trim up the heap into the same shape as you had before, and again tread it down firmly. This compacting of the pile at every turning reduces the number of required turnings. When hot manure is turned and thrown loosely into a pile it regains its great heat so rapidly that it will need turning again within twenty-four hours, in order to save it from burning, and all practical men know that at every turning ammonia is wasted,—the most potent food of the mushroom. We should therefore endeavor to get along with as few turnings as possible; at the same time, never allow any part of the manure to burn, even if we have to turn the heap every day. These turnings should be continued until the manure has lost its tendency to heat violently, and its hot, rank smell is gone,—usually in about three weeks' time. If the manure, or any part of it, is too dry at any turning, the dry part should be sprinkled with water and kept in the middle of the heap. Plain water is what is generally used for moistening the manure, but I sometimes use liquid from the stable tanks, which not only answers the purpose of wetting the dry materials, but it also is a powerful stimulant and welcome addition to the manure. But the greatest vigilance should be observed to guard against overmoistening the manure; far better fail on the side of dryness than on that of wetness.
If the manure is too wet to begin with it should be spread out thinly and loosely and exposed to sun and wind, if practicable, to dry. Drying by exposure in this way is not as enervating as "burning" in a hot pile, and better have recourse to any method of drying the manure than use it wet. If, on account of the weather or lack of convenience for drying, the manure can not be dried enough, add dry loam, dry sand, dry half-rotted leaves, dry peat moss, dry chaff, or dry finely cut hay or straw, and mix together.
The proper condition of the manure, as regards dryness or moistness, can readily be known by handling it. Take a handful of the manure and squeeze it tight; it should be unctuous enough to hold together in a lump, and so dry that you can not squeeze a drop of water out of it.
Some private gardeners in England lay particular stress upon collecting the fresh droppings at the stables every day, and spreading them out upon a shed or barn floor to dry, and in this way keeping them dry and from heating until enough has accumulated for a bed, when the bed is made up entirely of this material, or of part of this and part of loam. But market gardeners, the ones whose bread and butter depend upon the crops they raise, never practice this method, and that patriarch in the business, Richard Gilbert, denounces the practice unstintedly.
Different growers have different ideas of preparing manure for mushroom beds, but the aim of all is to get it into the best possible condition with the least labor and expense, and to guard against depriving it of any more ammonia than can be helped. See Mr. Gardner's method of preparing manure, p. 22.
Loam and Manure Mixed.—Mushroom beds are often formed of loam and manure mixed together, say one-third or one-fourth part of the whole being loam, and the other two-thirds or three-fourths manure; if a larger proportion of loam is used it will render the beds rather cold unless they are made unusually deep. I am not prepared to affirm or deny that this mixed material has any advantages over plain manure; I use it considerably every year and with good results; at the same time, I get as good crops from the plain manure beds. But it has many warm friends who are excellent growers.
In preparing this mixed material I use fresh sod loam well chopped up, and add it to the manure in this way: First select the manure and throw it into a heap to ferment, as before explained; then after the first turning cover the heap with a layer of this loam about three or four inches thick, enough to arrest the steam; at the next turning mix this casing of loam with the manure, and when the heap is squared off add another coating of loam of the same thickness in the same way as before, and so on at each turning until the whole mass is fit for use, and the full complement of loam, say one-fourth the full bulk, has been added. In this way much of the ammonia that otherwise would be evaporated from the manure is arrested and retained.
Some growers, when they first shake out their fresh manure, add the full complement of loam to it at once and mix them together. Others, again, Mr. Denton, of Woodhaven, for instance, prepare the manure in the ordinary way and when ready for use add the quota of loam. I use good sod loam for two reasons, namely, because it is the very best that can be used for the purpose, and, also, after being used in the mushroom beds it is a capital material, and in fine condition for use in potting soft-wooded plants. But the loam commonly used to mix with the manure is ordinary field soil. If the loam is ordinarily moist to begin with, and also the manure, there is very little likelihood of any of the material getting too dry during the preparation. And much less preparation is needed, for the presence of the loam lessens, considerably, the probability of hasty, violent fermentation.
Mr. Withington, of South Amboy, N. J., uses rather a stinted amount of loam in his manure. He writes me: "We made up our beds this year with a proportion of loam in the manure, say one part loam to eight parts manure, but have always used clear manure heretofore, and I think the beds hold out longer than when only manure is used."
MAKING UP THE MUSHROOM BEDS.
The place in the cellar, shed, house, or elsewhere, where we intend to grow the mushrooms, should be in readiness as soon as the manure has been well prepared and is in proper condition for use. The bed or beds should be made up at once. The thickness of the beds depends a good deal upon circumstances, such as the quality of the manure,—whether it is plain horse manure, or manure and loam mixed together,—or whether the beds are to be made in heated or unheated buildings, and on the floor or on shelves. Floor beds are generally nine to fifteen inches deep; about nine inches in the case of manure alone, in warm quarters, and ten to fourteen inches when manure and loam are used. In cool houses the beds are made a few inches deeper than this so as to keep up a steady, mild warmth for a long time. The beds may be made flat, or ridged, or like a rounded bank against the wall; but the flat form is the commonest, and the most convenient where shelves are also used in the same building. Shelf beds are generally nine inches deep; that is, the depth of one board.
In making up the beds, bring in the manure and shake it up loosely and spread it evenly over the bed, beating it down firmly with the back of the fork as you go along, and continue in this way until the desired depth is attained. If it is a floor bed and there is no impediment, as a shelf overhead, tread the manure down firmly and evenly; if the manure is fairly dry and in good condition it will be pretty firm and still springy, but if it is too moist and poorly prepared treading will pack it together like wet rotten dung.
Now pierce a hole in the bed and insert a thermometer. There are "ground" or "bottom-heat" thermometers, as gardeners call them, for this purpose, but any common thermometer will do well enough; and after two or three days examine this thermometer daily to see what is the temperature of the manure in the bed. In roomy or airy structures or where only a small bed has been made it may, in the meantime, be left in this condition. But in a tight cellar I find that the warm moisture arising from the bed condenses in the atmosphere and settles on the top of the manure, making it perfectly wet. In order to counteract this, as soon as the bed is made up I spread some straw or hay over it loosely; the moisture settles on the covering and does not reach through to the manure. Beware of overcovering, as such induces overheating inside the bed. At spawning time remove this covering. The bed will then have become so cool (80 deg. or 90 deg.) that there is very little evaporation from it, consequently little danger of surface-wetting.
The Proper Temperature.—This, in mushroom beds, depends upon the materials of which they are composed, their thickness, how they are built, the situation they are in, and other circumstances. If the manure was good and fresh to begin with, carefully prepared and used as soon as ready, the bed in a few days will warm up to 125 deg., or a little more or less, and this is very good. My best beds have always shown a maximum heat of between 120 deg. and 125 deg.. Had the manure been used a few days too soon the heat would rise higher, perhaps to 135 deg., but this is too warm; in this case I would fork over the surface of the bed a few inches deep to let the heat escape, and after a couple of days compact the bed again. Boring holes all over the surface of the beds with a crowbar is the common way of reducing a too high temperature, and when the heat has subsided sufficiently fill up these holes with finely pulverized dry loam. With loam we can fill them up perfectly, but we can not do this with manure, and if left open they remain as wet sweat holes that are very deleterious to the spreading spawn.
A too high temperature in the beds should be sedulously guarded against, for it wastes the substance of the manure, dries up the interior of the bed, and the mushroom crop must necessarily be starved and short.
Provided that the manure is fresh and good and has been well prepared, if the beds, after being made up, do not indicate more than 100 deg. or 110 deg. no alarm need be felt, for excellent crops will likely be produced by these beds. The thicker the beds are the higher the heat will probably rise in them. Firmly built beds warm up more slowly than do loosely built ones, and they keep their heat longer. If the materials are quite cool when built solidly into beds they are not apt to become very warm afterward. But I always like to make up the beds with moderately warm manure.
It sometimes happens that circumstances may prevent the making up of the beds just as soon as the manure is in prime condition, and even after they are made up the heat does not rise above 75 deg. or 80 deg.. In such a case if the manure is otherwise in good condition and fresh, it is well enough and a good crop may be expected. But if the manure, to begin with, had been a little stale, rotten and inert, I certainly would not hesitate to at once break up the bed, add some fresh horse droppings to it, mix thoroughly, then make it up again. Or a fair heat may be started in such a stale bed by sprinkling it over rather freely with urine from the barnyard, then forking the surface over two or three inches deep and afterward compacting it slightly with the back of the fork. Spread a layer of hay, straw, or strawy stable litter a few inches deep over the bed till the heat rises. If the manure had been moist enough this sprinkling should not be resorted to, but the fresh droppings added instead. When it is applied, however, great care should be taken to prevent overheating; a lessening or entire removal of the strawy covering, and again firmly compacting the surface of the bed will reduce the temperature. Some saltpeter, or nitrate of soda, an ounce to three gallons of liquid, will encourage the spread of the mycelium after the spawn is inserted; a much stronger solution of these salts can now be used than would be safe to apply after the mycelium is running in the bed.
When loam and manure mixed together comprise the materials of which the bed is made, the temperature is not likely to rise so high as when manure alone is used, but this matters not so long as the materials of which the bed is composed are sweet and fresh and not over-moist. But if the materials are cold and stale treat as recommended for a manure bed, always bearing in mind that it is better to have a cold bed that is fairly dry than one that is wet, or, indeed, a warm one that is wet.
Mr. Withington, of South Amboy, has a good word to say for beds of a low temperature. He writes me: "Our beds kept in good bearing two months, though they have borne in a desultory way a month longer. Our best bed this season was one that was kept at an even temperature. The manure never rose above 75 deg. when made up, and decreased to about 60 deg. soon after spawning. Kept the house at 55 deg.."
What is mushroom spawn? Is it a seed or a root? Do you plant it or sow it, or how do you prepare it? are some of the questions asked me now and again. To the general public there seems to be some great mystery surrounding this spawn question; in fact, it appears to be the chief enigma connected with mushroom-growing. Now, the truth is, there is no mystery at all about the matter. What practical mushroom growers call spawn, botanists term mycelium.
The spawn is the true mushroom plant and permeates the ground, manure, or other material in which it may be growing; and what we know as mushrooms is the fruit of the mushroom plant. The spawn is represented by a delicate white mold-like network of whitish threads which traverse the soil or manure. Under favorable circumstances it grows and spreads rapidly, and in due time produces fruit, or mushrooms as we call them. The mushrooms bear myriads of spores which are analogous to seeds, and these spores become diffused in the atmosphere and fall upon the ground. It is reasonable to suppose that they are the origin of the spawn which produces the natural mushrooms in the fields, also the spawn we find in manure heaps. But we never have been able to produce spawn artificially from spores, or in other words, mushrooms have never been grown by man, so far as I can find any authentic record, from "seed." How, then, do we get the spawn? By propagation by division. We take the mushroom plant or spawn, as we call it, and break it up into pieces, and plant these pieces separately in a prepared bed of manure or other material, under conditions favorable for their growth, and we find that these pieces of spawn develop into vigorous plants that bear fruit (mushrooms) in about two months from planting time. When the spawn has borne its full crop of fruit it dies.
Well, then, if we can not produce spawn from spores, and the spawn in the beds that have borne mushrooms has died out, how are we to get the spawn for our future crops? is a question that may suggest itself to the inexperienced. By securing it when it is in its most vigorous condition, which is before it begins to show signs of forming mushrooms, and drying it, and keeping it dry till required for use. But in order to secure the spawn we need to take and keep with it the manure to which it adheres or in which it is spreading. In this way it can be kept in good condition for several years and without its vitality being perceptibly impaired. Keeping it dry merely suspends its growth; as soon as it is again submitted to favorable conditions of moisture and heat its pristine activity returns.
Mushroom spawn can be obtained at any seed store. Our seedsmen always keep it in stock, both the brick (English), and the flake (French) spawn. It is retailed in quantities of one pound or more, and as the article is perfectly dry it can be easily sent by mail in small quantities.
The seedsmen import it from Europe every year along with their seeds. A prominent Boston seedsman writes me: "We get our supply through the London wholesale seedsmen, for the sake of convenience and cheaper ocean freight, etc. Coming with a shipment of other goods and on same bill of lading brings the freight charges down. The low price at which mushroom spawn is sold in quantity can only be maintained with low freight rates, as there is a duty here of 20% on the article."
By direct inquiry of the leading importers in different cities I find that we import about 4500 lbs of French or flake spawn, and 4000 bushels, or 64,000 lbs of English or brick spawn, and that fully a half of this whole importation is handled by the seedsmen of New York city. In New York one firm alone, who make a specialty of supplying market gardeners, has in one year imported 1500 bushels of brick spawn. But the vicinity of New York is the great mushroom-growing center of the country, also the best market for mushrooms in the country. One gardener at Jamaica, L. I., bought 1000 lbs of brick spawn at one time, and a neighbor of his bought 400 lbs; this shows what a large quantity of spawn market gardeners require. And the demand this year is unprecedented; some of our leading importers had sold out their supply before the first of November. And it is not private growers so much as market growers who are the cause of this; the market men find there is money in growing mushrooms and they are going into it.
Spawn comes in the form of dry, hard, solid manure bricks, and also in the form of flakes of half rotted strawy manure. These bricks and flakes are completely permeated with the mushroom mycelium.
The brick spawn is commonly known as English spawn, and what is imported into this country is made in England, mostly about London. The bricks made by the different manufacturers vary a little in size and weight; in some cases ten bricks go to the bushel, in others fourteen, and in others sixteen. This last is the commonest sized brick, and weighs exactly a pound, and measures about eight and one-half inches long, five and one-fourth inches wide, and one and one-fourth inches thick; it is what the London spawn makers call a 9x6x2 inch brick, but it shrinks in drying. In retailing brick spawn in this country it is sold by weight and not by measure.
Mill-track mushroom spawn is advertised by some of our seedsmen, but what they sell under this name is only the ordinary English brick spawn. One of our prominent seed firms who advertise it write me: "Genuine mill-track spawn used to be the best in England, but it has been superseded, although European gardeners still call for English spawn under the name of 'mill-track.'" The real mill-track spawn is the natural spawn that has spread through the thoroughly amalgamated horse droppings in mill-tracks or the cleanings from mill-tracks. It is usually sold in large, irregular, somewhat soft lumps, and is much esteemed by spawn makers for impregnating their bricks, but nowadays, that horses have given place to steam as a motive power in mills, we have no further supply of mill-track spawn for use in spawning our mushroom beds. We do not feel this loss, however, as the spawn now manufactured by our best makers will produce as good a crop of mushrooms as the old mill-track natural spawn used to do.
The flake spawn is what is generally known as French spawn, and is imported into this country from France. But the manufacture of "French" spawn for sale, however, is not strictly confined to France. It is put up in two ways, namely, nicely packed in thin wooden boxes, each containing two or three pounds of spawn, and also loose in bulk when it is sold by weight or measure.
Virgin spawn is what we call natural spawn or wild spawn; that is, the spawn that occurs naturally in the fields, in manure piles, or elsewhere, and without any artificial aid. It is supposed to be produced directly from the mushroom spores, and is not a new growth of surviving parts of old spawn that may have lived over in the ground. It is far more vigorous than "made" spawn, and spawn makers always endeavor to get it to use in spawning the artificial spawn. It is seldom used for spawning mushroom beds because not easy to obtain. Now and again we come upon a lot of it in a manure pile; it looks like a netted mass of white strings traversing the manure. As soon as discovered secure all you can find, bring it indoors to a loft, shed, or room, and spread it out to dry; after drying it thoroughly keep it dry and preserve and use it as you would French spawn, for it is the best kind of flake spawn. In using virgin spawn for spawning beds I have obtained larger and heavier mushrooms than from "made" spawn, and the beds lasted longer in good bearing, but the weight of the whole crop has not been more than from artificial spawn.
How to Keep Spawn.—Spawn should be kept in a dry, airy place, somewhat dark, if convenient, and in a temperature between 35 deg. and 65 deg.. Wherever things will "must," as in a cellar, cupboard against a wall, or in a close, damp building, is a very poor place for keeping spawn. If the spawn is perfectly dry and kept in a dry, airy place, and not in large bulk, and covered, it will bear a high temperature with apparent impunity, but whenever dampness, even of the atmosphere, is coupled with heat, the mycelium begins to grow, and this, in the storeroom, is ruinous to the spawn. Judging from our natural mushroom crops, the spawn for which must be alive in the ground in winter, one concludes that frost should not be injurious to the artificial spawn, still my experience is that hard frost destroys the vitality of both brick and flake spawn. And this is one reason why I get our full supply of spawn in the fall and keep it myself rather than submit it to the mercy of the seed store.
New Versus Old Spawn.—How long spawn may be kept without its vitality becoming impaired is an unsettled question, but there is no doubt, if properly kept, it will remain good for several years. But I can not impress too strongly upon the reader the importance of using fresh spawn. Do not use any old spawn at any price; do not accept it gratis and ruin your prospect of success by using it. It takes three months from the time when the manure is gathered for the beds until the mushrooms are harvested. Can you, therefore, afford to spend this time, and undergo the care and trouble and expense, and court a failure by using old spawn? We have risks enough with new spawn, let alone old spawn. I do not use any more old spawn, but I have used it often and long enough to be convinced of its general worthlessness, unless preserved with the greatest care.
How to Distinguish Good from Poor Spawn.—This is a very difficult matter, notwithstanding what people may say to the contrary. If we could positively tell good from bad spawn, we would never use bad spawn, and, therefore, with ordinary care, have very few failures in mushroom-growing; for good spawn is the root of success in this business. Spawn differs very much in its appearance; sometimes the bricks show very little appearance of the presence of spawn, and still are perfectly good; and again, we may get bricks that are pretty well interlaced and clouded with bluish white mold or fine threads, and this, too, is good. When the bricks are freely pervaded with pronounced white threads this is no sign that the spawn is bad. Bricks dried as hard as a board may be perfectly good; so, too, may be those that are comparatively soft. Mushroom spawn should have a decided smell of mushrooms, and whatever cobweb-like mold may be apparent should be of a fresh bluish white color, and the fine threads clear white. Prominent yellowish threads or veins are a sign that the mycelium had started to grow and been killed. Distinct white mold patches on the surface of the bricks indicate the presence of some other fungous parasite on the mushroom mycelium; the absence of any mushroom smell in the spawn indicates its worthlessness and that the mycelium is dead. One familiar with mushroom spawn can tell with considerable certainty "very living" spawn and "very dead" spawn, but I am far from convinced that any one can decide unhesitatingly in the case of middling or weak spawn.
Mr. S. Henshaw, in Henderson's Handbook of Plants, tells us: "The quality of the spawn may be very easily detected by the mushroom-like smell, ... and I should have no hesitation in picking out good spawn in the dark." Sanguine, surely, but I have tried it and found the test wanting. M. Lachaume says that good spawn shows "an abundance of bluish-white filaments well fitted together, and giving off a strongly marked odor of mushrooms. All those portions which show traces of white or yellow mold or have a floury appearance, should be rejected and destroyed." Mr. Wright says: "A brick may be a mass of moldiness, and yet be quite worthless; and if the mold has a spotted appearance, as if fine white sand had been dredged on and through the mass, it is certain there is no mushroom-growing power there.... If thick threads pass through the mass and there are signs of miniature tubercles on them, then the spawn may be regarded as too far gone.... Clusters of white specks on the spawn denote sterility."
Mr. A. D. Cowan, of New York, who has the reputation of being an excellent judge of mushroom spawn, writes me: "To correctly judge the quality of brick spawn by its appearance requires experience in handling it, and a trained eye which enables one quickly to detect good from bad, fair to middling. As two lots seldom come exactly or nearly alike in appearance, it is hardly possible to give precise rules to follow, excepting the never-failing requisite which the spawn must possess to be good, namely, the moldy appearance on the surface, the more the better, without showing threads. Too many of these to a given space are a sure indication of exhausted vitality, arising generally from the bricks being heaped together when in process of manufacture, before they are sufficiently dried. Healthy bricks are usually of a dusty brown color, and of light weight. Black colored spawn is to be avoided, as a rule, and when the black appearance is very prevalent in a cargo of bricks it is a strong indication that the spawn has not run its course; and as it is not expected to do so after it has reached the hands of the retailer it is economy to cast it aside. Some persons break a brick into several pieces to see how it looks inside. To the experienced eye this is not necessary, or even to lay hands upon it, as the outward moldy appearance is the best of all evidence of its healthy vitality, and this never exists if the bricks have lost their germinating power, excepting, of course, where they have been kept damp, and the spawn has spent its power, which is detected by the white threads appearing in great quantity."
American-made Spawn.—So far as I have been able to find out by diligent inquiry, mushroom spawn is not made for sale in this country. But I am informed that a few growers do save and use their own flake spawn. Some of our principal growers, Van Siclen, Gardner, and Henshaw, for instance, in time past attempted to make their own spawn, but with only partial success, and now they confine themselves to the imported article. But this state of affairs can not long continue. The demand here for fresh mushrooms is so great, the industry of mushroom-growing so important, the price of imported spawn so high, and the quantity of foreign spawn imported annually into this country is so large, that, before long, we hope some one will find it to his advantage to make a specialty of growing mushroom spawn in this country to supply the American market. There is no practical operation in connection with the cultivation of mushrooms so little known or understood by the general grower as the growing (or "making," as it is commonly called) and preserving of mushroom spawn. General cultivators in England and France (outside of the Paris caves) do not make their own spawn; it is a distinct branch of the business, and carried on by specialists who grow mushrooms for sale in winter, and spawn in summer.
The time and attention required to produce a small quantity of first-class spawn are worth more than the cost of the spawn at the seed store. In order to make spawn profitably we must make it in large quantity, and we need not attempt to make it unless we have good materials and conditions for its proper preparation, and will give it every attention possible for its best development.
Because spawn may be made in America is no reason whatever why the American people will buy it. We must produce, at least, as good an article as the best in Europe before we can find countenance in our home market. It is not the shape of the manure brick, its size, fine finish, hardness, softness, or freshness, that counts in this case; it is the fullness and vitality of the mass of mycelium or mushroom plant that is contained within it.
HOW TO MAKE BRICK SPAWN.
As the making of brick spawn for sale is not yet an American industry, but almost entirely confined to England, I think it best to restrict myself to describing how it is made in England. Mr. John F. Barter, of Lancefield street, London, is one of the most successful mushroom growers and spawn makers in Great Britain. He writes me that he confines himself entirely to the mushroom business; he makes his living by it. He grows mushrooms in the winter months and makes spawn in the summer months; he employs men for mushroom bed making from August until March, then, to keep on the same hands during summer, he makes spawn for sale. He grows for and sells in the London market about 21,000 pounds of mushrooms a year, and in summer makes some 10,000 bushels, equal to 160,000 pounds, of brick spawn for sale. The amount of spawn made in a year by this one manufacturer is about three times as much as the total annual importation of mushroom spawn of all kinds into this country. And he is only one maker among several. This fact alone must convince us that mushroom-growing is carried on to a vastly greater extent in European countries than it is here, where we have as good facilities as they have, and an immensely better market.
The manner of making the spawn differs a little with the different manufacturers, and no one can become proficient in it without practical knowledge. I asked Mr. Barter if he thought spawn could be made profitably in this country, paying, as we do, $1.50 a day for laborers, and without any certainty of the same men staying with us permanently. He writes me: "Uncertain labor would be of no use. Of course the wages you pay would not affect it much, as I pay nearly as much as that for my leading men. But to begin with, you must have a man that has had some experience."
About the simplest and best way of making brick spawn that I find described is the following from The Gardeners' Assistant. I may here state that Robert Thompson, the author of this work, was for many years the superintendent of the Royal Horticultural Society's gardens at Chiswick, near London, and, in his day, was regarded as without a peer in practical horticulture, and lived in the midst of the market gardens of London and the principal mushroom-growing district.
"Fresh horse droppings, cow dung, and a little loam mixed and beaten up with as much stable drainings as may be necessary to reduce the whole to the consistence of mortar. It may then be spread on the floor of an open shed, and when somewhat firm it may be cut into cakes of six inches square. These should be placed on edge in a dry, airy place, and must be frequently turned and protected from rain. When half dry make a hole in the broadside of each, large enough to admit of about an inch square of good old spawn being inserted so deep as to be a little below the surface; close it with some moist material the same as used in making the bricks. When the bricks are nearly dry make, on a dry bottom, a layer nine inches thick of horse dung prepared as for a hotbed, and on this pile the bricks rather openly. Cover with litter so that the steam and heat of the layer of dung may circulate among the bricks. The temperature, however, should not rise above 60 deg.; therefore, if it is likely to do so, the covering must be reduced accordingly. The spawn will soon begin to run through the bricks, which should be frequently examined whilst the process of spawning is going on, and when, on breaking, the spawn appears throughout pretty abundantly, like a white mold, the process has gone far enough. If allowed to proceed the spawn would form threads and small tubercles, which is a stage too far advanced for the retention of its vegetative powers. Therefore, when the spawn is observed to pervade the bricks throughout like a white mold, and before it assumes the thread-like form, it should be removed and allowed to dry in order to arrest the further progress of vegetation till required for use. It ought to be kept in a dark and perfectly dry place." I would add, do not keep it where it is apt to become musty or moldy in summer; also keep it in as cool a dry place as possible in summer, and always above 35 deg. in winter.
These other recipes are also given:
"1. Horse droppings one part, cow dung one-fourth, loam one twentieth.
"2. Fresh horse droppings mixed with short litter one part, cow dung one-third, and a small portion of loam.
"3. Equal parts of horse dung, cow dung, and sheep's dung, with the addition of some rotten leaves or old hotbed dung.
"4. Horse dung one part, cow dung two parts, sheep's dung one part.
"5. Horse droppings from the roads one part, cow dung two parts, mixed with a little loam.
"6. Horse dung, cow dung, and loam, in equal parts."
From the above it appears that horse dung and cow dung are the principals in spawn bricks; the loam is added for the purpose of making the other materials hold together; it also absorbs the ammonia, which otherwise would pass off.
J. Burton's Method. From The Kitchen and Market Garden.—Make the spawn in early spring. As cow manure is the principal ingredient used in making the bricks this should be secured before the animals get any green food. Store it on the floor of an open, dry, airy shed, and turn it every few days for a week or two. Then add an equal part of the following: Fresh horse droppings, a little loam, and chopped straw, mixed together. "The whole should then be worked well together and then trodden down, after which it may be allowed to remain for a few days, when it will be required to be turned two or three times a week. If the weather be fine and dry the mass will soon be in a fit condition for molding into bricks, which process can be performed by using a mold in the same way as the brick makers, or, ... the manure may be spread evenly on the floor to a thickness of six inches, and then be firmly trodden and beaten down evenly with the back of the spade. It should then be lined out to the required size of the bricks, and be cut with a sharp spade or turfing iron. In a few days the bricks will be sufficiently dry to handle, when they should be set up edgeways to dry thoroughly, and if exposed to the sun for two or three days they will be ready to receive the spawn. In introducing the spawn two holes large enough to admit a piece of spawn as big as a pigeon's egg should be cut in each brick at equal distances. This should be well beaten in and the surface made even with a little manure. The bricks should then be collected together in a heap and covered with enough short manure to cause a gentle heat, being careful that there is no rank heat or steam to kill the spawn. This must be carefully attended to until the spawn is found to have penetrated through the whole of the bricks, after which they should be stacked away in any convenient dry place."
HOW TO MAKE FRENCH (flake) SPAWN.
I can not do better than to let a practical Frenchman engaged in the business tell this story. In Vol. XIII of the London Garden I find an English translation of M. Lachaume's book, "The Cave Mushroom," and this comment by the editor: "The most complete account of the cave culture of mushrooms which has been published by any cultivator on the spot well acquainted with the subject is that recently published by M. Lachaume."
Lachaume says: "The best spawn to use is what is called 'virgin spawn'; that is to say, which has not yet produced mushrooms. In this country this kind of spawn may be procured of any respectable nurseryman, under the name of 'French spawn.' It differs from English spawn by being in the form of small tufty cakes, instead of in compact blocks. Large mushroom growers, however, always provide themselves with their own spawn by taking it from a bed which is just about to produce its crop, or which has already produced a few small mushrooms.... It is true that by thus 'breeding in and in,' as it were, the mushrooms show a tendency to deteriorate after a time; new spawn must therefore be obtained as soon as any signs of deterioration begin to manifest themselves."
Making French Virgin Spawn.—Condensed from Lachaume's book on mushrooms. Take five or six barrow loads of horse droppings that have lain in a heap for some time, and lost their heat, and mix them with one-fourth of their bulk of short stable litter. Then, in April, open a trench two feet wide, twenty inches deep, and length to suit, at the foot of, but eight inches distant from, a wall facing north. In the bottom of the trench spread a layer three to four inches deep of chopped straw, then an equally thick layer of the prepared manure, all pressed firmly by treading it down. The two layers must now be gently watered, and then another double layer of chopped straw and droppings must be laid, trodden down and watered, and so on until the top of the trench is reached. The bed ought to rise above the level of the ground and be rounded off like the top of a trunk. To prevent excessive dampness from heavy rain cover the mound with a thick layer of stable litter. Three months after filling the trench it should be opened at the side or end. If the pieces of manure are well covered with masses of bluish-white filaments, giving off the odor of mushrooms, the operation has succeeded, and the spawn is fit for use or for drying to preserve for future use. But if the threads are only sparingly scattered through the mass, the trench should be covered up again and left for another month. In saving the spawn the flakes of manure containing the largest amount of spawn filaments should be retained, and those showing a brown appearance rejected. In order to facilitate the drying of the spawn the flakes should be broken into pieces, weighing from one to two pounds; they are then placed in a well ventilated shed, but they must not be piled upon each other. Properly prepared and dried this spawn keeps good for ten years.
A Second Method (by Lachaume). "This is generally adopted by mushroom growers. The formation of the spawn is accelerated by adding pieces of old spawn here and there.... At the beginning of April we must choose a piece of ground situated at the foot of a wall facing north.... The soil ought to be very open and light rather than heavy, so as to avoid dampness. Taking advantage of a fine day, we open a trench sixteen inches wide and at about eight inches from the foot of the wall, and of a length adapted to the quantity of spawn we desire to produce. The earth is thrown out on the side opposite the wall. Manure which has been prepared for a mushroom bed, and has just come into condition is then filled into the trench, leaving, however, a space at one end of it about two feet and six inches in length for the formation of a mushroom bed, which is made by tossing the manure about and shaking it up with the hands, after which it is pressed down with the hands and knees. As soon as the layer of manure reaches six inches in thickness we place along the edge a number of lumps of spawn at about one foot apart. These lumps are placed level with the manure on the edge facing the wall. This portion of the surface of the manure ought to be raised vertically, and should lean against the earthen wall of the trench. The other half of the surface ought to slope gently toward the wall, leaving a space of three or four inches between it and the side of the trench, so that it may be trimmed. The lumps of spawn on this surface should be placed a little backward, so that they may not be broken when the bed is trimmed. The bed is then covered with more manure, until the first lumps of spawn are buried three or four inches deep. A second row of lumps of spawn is then inserted, as described in the directions for making the first row, and the bed is filled up level with the surface of the soil. It is finished by covering it up with a layer of fine, dry soil three or four inches thick. The spawn ought to be very dry, otherwise we shall get a premature crop of mushrooms instead of fresh spawn. At the end of six weeks or a couple of months the new spawn ought to make its appearance, a fact which we may learn by opening the bed. One sign, which will save us the trouble of opening up the beds, is the appearance of young mushrooms on the surface. The layer of earth is first removed, and then the cakes of spawn are treated as described in the directions given for the first method of making spawn."
Third Method (by Lachaume). "By filling in a trench like that described in the first method, by a series of layers of one-third of pigeon or fowl guano, and two-thirds of short manure, containing a large proportion of spent horse droppings, treading it down firmly, watering it if it is too dry, and finishing up with a layer of soil, as described already, we may, at the end of a couple of months, or even a little longer, procure a supply of well-formed cakes of spawn of excellent quality, which may be used in the ordinary manner."
From Mr. Robinson's "Mushroom Culture." "This (French) spawn is obtained by preparing a little bed, as if for mushrooms, in the ordinary way, and spawning it with morsels of virgin spawn, if that is obtainable; and then when the spawn has spread through it, the bed is broken up and used for spawning beds in the caves, or dried and preserved for sale."
From Mr. Wright's book on mushrooms. "French spawn ... is contained in flakes of manure. Neither is it virgin spawn, nor derived immediately from it, ... but is spawn taken from one bed for impregnating another."
Relative Merits of Flake and Brick Spawn.—The flake or French spawn costs about three times as much as the brick or English spawn, and, as it is so much whiter with mycelium than is the brick spawn, many believe that it is more potent and well worth the additional cost. In spawning the beds I use two pounds of flake spawn to plant the same space for which I would use five pounds of brick spawn, and this gives a capital crop, with number of mushrooms a little in favor of the flake spawn, but on account of the larger size of the mushrooms the weight of crop is considerably in favor of the brick spawn. And I find more certainty of a crop in the case of the brick spawn than in the other.
Regarding the respective merits of brick and flake spawn, Mr. Barter, in response to my inquiry, writes me: "I have tried them both, and know brick spawn to be far the best. You see, I do nothing but this mushroom business for a living, so, of course, would use the best kind of spawn for my crop. Generally the French spawn produces one-third less mushrooms than does the brick spawn from the same length of bed, besides, those from the brick spawn are by far the heaviest and fleshiest."
I would here observe that Mr. Barter's remarks apply more to ridge beds out of doors than beds in the cellar or mushroom house. And it is odd, but true, that the flake spawn does not produce as good results in outdoor beds as it does in those under cover.
SPAWNING THE BEDS.
After the mushroom bed is made up it should, within a few days, warm to a temperature of 110 deg. to 120 deg.. Carefully observe this, and never spawn a bed when the heat is rising, or when it is warmer than 100 deg., but always when it is on the decline and under 90 deg.. In this there is perfect safety. Have a ground thermometer and keep it plunged in the bed; by pulling it out and looking at it one can know exactly the temperature of the bed. Have a few straight, smooth stakes, like short walking canes, and stick the end of these into the bed, twelve to twenty feet apart; by pulling them out and feeling them with the hand one can tell pretty closely what the temperature of the bed is.
All practical mushroom growers know that if the temperature of a twelve inch thick bed at seven inches from the surface is 100 deg., that within an inch of the surface of the bed will only be about 95 deg. indoors, and 85 deg. to 90 deg. out of doors. Also, that when the heat of the manure is on the decline it falls quite rapidly, five, often ten degrees, a day, till it reaches about 75 deg., and between that and 65 deg. it may rest for weeks.
Some years ago I gave considerable attention to this matter of spawning beds at different temperatures. Spawn planted as soon as the bed was made (five days after spawning the heat in interior of bed ran up to 123 deg.) yielded no mushrooms, the mycelium being killed. The same was the case in all beds where the spawn had been planted before the heat in the beds had attained its maximum (120 deg. or over). Where the heat in the middle of the bed never reached 115 deg., the spawn put in when the bed was made, and molded over the same day, yielded a small crop of mushrooms. A bed in which the heat was declining was spawned at 110 deg.; this bore a very good crop, and at 100 deg. and under to 65 deg. good crops in every case were secured, with several days' delay in bearing in the case of the lowest temperatures. But notwithstanding these facts, my advice to all beginners in mushroom growing is, wait until the heat of the bed is on the decline and fallen to at least 90 deg., before inserting the spawn.
Writing to me about spawning his beds, Mr. Withington, of New Jersey, says: "I believe a bed spawned at 60 deg. to 70 deg., and kept at 55 deg. after the mushrooms appear, will give better results than one spawned at a higher temperature, say 90 deg.."
Preparing the Spawn.—If brick spawn is used cut up the bricks (standard size) into ten or twelve pieces with a sharp hatchet, and avoid, as much as possible, making many crumbs, as is the case generally when a hammer or mallet is used in breaking the bricks. Extra large pieces of spawn are apt to produce large clumps of mushrooms, but this is not always an advantage, as when many mushrooms grow together in a clump they are apt to be somewhat undersized, and in gathering we can not pluck them all out clean enough so as not to leave a part of the "root" in the ground to poison the balance of the clump, in cases where several or many of them spring from one common base.
Inserting the Spawn.—When brick spawn is used plant the lumps about an inch deep under the surface of the manure, and about ten inches apart each way. If the spawn looks very good, and the lumps are large do not plant them quite so close as when the spawn shows less mycelium in it, and the lumps are small. Never use a dibber in planting spawn; simply make a hole in the manure with the fingers, insert the lump and cover it over at once, and as soon as the bed has been planted firm it well all over. Although the lumps are buried only an inch deep under the manure, we have to make a hole three or four inches deep to push the lump into to get it buried.
French or flake spawn is inserted in much the same way and at about the same distance, only, instead of cutting it up into lumps, we merely break it into flaky pieces about three inches long by an inch thick, and in planting it in the beds, in place of pushing it into the hole, lay in the flake on its flat side and at once cover it.
Many growers plant spawn a good deal deeper than I do, but I have never found any advantage in deep planting. In moderately warm beds, or beds that are likely to retain their heat for a considerable time, I am satisfied that shallow planting is better than deep planting. When we want to mold over our beds soon after spawning them, shallow planting is to be recommended. But if the beds are only 75 deg. to 78 deg., before being spawned; then I think deep planting is better than shallow planting, because the genial temperature gives the mycelium a better start in life than would the cooler manure nearer the surface.
If there is any likelihood of the surface manure getting wet from the condensed moisture of the atmosphere, I would again cover over the beds with some hay or straw, and let it remain on until molding time. And if the bed is a little sluggish,—that is, cool,—this covering will help in keeping it warm. Outside beds should be molded over in three or four days after spawning; inside beds in eight to ten days.
Steeped Spawn.—As brick spawn is so hard and dry I have tried the effect of steeping it in tepid water before planting; some pieces were merely dipped in the water, and others allowed to soak in the pails one-half, one, five, and ten hours. The effect was prejudicial in every instance and ruinous in the case of the long-soaked pieces.
Flake Spawn.—"This is produced by breaking up the brick spawn into pieces about two inches square and mixing them in a heap of manure that is fermenting gently. After lying in this heap about three weeks it will be found one mass of spawn, and just in the right condition for running vigorously all through the bed in a very short time.... When flake spawn is used the appearance of the crop is from two to three weeks earlier than when brick spawn is used."—Mr. Henshaw, in first edition of "Henderson's Handbook of Plants." I have tried this method and given it careful attention, but the results were inferior to those obtained where plain, common brick spawn had been used at once.
In all my practice I have found that any disturbance of the spawn when in active growth which would cause a breaking, exposing, or arresting of the threads of the mycelium has always had a weakening influence upon it. I have transplanted pieces of working spawn from one bed to another, as the French growers do, but am satisfied that I get better crops and larger mushrooms from beds spawned with dry spawn than from beds planted with working spawn from any other beds.
LOAM FOR THE BEDS.
In growing mushrooms we need loam for casing the beds after they are spawned, topdressing the bearing beds when they first show signs of exhaustion, filling up the cavities in the surface of the beds caused by the removal of the mushroom stumps, and for mixing with manure to form the beds. The selection of soil depends a good deal on what kind of soil we have at hand, or can readily obtain.
The best kind of loam for every purpose in connection with mushroom-growing is rich, fresh, mellow soil, such as florists eagerly seek for potting and other greenhouse purposes. In early fall I get together a pile of fresh sod loam, that is, the top spit from a pasture field, but do not add any manure to it. Of course, while this contains a good deal of grassy sod there is much fine soil among it, and this is what I use for mushrooms. Before using it I break up the sods with a spade or fork, throw aside the very toughest parts of them, and use the finer earthy portion, but always in its rough state, and never sifted. The green, soddy parts that are not too rough are allowed to remain in the soil, for they do no harm whatever, either in arresting the mycelium or checking the mushrooms, and there is no danger that the grass would grow up and smother the mushrooms.
Common loam from an open, well-drained fallow field is good, and, if the soil is naturally rich, excellent for any purpose. But do not take it from the wet parts of the fields. Reject all stones, rough clods, tussocks, and the like. Such loam may be used at once.
Ordinary garden soil is used more frequently than any other sort, and altogether with highly satisfactory results. The greatest objection I have to it is the amount of insects it is apt to contain on account of its often repeated heavy manurings.
Roadside dirt, whether loamy or gritty, may also be used with good results. If free from weeds, sticks, stones and rough drift, it may be used at once, but it is much better to stack it in a pile to rot for a few months before using.
Sandy soil, such as occurs in the water-shed drifts along the roads and where it has been washed into the fields, is much inferior to stiffer and more fibrous earth.
I have used the rich dark colored soil from slopes and dry hollows in woods, and, odd though it may appear, as mushrooms do not naturally grow in woods, with success. But it is not as good as loam from the open field.
Peat soil or swamp muck that has been composted for two or three years has failed to give me good returns. The mushrooms will come up through it all right, but they do not take kindly to it.
Heavy, clayey loam is, in one way, excellent, in another, not so good. So long as we can keep it equably moist without making it muddy it is all right, but if we let it get a little too dry it cracks, and in this way breaks the threads of the spawn and ruins the mushrooms that were fed through them.
Loam Containing Old Manure.—Loam in which there is a good deal of old, undecomposed manure, such as the rich soil of our vegetable gardens, is unqualifiedly condemned by some writers because of the quantity of spurious and noxious fungi it is supposed to produce when used in mushroom beds. But I can not join in this denunciation because my experience does not justify it. This earth is the only kind used by many market gardeners, as they have no other, and certainly without apparent injurious effect. When I was connected with the London market gardens, some twenty years ago, Steele, Bagley, Broadbent, and the other large mushroom growers in the Fulham Fields cased all of their beds with the common garden soil—perhaps the most manure-filled soil on the face of the earth—and spurious fungi never troubled them. Indeed, I can not understand why it should produce baneful crops of toadstools when used in mushroom beds, and no toadstools when used for other horticultural purposes, as on our carnation benches in greenhouses, in our lettuce or cucumber beds, or in the case of potted plants. True, spurious fungi may appear in the earth on our greenhouse benches or frame beds or mushroom beds at any time and in more or less quantity, but I am convinced that the rich earth of the vegetable garden has no more to do with producing toadstools than has any other good soil, and old manure has far less to do with it than has fresh manure.
All practical gardeners know how apt hotbeds, in spring when their heat is on the decline, are to produce a number of toadstools; and, also, that when the bed is "spent," that is, when the heat is altogether gone, the tendency to bear toadstools has gone too. This peculiarity is more apparent in spring than in fall. All mushroom growers know that spurious fungi, when they appear at all, are most numerous three to two weeks before it is time for the mushrooms to come in sight. The same growth appears in the manure piles out in the yard; a few weeks after the strong heat of the manure has gone lots of toadstools may be observed on and about the heaps, but on the piles of well-rotted cold manure we seldom find toadstools at all.
The fresh, clean stable manure used in mushroom-growing is not apt to be charged with the spores of pernicious toadstools; their presence is always most marked in the case of mixed manures.
And there is a current idea that mushrooms will not thrive in beds in which old manure abounds, either in the loam or fermenting material; that it kills the mycelium. This, too, I must refute. I have seen heavy crops of spontaneous mushrooms come up in violet and carnation beds in winter, and where the soil consisted of at least one-fourth of rotted manure well mixed with the earth. In cucumber and lettuce beds the same thing has taken place. And in similar beds that have been planted artificially with spawn, good crops of mushrooms have also been raised, and the mycelium, instead of evading the lumps of old manure in the soil often forms a white web right through them.
EARTHING OVER THE BEDS.
This is an important operation in mushroom-growing, and the one for which loam is indispensable. It consists in covering the manure beds, after they have been spawned, with a coating, or casing as it is more commonly called, of loam. The spawn spreads in the manure and rises up into the casing, where most of the young mushrooms develop, and all find a firm foothold. The loam also contributes to their sustenance. And it protects the manure, hence the spawn, from sudden fluctuations of temperature, and preserves it from undue wetting or drying.
The best soil to use for this purpose is rich, fibrous, mellow loam, such as is described, page 100.
If the manure is fresh and in good condition and the beds are in a snug cellar or closed mushroom house, I would not case them until the second week after spawning, say about the eighth or tenth day; but were these same beds in an open, airy shed or other building I would case them over some days earlier, say the fourth or fifth day. A fear is often expressed that when beds are cased within three or four days after being spawned the close exclusion of the manure from the air is apt to raise the heat of the manure in the bed, and thereby destroy the spawn; but I have never known of any truth in this theory, and with well-prepared manure I am satisfied no brisk reheating takes place, at least the thermometer does not indicate it. The great danger of early casing is in killing the spawn by burying it too deep in damp material and before it has begun to run through the manure.
I have conducted several experiments in order to satisfy myself regarding when is the proper time to case the beds, and have found no difference in results between beds that were cased over as soon as they were spawned and others that were not cased over until the fourth, seventh, tenth, or fourteenth day after spawning. The good or bad results in the time of casing depend on the condition of the manure in the beds, the depth at which the spawn has been inserted, the openness or closeness of the place in which the beds are situated, and other cultural conditions. But to delay casing as late as the fifteenth or sixteenth day after spawning is injurious to the crop, because in applying the covering of soil we are sure to break many of the mycelium threads that have by this time so freely permeated the surface of the manure. After the fourth week little white knots may be observed here and there on the spawn threads; these are forming mushrooms, and to delay casing the bed until this time would smother these little pinheads, and greatly mar our prospects of a good crop.
Peter Henderson, in his invaluable work, "Gardening for Profit," has given rise to a deep seated prejudice against molding over mushroom beds as soon as they are spawned by telling us that in his first attempt at mushroom-growing he had labored for two years without being able to produce a single mushroom, and all because he molded over his beds with a two-inch casing of loam just as soon as he had spawned them. Then he changed his tactics, and did not mold over the beds until the tenth or twelfth day after spawning, and was rewarded with good crops of mushrooms. Now, notwithstanding Mr. Henderson's experience, it is a fact that many excellent growers spawn and mold their beds the same day, and with success. But Mr. H. has done much good in displaying a rock against which many might be wrecked, so much depends upon other cultural conditions. The old practice of inserting the spawn three or more inches deep into the manure bed and then molding it at once with two inches deep of loam was enough to destroy the most potent spawn; nowadays we barely cover the spawn with the manure, and this is how molding over at once is so successful.
All the preparation necessary is to have the loam in medium dry, mellow condition, well broken up with the spade or digging fork, and freed from sticks, stones, big roots, clods, chunks of old manure, and the like.
Sifting the soil for casing the beds is labor lost. Sifted soil has no advantage over unsifted earth, except when it is to be used for topdressing the bearing beds or filling up the holes in their surface.
The condition of the soil should be mellow but inclined to moist. If wet it can only be used clumsily and spread with difficulty; if dry it can be spread easily but not made firm, and on ridge beds can not be put on evenly. But when moderately moist it can be spread easily and evenly on flat or rounded surfaces, and made firm and smooth.
How deep the mold shall be put upon the bed is also an unsettled question. Some growers recommend three-fourths of an inch, others one, one and one-half, two, or two and one-half inches, and some of our best growers of fifty or seventy-five years ago were emphatic in asserting three inches as the proper depth, but among recent writers I do not find any who go beyond two and one-half inches. My own experience is in favor of a heavy covering, say one and one-half to two inches. In the case of a thin covering the mushrooms come up all right but their texture is not as solid as it is in the case of a heavy covering, nor do the beds continue as long in bearing; besides, "fogging off" is much more prevalent under thinly covered than under heavily covered beds; also, when the coating of loam is heavy a great many more of the "pinheads" develop into full sized mushrooms than in the case of thinly molded beds.
Opinions differ as to firming the soil. I am in favor of packing the soil quite firm, and have never seen good mushrooms that could not come through a well firmed casing of loam, and I never knew of an instance where firm casing stopped or checked the spreading of the mycelium or the development of the mushrooms. In the case of flat beds,—for instance, those made on shelves and floors,—a slightly compacted coating (and this is all Mr. J. G. Gardner uses) may be all right, but in the case of alongside-of-walls, ridge, and other rounded beds I much prefer and always use solidly compacted casings.
Mr. Henshaw has for several years used green sods about two inches thick, put all over the bed, grass side down, and beaten firmly. The advantage of using sods instead of soil, he thinks, is that the young clusters of mushrooms never damp or "fogg off" as they are apt to do when soil is used.
I have given this green sods method repeated and careful trials, and am satisfied that it has no advantages, in any way, over common fibrous loam; indeed, it is not as good. No matter how firmly a sod, having its green side down, may be beaten on to a bed of manure, there is barely any union between the two; the sod merely rests upon the dung, but so closely that the mycelium enters it freely. A slight movement or displacement of the sod after the spawn enters it will break the threads of mycelium between the manure and the sod, and this will destroy the immature mushrooms forming in the sod. This gave me a good deal of trouble. Stepping on the sod would disturb it. A clump of strong mushrooms formed under it sometimes displaces it in forcing their way to the surface.
Sods are only fit for use on flat beds where they can lie solid; on rounded or ridge beds they are too liable to be disturbed. And the trouble and expense of procuring sods are too great to warrant their use, even if they had any advantages.
TOPDRESSING WITH LOAM.
In beds that are in full bearing or a little past their best we often find multitudes of very small or what we call "pinhead" mushrooms, that seem to be sitting right on the top of the loam, or clumps that have been raised a little above the surface by growing in bunches, or what we term "rocks"; now a topdressing of finely sifted fresh loam, about one-fourth to one-half inch thick, spread all over the bed, will help these mushrooms materially without doing any of them harm. But while this topdressing assists all mushrooms that are visible above ground, no matter how small they may be when the dressing is applied, I am not convinced that it induces greater fertility in the spawn, or, in other words, induces the spawn to spread further and produce more mushrooms than it would were no topdressing applied. I know that this is contrary to the opinions and writings of many, at the same time it is according to my own observation.
Go over the bed very carefully and pick out every soft or "fogged-off" mushroom, no matter how small it may be, and root out every bit of old mushroom stem or tough spongy material formed by it, and in this way get the bed thoroughly cleaned. Then fill up all the holes caused by pulling the mushrooms or rooting out the old stumps, and when the whole surface is level apply the topdressing evenly all over the face of the bed, avoiding, as much as possible, burying the well advanced mushrooms. While it would be very well to pack the dressing smoothly over the bed, it is impracticable; we may press it gently with the back of the hand on the bare spots between the mushrooms, but we should not even do this over the mushrooms, no matter how tiny they may be, else many of the "pinheads" will be injured and cause "fogging off."
But we can firm the dressing to the bed by watering it, which may be done over the whole surface of the bed, and without sparing the mushrooms, large or small. Use clear water and apply it gently through a water-pot rose. I always do this, and have never known it to injure the young mushrooms.
In the case of mushroom beds in which black spot has appeared in the crop, I have found that a topdressing of fine, fresh earth applied evenly all over the bed acts, to a certain extent, as a preventive of further attack, but of course has no effect upon any of the already affected mushrooms, large or small.
THE PROPER TEMPERATURE.
The best temperature at which to keep the mushroom house or cellar is 55 deg. to 57 deg.. But much depends upon the method of growing the esculent; the construction of the house or cellar, and other circumstances. Mushrooms can be successfully grown in buildings in which the temperature may be as low as 20 deg. or as high as 65 deg.. By covering the beds well with hay or other protecting material they can be kept warm, even in sharp frosty weather, as the London market gardeners do with their outdoor beds in winter; but when the temperature in the structure in which the mushrooms are grown averages as high as 70 deg. we can not hope for success; indeed, 65 deg. is too high.
A high temperature in a close house or cellar is injurious; it hurries in the crop and forces up the mushrooms weak and thin-fleshed and with ungainly, long stems; it soon exhausts the bed. The time when its evil effects are least visible is early in the fall and late in spring when the outside temperature is high, and when the beds are in somewhat airy rather than close quarters. In the Dosoris cellars there is a steady difference of about 5 deg. in the temperature between the end next the boiler, which is kept at 60 deg. precisely, and that of the farther end, which registers 55 deg. steadily. There is very little difference in the weight of crop produced on the beds at either end of these cellars, but what little there is is in favor of the cooler end. At 60 deg. the crop begins to come in in six to seven weeks after spawning, lasts for three to four weeks in heavy bearing and a week or more longer in light bearing, and then it gradually dwindles.
In a temperature of 55 deg. it may be seven weeks after spawning before the mushrooms appear. In a temperature of 50 deg. they may take a few days longer in appearing, but, as a rule, they are firm, heavy, short-stemmed, and perhaps a little furry on top and clammy to the touch, and the beds last in good bearing for two months; indeed, often a whole winter long. But I have failed to find that the whole crop from a bed in a 45 deg. to 50 deg. temperature was any greater than that of a like bed in a 55 deg. to 57 deg. temperature; it is merely a case of getting in six weeks from the warmer house what it takes ten weeks to get from the cooler one.
In a temperature of 50 deg. it is not necessary to cover the beds to increase their warmth, nor is it needful even in one of 45 deg., if there is a fair warmth in the body of the bed to keep the spawn working; but if the warmth of the interior of the bed falls under 57 deg., and the atmospheric temperature under 45 deg., the bed should be kept warm by covering with hay, straw, matting, or other material, or better still by boxing it over and laying this covering on the outside of the boxing. When cold thicken the covering, when warm lessen it.
WATERING MUSHROOM BEDS.
If the beds get dry they should be watered, for mushrooms will not grow well in dry beds or in a dry atmosphere. Watering is an operation requiring much care. In properly-made beds the manure should remain moist enough from first to last, and whatever dryness is evident should be in the loam casing of the beds and the atmosphere. In all artificially heated mushroom houses the beds and atmosphere are apt to get too dry at one time or another; in underground houses or cellars this is less apparent than in above-ground structures; in shaded north-facing houses dryness is less troublesome than in houses more openly placed.
Endeavor by all fair means to lessen the necessity for watering the beds, but when water is needed never hesitate to give it freely. Mulching the beds and maintaining a moist atmosphere are the best preventives. After the beds are spawned and molded it is a good plan to cover them with a light coating of strawy litter or hay to prevent drying, but this mulching should be removed when it is near time for the young mushrooms to appear. A light sprinkling of water over this mulching every few days, but never enough to reach the soil, assists in preserving enough moisture in the bed under the mulch and also in the atmosphere of the house.
Clean, soft water at a temperature of 80 deg. or 90 deg.; a little warmer or a little colder will not hurt, but do not use water higher than 110 deg., as it might injure the little pinheads, nor lower than the average temperature of the house, as it would chill the bed, and this should always be avoided.
Use a small or medium-sized watering pot with a long spout and a fine rose sprinkler. Apply the water in a gentle shower over the bed, mushrooms and all, but never use enough to allow it to settle in pools or run off in little streams. Clean water sprinkled over the mushrooms does not appear to hurt them, but they should never be touched with manure water, as it stains them. Just as soon as the surface of the bed shows signs of dryness give it water, the quantity depending upon the condition of the bed. Never let a bed get very dry before watering it. To thoroughly moisten a very dry bed requires a heavy watering; so much, indeed, that the sudden change might injuriously affect the young mushrooms and spawn. Give enough water at a time to moderately moisten the soil, not to soak it, but never sufficient to pass through the soil into the manure. Clean water only should be used until the beds come into bearing, but after that time manure water may be employed with advantage; however, this is not at all imperative; indeed, excellent crops can be and are continually being produced without the aid of manure water at all.
In the case of beds in full bearing, manure water is beneficial to the crop. Apply it from a small watering pot with a long narrow spout but no rose, and pour the liquid on gently over the surface of the bed, running it freely between the clumps but never touching any of the mushrooms. For this reason a rose should not be used.
I have always used manure water for mushrooms more or less, but during the past two seasons—'87-'88 and '88-'89—I have experimented with it continuously and very carefully, using it in some form or other on part of every bed, and am satisfied that manure water made from fresh horse droppings is the best, and the dark colored liquid, the drainings from manure piles, is the poorest; in fact, this latter is not as good as plain water, for it seems to have a deadening rather than quickening effect upon the beds. Cow manure and sheep manure make a good liquid manure, but still I prefer the horse manure, and although having given hen and pigeon manure and guano fair tests I am not satisfied that they have benefited the crop, and there is always a risk in their use. Liquid manure made from the contents of the barnyard tank has not done much good, but fresh urine from the horse and cow stables diluted twelve to fifteen times its bulk has given favorable results.
Mushrooms not only bear with impunity but appear to enjoy a stronger liquid manure more than do any other cultivated plants, and I am satisfied that the weak liquids usually recommended for pot and garden plants would be barely more efficacious than plain water for mushrooms.
The manure water that has given me most satisfaction is prepared as follows: Dump two bushels of fresh horse droppings into a forty-five gallon barrel and fill up with water; stir it up well and let it settle over night. Drain off the liquid the next day and add a pound of saltpeter to it. For use, to a pailful of this liquid add a pailful of warm water. Water of about 80 deg. to 90 deg. is best for mushroom beds. Saltpeter is an excellent fertilizer for mushrooms. I use it in two ways, namely: First, powdered and mixed in the soil for casing the beds, at the rate of two ounces of saltpeter to the bushel of earth. Second, dissolved in water at the rate of two ounces of saltpeter to eight gallons of water, and sprinkled over the beds.
Common salt I use as an insecticide and also as a fertilizer, and am satisfied that it proves beneficial in both ways. Sometimes I sprinkle it broadcast on the surface of the beds, always on the bare places, never touching the mushrooms, and leave it there for a day or two, then with a fine, gentle sprinkling of water wash it into the soil. This is to help destroy the anguillulae. As a fertilizer only dissolve four ounces of salt in ten gallons of water, and with this sprinkle the beds.
A too dry atmosphere can be remedied by sprinkling the floors, walls, or litter coverings on the beds with water, not heavily or copiously, but gently and only enough to wet the surfaces; better moisten in this way frequently than drench the place at any one time. But I very much dislike sprinkling the beds in order to moisten the atmosphere. An experienced man can tell in a moment whether or not the atmosphere of the mushroom house is too dry. The air in the mushroom house should always feel moist, at the same time not raw or chilly, and the floor and wall surfaces should present a slow tendency to dry up, and the earth on the beds should retain its dark, moist appearance. The least tendency to dryness should at once be relieved by damping the wall and floor surfaces.
In houses heated by smoke flues, or still more by ordinary stoves and sheet iron pipes, it may be necessary to dampen the floors and walls once or several times a day to maintain a sufficiently moist atmosphere, but where hot water pipes are used and the houses are tight enough to require but little artificial heat, such frequent sprinkling will not be necessary. In the case of beds in unheated structures the ordinary atmosphere is generally moist enough.
Manure Steam for Moistening the Atmosphere.—The late James Barnes, of England, a grand old gardener, writing in the London Garden, Vol. III, page 486, describes his method of growing mushrooms sixty years ago, and says: "In winter a nice moist heat was maintained by placing hot stable manure inside, and often turning it over." Mr. John G. Gardner, of Jobstown, N. J., is one of Mr. Barnes's old pupils and a most successful mushroom grower, and he now practices this same method of moistening the atmosphere by hot manure steam. See page 21.